CZ20002408A3 - Actively adjustable multifocal lenses - Google Patents

Abstract

The active multifocal optical lens has a first optical element (12) that provides a first optical power that corrects, for example, myopia, and a second optical element (14) that provides a second optical power, wherein the second optical element (14) is a volume holographic optical element that has been programmed to focus incoming light. The biocompatible holographic element is producible from a crosslinkable or polymerizable prepolymer, wherein the prepolymer crosslinks or polymerizes to form a non-fluid biocompatible optical element during up to 5 minutes of irradiation with an ultraviolet light source, wherein the prepolymer is a functionalized copolymer of vinyl lactam and CO . a second vinyl monomer.

Description

Field of technology,

_The invention relates to multifocal lenses containing _a holographic element and providing at least two optical powers.

Current state of the art

Currently, bifocal ophthalmic lenses of various designs are available, which are placed in or on the eye for the purpose of correcting vision defects, such as contact lenses or intraocular lenses. One of the common ophthalmic lens designs is the type

J'concentric simultaneous vision. Concentric simultaneous bifocal lens with two optical zones which are concentric to each other. These concentric alternating optical zones have different radii of curvature in order to achieve two different optical powers - for near-images and for far-images and thus 'focusing near and far images in a /-common focal area. ' Even though concentric bifocal lenses are ^{available ,} they have not been widely used in practice ^. The reason is that the images projected onto the retina ^by a concentric bifocal ^lens are composed of both near ^and far images ^, and the overlapping of these images results in neither the near nor the far images being completely clear. For example, if a distant object is observed through a concentric bifocal lens, both near and far images are present. near objects that obscure or blur the image of a distant object. In addition, since the light entering the concentric bifocal lens is divided into two optical zones, bifocal vision is detrimental to the contrast and intensity of the focused object, which is

-especially noticeable in poor lighting conditions.

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Another concept of a conventional bifocal ophthalmic lens is the concept of the diffractive simultaneous vision type. These lenses have a diffractive optical element and a refractive optical element and use both optical elements to simultaneously project a distant and a near image onto the retina. Like a concentric simultaneous bifocal lens, a diffractive simultaneous bifocal lens splits the light entering the eye into a near and a far image and projects these images simultaneously onto the retina. As a result, neither the near nor the far image is completely clear.

. distant Image> which again results in a problem related to insufficient contrast and brightness of the observed objects, which again is undesirable, especially in . '' poor lighting conditions. . _ _ _L __ ¹

Yet another concept of conventional bifocal ophthalmic lenses is the translational type concept. A translational bifocal constant lens generally follows the concept of conventional bifocal spectacle lenses. A translational lens has two differently located vision sections that have different optical powers. The position of the bifocal lens on the eye must be shifted from one position to another when the wearer wishes to see objects that are located at a distance different from the distance at which the currently focused objects are located. The main problem inherent in conventional translational bifocal lenses is the difficulty faced by the wearer when attempting to change the position of the lens on the eye. The lens must move a relatively large distance on the eye when changing from vision through one section to vision through the other section, and the shift from one section to the other must be completely completed before clear vision can be achieved.

. Recently, an actively controllable concept has been proposed to achieve bifocal function of the lens. An example of such a concept is a simultaneous vision type bifocal lens having thermochromic coatings applied to the . sections. This bifocal lens is . designed to activate the thermochromic coating on the optical zone of the lens for distance vision in the event that the wearer looks down to focus on a certain near object. The thus activated ''thermochromic coating on the distance vision section blocks light passing through the distance vision section, thereby . preventing the image of the observed near object from being 'fogged' or 'fogged' by the image of distant objects. However, this concept is not very practical since .commonly available materials for thermochromic coatings do not activate. "and do not deactivate quickly enough for the practical application of the concept." Another concept uses a lens that changes its focal length using a switchable _battery or photocell. This concept is also not very practical because the electrical circuit and power source must be small enough to be placed in the eye lens, while at the same time being reliable and durable. _ _________ , ___________

In view of the above, it is clear that there is still a demand for ophthalmic lenses that would reliably ensure the multifocal function of the multifocal lens technology. In addition, and while not having the shortcomings of the prior art, there is still a demand for optical materials that would be easily processable in order to obtain a holographic optical element.

The essence of the invention

-In accordance with the invention, a multifocal lens is provided comprising a volume holographic element having an optical power. The lens has more than one optical power, one of which optical powers can be actively and selectively controlled by the wearer of the lens to enable the wearer to see clear and unpaired images. The lens is suitable for a variety of optical lenses, including contact lenses, spectacle lenses and intraocular lenses.

In one embodiment, the invention provides a multifocal optical lens having a first optical element and a volume holographic optical element, the first optical element providing a first optical power at a first focus and the holographic optical element or the holographic optical element in combination with the first optical element providing a second optical power at a second focus. In another embodiment _, the invention provides a multifocal lens having a volume holographic optical element

_.__element,__wherein this__holographic optical element has a programmed activation angle, and -this optical element provides a first optical .power, for example a corrective optical power, ' for light entering this optical element at an angle that is. outside the range of the . activating angle, and a second optical power for light entering this optical element at an angle falling within the range of the activating angle.

The invention also provides a method for correcting vision defects. The method includes the steps of placing a multifocal lens on the eye and moving the multifocal lens on the eye so that the focal point is located at the focal point (fovea) of the eye. The multifocal lens may be characterized by having a first optical element and a volume holographic optical element, the first optical element providing a first optical power at the first focal point and the holographic optical element or the holographic ^optical element in combination with the first optical element providing a second optical power at the second focal point. In another embodiment, In one embodiment of the invention, said multifocal lens may be characterized by having a holographic optical element having a programmed actuating angle, said optical element providing a first optical power for light entering said optical element at an angle outside the actuating angle range and a second optical power for light entering said optical element at an angle within the actuating angle range;

The multifocal lens of the invention is a highly effective corrective lens that does not suffer from the disadvantages of simultaneous vision lenses and conventional translation lenses. The invention provides a biocompatible holographic element produced from a crosslinkable or polymerizable polymer. ... This prepolymer is selected from crosslinkable or polymerizable optical materials that are capable of forming a non-liquid or solid biocompatible optical element within up to 5 minutes of irradiation with an ultraviolet light source. The crosslinking or polymerization time is measured by placing the prepolymer between a lower and upper quartz slide and irradiating the prepolymer with an ultraviolet light source, which is a 200 W medium pressure mercury lamp located 18 cm above said upper quartz slide. Preferably, the biocompatible holographic element is a transmission volume holographic element. The invention also provides a hydrogel holographic element that is made from said prepolymer. In addition, the invention provides a method of making a holographic element from a liquid prepolymer or monomer composition.

This holographic element can be used as a medical device, for example as an optical lens or an ophthalmic lens. Such an optical lens having said holographic element is relatively easy to manufacture and very suitable for correcting various ametropic conditions.

Overview of images in drawings

On the attached drawings:

Fig. 1 shows an active ophthalmic lens according to the invention;

Fig. 2 shows the diffraction function of a holographic optical element for an active lens according to the invention;

Fig. 3 shows an active ophthalmic lens according to the invention;

• . . Fig. 4 shows the transmission function of the holographic optical element; - , . Fig. 5 - - shows the diffraction function of the holographic optical element when this element is activated;

Fig. 6 shows an exemplary method of manufacturing a holographic optical element;

Fig. 7 shows the optical power of a holographic optical element; Fig. 8 to Fig. 8B show an optical element according to the invention and a combination of holographic and optical elements; Fig. 9 shows a spectacle lens composite according to the invention.

The invention provides active multifocal ophthalmic lenses. The invention further provides active multifocal lenses for spectacles. Furthermore, the term optical lens will refer to both ophthalmic and spectacle lenses unless expressly stated otherwise. Active optical lenses according to the invention provide more than one optical power. More specifically, these lenses provide at least one optical power and at least one additional optical power that can be activated. Unlike previously known bifocal lenses, active multifocal lenses according to the invention can be actively and selectively controlled to achieve only one optical power at a given time, without or substantially without optical interference with other optical powers of the lens.

The optical lens comprises a holographic optical element (HOE), and suitable holographic optical elements for active optical lenses are transmission-volume holographic optical elements. The volume holographic optical element comprises interference scattering structures that are programmed or recorded as a periodic change in the refractive index of the optical material. The periodic

The change in the -^i-n-dex-u—l-omu—will create planes of maximum index. - i.e., a volume grating structure, in the optical material. These planes of the interference grating structure in the holographic optical element will be described further below.

Fig. 1 shows an exemplary active bifocal lens 10 according to the invention. It should be noted that the invention is described herein for illustrative purposes using a bifocal optical lens, although an active optical lens according to the invention may have more than two optical powers. The active bifocal lens 10 is a contact lens having a first optical element 12 and a holographic optical element 14. The holographic optical element 14 is encapsulated in the first optical element 12 to form a composite active bifocal lens 10 in such a way that the holographic optical element 14 moves together with the active bifocal lens 10. The first optical element 12 provides a first optical power that corrects ametropia, such as myopia (nearsightedness). Alternatively, the first optical element 12 may be a flat lens which functions as a carrier for the holographic optical element 14. As for the holographic optical element for path modification, light enters 14' under the front

14/ is the light hologram this only _ about keno optical element -determined -in the case when

- ' of the optical element at a programmed angle, that is, at an activating angle, - which activates said optical element. Accordingly, in the case where light enters at an angle which is outside the activating angle, the holographic optical element 14 transmits completely - or substantially completely - the incoming light without - significantly modifying the light path or any modification of the light path.

> Alternatively, the holographic optical element 14 may act as a flat lens, except when the angle of incidence of the incoming light falls within a pre-programmed activation angle. When the holographic optical element 14 is activated, the scattering structures or volume grating structure programmed into the holographic optical element 14 modify the light path to provide an optical power that is

fc · different from the first optical power of the active bifocal lens 10. In addition to the activatable optical power, the holographic optical element 14 may also provide an optical power that is a result of the shape of the holographic optical element 14 and the refractive index of the material of the holographic optical . element 14 . Such additional optical power ' supplements the material of the first optical element to provide the first . optical ' power of the active "bifocal lens 10 in the event that . incoming light . enters the active bifocal lens 10 . at an angle that does not activate the holographic optical element 14 . ,

The term activation angle here refers to the angle of incidence of the incoming light, which is defined as the angle between the direction of travel of the incoming light and the normal to the surface of the holographic optical element 14, which satisfies the Bragg condition, so that the incoming light is scattered by the interference scattering grating structure in the holographic optical element 14, which will be explained in more detail below. It should be noted that the activation angle does not have to be a single value, but can be a range of angles. The Bragg condition is well known in the art and is defined, for example, in Coupled Wave Theory for Thick Hologram Gratings, H. Kogelnik, The Bell System Technical Journal, Vol. 48, No. 9, pp. 2909-2947 (December 1969). This Bragg condition can be expressed as , cos (φ-θ) = Κχ'23 .......

where K = 2π/λ, where λ is the grating period of the interference, scattering structure, Θ means the angle of incidence of the incoming light, φ means the angle of inclination of the grating and B is the mean propagation constant, which can be expressed as B = ' ' ' - j .' .

• · yes

2πη/λ, where n is the mean refractive index and λ is the wavelength of light. When the Bragg condition is met, up to 100% of the incident light can be coherently bent.

Fig. 2 further illustrates the function of the holographic optical element 14 of the active bifocal lens 10 of Fig. 1. The z-axis, which is perpendicular to the planar surface of the holographic optical element 14 and the propagation direction of the incoming light R, forms an angle of incidence σ with the z-axis. In the case where the incoming light R enters the holographic optical element 14 at an angle that falls within the range of the activation angle of the holographic optical element 14, then the incoming light R is bent by a pre-programmed interference scattering structure, i.e. a volume grating structure, of the holographic optical element 14 as outgoing light S with an exit angle q that is different from the angle of incidence σ.

Fig. 3 shows another embodiment of an active bifocal lens according to the invention. The active bifocal lens 16 is a composite lens having a first optical lens 17 and a holographic optical lens 18. Alternatively, the holographic optical lens 18 may be of such a size that it covers only the pupil of the eye. The first optical lens 17 and the holographic optical lens 18 may be manufactured separately and then joined, for example using an adhesive or thermally. Alternatively, the first optical lens 17 and

...,^ holographic_ optical_lens ^_18__ are manufactured _ _sequentially _ or simultaneously one on top of the other so that the 'product' is a composite lens. This sequential or simultaneous.concept is. particularly suitable' in the case where. the first optical lens 17 and the holographic optical lens 18- are manufactured from one base material or from two chemically compatible materials. Although the bifocal active lens 16 is manufactured in the illustrated embodiment such that it contains the first • · · · • · as the inner half.

β ··« • : :

• · · · .·· • · • · φ φ φ . φ • · · · · · · · · · optical, lens 17 and as the outer half contains a holographic optical lens 18, it is possible to produce other combinations of various optical elements within the scope of the invention.

Yet another embodiment of the active bifocal lens is a non-composite active holographic bifocal lens. In this embodiment, the active holographic bifocal lens is made of an optical material that forms a holographic optical element. The combination of the shape of the active lens and the refractive index of the material from which the holographic optical element is made provides a first optical power, and the programmed volume grating structure in the holographic optical element provides a second optical power. This embodiment of the non-composite active holographic lens is particularly suitable when the material used for the holographic optical element is a biocompatible material that does not interfere with the ocular tissue of the eye in such an undesirable way.

The term biocompatible material refers herein to a polymeric material that does not appreciably degrade or induce a significant immune response or adverse reaction of ocular tissue, such as a toxic reaction or significant irritation of the eye, for the period of time that the material is implanted into or placed in contact with the biological tissue of the patient. Preferably, the biocompatible material does not appreciably degrade or induce a significant immune response or adverse reaction of ocular tissue for at least 6 months, more preferably for at least one year, and most preferably for at least 10 years. Suitable biocompatible optical materials are highly photo-crosslinkable and photo-polymerizable materials. Suitable biocompatible materials include derivatives and copolymers of polyvinyl alcohol, polyethyleneimine, or polyvinylamine. Exemplary biocompatible materials include

• 9

9'99

9-99 99 • 9 99 which are particularly suitable for the production of the holographic optical element according to the invention are described in US patent 5,508,317 and in international patent application

PCT/EP96/00246. ' j» ¹

The holographic optical element is programmed so that it has one of the activating angles at which the holographic optical element is activated and the holographic optical element bends the incoming light in order to focus the light to the desired location.

Fig. 1 and Fig. 5. illustrate the function of the holographic optical element 21 of the composite active lens . 2Q, which includes a holographic optical element 21 that is programmed to focus light coming from a short distance. When -light- 22 coming from a distant object enters the lens at. an angle that does not activate the holographic optical element. 21, the. light 20 is focused in accordance with the optical power of the first optical element of the composite active lens 20 in combination with the optical power of the crystalline lens of the eye (not shown)' to . a focal point 21 located. on the retina,. more specifically, at the point of sharpest vision. '

For example, the first optical element 23 may have a corrective power in the range between +Ϊ0 diopters and -20 diopters. It should be noted that the holographic optical element 21 may have its own optical power, which is derived from the shape of the holographic optical element 21 and the refractive index of the material from which the holographic optical element is made. As a result, the holographic optical element 21 may contribute to the refractive optical power • ·' · » 9 4 · φ 9 «999 9 9 999 9 4 ₉ 9 ··.*»· ·· »' 4 4 4 · ·

4 4 4 4 4 4 4 ' 4 · · 4

4 4 4 9 49 4 9 4 4 ·· composite active lens 21. However, in the following, this intrinsic optical power of the holographic optical element 21 will be neglected in order to simplify the illustration of the diffraction function of the composite active lens according to the invention, since said intrinsic optical power can otherwise be easily evaluated within the scope of the invention. *

In the case where the holographic optical element 21 is not activated, the holographic optical element 21 does not prevent light 22 from traveling along the normal refractive path determined by the first optical element 23. However, when this light enters the holographic optical element 21 at an angle that activates the holographic optical element 21 (i.e., enters at the activating angle), it is bent by the holographic optical element 21.

IN

It is apparent from Fig. 5 that when incoming light enters the active lens 25 at an angle that activates the holographic optical element 26, the lens, together with the first optical lens 27 and the crystalline lens of the eye, focuses the light onto the retina, more specifically the fovea. For example, light 28 from a near object 29 forms an image 30 at the fovea if the light enters the holographic optical element 26 at an angle that is within the programmed activation angle.

The angle of incidence of the incoming light relative to the active bifocal lens, more particularly the holographic optical element of said lens, can be varied in various ways. For example, the active lens can be tilted to change the angle of incidence of the incoming light, which means that the wearer of the lens can change the angle of incidence of the light by tilting his gaze downwards while maintaining the position of his head. Alternatively, the active lens can have a position control mechanism that can

9 « 9 99 be actively controlled by the lens wearer using one or more muscles in the eye. For example, the active lens may be shaped so that its movement may be controlled by the lower eyelid. It should be noted that the actuating angle of the active lens 25 shown in FIG. 5 is exaggerated enough to easily explain the nature of the invention, and therefore the actuating angle of the active lens should not be as large as the inclined angle shown in FIG. 5. In fact, holographic optical elements suitable for use in the invention may be programmed to have a wide range of different actuating angles, consistent with programming techniques known in the holographic art. Accordingly, the amount of movement required to transition the active lens from one optical power to another optical power can be easily varied depending on the design criteria and needs of each particular lens wearer. Even when the active lens of the invention provides more than one optical power, the active lens produces visible images that are focused at any given time by only one optical power. As a result, the active lens does not produce blurred and foggy images, unlike conventional bifocal lenses, such as concentric simultaneous bifocal lenses. Attention is again drawn to FIG. 5. When the active lens is 25 is positioned to observe a near object 29 (i.e., when the angle of incidence of light coming from the near object 29 is within the range of the activating angle of the holographic optical element

6) then the light coming from the near object 29 is focused by the holographic optical element 26 together with the first optical lens 27 and the crystalline lens of the eye on the retina to the place 30 of the sharpest vision. At the same time, the angle of incidence of the light coming from the distant objects is not within the range of the activating angle of the active lens 25. Accordingly, the path of the light coming from the • · β 9 0«

0 distant objects is modified _by the holographic optical element 26, while the path of light coming from near objects is modified, i.e. bent, by the first optical lens 27 and the crystalline lens of the eye. The light coming from distant objects is therefore focused so as to form an image in a region 31 which is outside the area of the retina with the sharpest vision (outside the fovea). As a result, the focused images of near and distant objects are not concentrically or axially aligned. It has been found that the image which is formed outside the region 31 is not clearly perceived by the wearer of the active lens 25 and is easily missed by the wearer of the active lens 25 and thus included in the peripheral vision. As a result, the wearer of the lens 25 is able to clearly observe a near object 29 without this image of the near object being blurred due to interference with the . light coming from distant objects.

Similarly, when the active lens is positioned to view a distant object, for example, as in the situation shown in FIG. 4, light 22 from distant objects enters the lens at an angle that is outside the range of the activating angle of the holographic optical element 21.

Therefore, the path of this light is not influenced by the holographic optical element 21, but is only influenced by the first optical element 23 and the crystalline lens of the eye, as a result of which an image of a distant object is formed at the focal point 24.

... i.e. in the "region of the retina:- central interference. At the same time - the light coming from the near object is bent and focused by the holographic optical element 21 and ^: projected- into the --.region of the retina, which is outside the area with the sharpest vision. Accordingly, the wearer of the lens observes a clear image of the distant object without significant disturbing interference.

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··* · ··. ··· eeee with β * «· * « and i

The advantage of ‘unblurred image provided by active.

The lens of the invention is a consequence of the design of this active lens which takes advantage of the inherent anatomy of the eye. It is known that the concentration of retinal receptors outside the fovea is drastically lower than the concentration of retinal receptors in the fovea. As a result, any image focused substantially outside the fovea is not clearly perceived because the image is optically undersized by the retina in terms of the number of retinal receptors that capture the image, and the brain of the lens wearer perceives such an image as included in peripheral vision. In fact, it has been found that the visual acuity of the human eye drops to about 20/100 for objects that are only 8° outside the line of sight. With the active control concept described above, the active lens of the invention provides clear images within one optical power while simultaneously utilizing the inherent anatomy of the eye. By utilizing the inherent anatomy of retinal receptors and the ability to program different ranges of "activating" angles in the holographic opto-optical lens element, the active lens of the invention provides clear images of objects at different distances. Unlike various simultaneous bifocal lenses, the active lens of the invention provides undistorted clear images, and unlike translational bifocal lenses, the active lens of the invention can be easily designed to require only a small amount of lens movement to selectively view images at different distances.

_Holographic optical elements according to the invention can be made, for example, from polymerizable or crosslinkable materials, in particular from a liquid optical material. Suitable polymerizable and crosslinkable materials for a holographic optical element are described below. In the following text, for simplicity, only the term polymerizable material will be used, and this term will include both polymerizable and

4

9 99 • · 4

9,994 i crosslinkable material, unless otherwise expressly stated.

An exemplary method of manufacturing a holographic optical element according to the invention is illustrated in Fig. 6. Light 33 from a point source is projected onto a photopolymerizable optical material 33 (i.e., a photopolymerizable holographic element), while a collimated reference light 34 is simultaneously projected onto the photopolymerizable material 33, such that the electromagnetic waves of the light 32 and the reference light 34 form an interference scattering optical optical polymerizable and reference light 34. Preferably, the light 3.2 and the reference light 34 originate from a single light source, the light of which is split by a light beam splitter. Both the split portions of the light with the light-curable optical material 32 are modified to form a point source light 32. The point source light 32 may be generated, for example, by placing a conventional convex optical lens at a certain distance from the light-curable optical material 33 so that this light is focused to a desired distance from the light-curable optical material 33. A preferred light source is a laser source or, more preferably, an ultraviolet radiation source. Although the wavelength of the light source . depending on the type of photopolymerizable optical material used, wavelengths from 30 to 600 nm are preferably used. When the photopolymerizable optical material 33 is fully exposed and polymerized, the resulting holographic optical element , comprises a modulated refractive index structure, i.e. a bulk lattice structure of the holographic polymerizable liquid optical element, wherein

35. Furthermore, when a liquid optical material is used to produce an optical element ^, the light source material converts to a solid holographic optical material during this conversion, forming the aforementioned volume grating structure 35.

' It is apparent from Fig. 7 that the polymerized holographic optical element 36 has a focal point 38 which corresponds to the position of the point light source 32 of Fig. 6, when light 39 enters the holographic optical element 36 from the opposite side to that on which said focal point is located, said light copying or substantially copying the reverse path

- collimated. reference light 34 of Fig. 6. Fig. 6 and. Fig. 7 • illustrate - exemplary-- method of manufacturing a -holographic optical . element having a positive correction power. It is self-evident/

--- that with the application of small modifications, the above-described method can also be used for the production of holographic optical elements having a negative, corrective, power. -For example, for the production of a holographic optical- .element having a negative_____ corrective, power, a convergent light- source can be used instead of a point light- source,. which forms a focus, on the -other side- of the holographic optical element than on;which

..se·, a light source is found. Within the scope of the invention, active-multifocal lenses having different' corrective powers.' and intended for' correction " - - various. ých h' ame. tropic ...„„.conditions./™ j ajcými so_u " for example.1 ad__ myopJL.e,. ___ hyperopia,· prebyopia, regular' astigmatism, irregular stigmatism and their mutual combinations. '

For example, the corrective powers of holographic optical elements can be varied by changing the distance, position, or/and path of the point light source, while the activating «4 • · · β 9·· • ' 4 • 4*4 94 . .49 . 9« • 4 · e · eee ee

4 · ·

9 9 9 · · 4 · e 4 ee ·· e · · · • 4 ee the angle of the holographic optical elements can be changed by changing the position of the point light source .a. the reference light.

Within the scope of the invention, suitable holographic optical elements can be made of polymerizable and crosslinkable optical materials that can be relatively rapidly polymerized or crosslinked by light. A rapidly polymerizable optical material allows a periodic change in the refractive index of the optical material to be created, resulting in a bulk lattice structure being formed during polymerization of the optical material to convert it to a solid optical material. Preferably, suitable polymerizable and crosslinkable optical materials are selected from biocompatible optical materials, and preferably, suitable optical materials are selected from liquid, biocompatible optical materials that polymerize or crosslink to form a non-liquid, solid optical material. .element- having - a defined shape -and- in < -5 minutes or less than ^: 5 minutes, more preferably in 3 minutes or less than 3' minutes and even more preferably in 1 minute or less than . 1 ; minutes and most preferably in 30 seconds or less than,

30'seconds, for example within. 5 to 30 seconds.. The duration of the crosslinking - or polymerization is ..determined by placing the 'crosslinkable or- polymerizable optical material between ' two 'quartz . slides, which· have ’. dimensions of microscopic 'slides.’ 'and are spaced apart from each other by means of a spacer at a distance of 10-0 μτη.

A sufficient amount is deposited on the first quartz slide.

optical material to form a circular - drop having a diameter of about-. ,14 . mra and optical., material is covered with a second quartz slide. Alternatively- can.’ be used- spacer, to 'create'' a cylindrical space' between ; both quartz ’ ’ slides for the optical material.. The optical material between the two, quartz slides, is then irradiated with a 200 W medium pressure · · · · ·· ft · · · β βίϊ e . e e « · · • · ^ · · · · · · · · · · <. « • ·· · · · · · · · · · · ·» ·· ·» «· mercury discharge lamp, which is placed at a distance of 18 cm above said upper- quartz slide;

An exemplary group of biocompatible polymerizable optical materials suitable for use in the present invention is described in U.S. Patent No. 5,508,317. A preferred group of polymerizable optical materials described in said U.S. Patent No. 5,508,317 are materials which have

1.3-diol. 'basic- structure in which a certain percentage of the 1,3-diol' units have been modified to

1.3- dioxane having a radical in the 2-position, which is polymerizable but not polymerized. This polymerizable optical material is preferably a polyvinyl alcohol derivative having a weight average molecular weight M _w of at least about 2,000, which has from about 0.5 to about 80%, based on the number of hydroxy groups of the polyvinyl alcohol units of general formula I.

in κr e rém '. ' ' ™ ,

R represents a lower alkyne group containing up to 8 carbon atoms,

R ¹ represents a hydrogen atom or a lower alkyl group and R ² represents an olefinically unsaturated, electron-withdrawing group.

a copolymerizable group having preferably up to 25 carbon atoms, wherein R ² for example represents an oleinically unsaturated acyl group of the general formula R ³ -CQ-, in which - >

R ^J represents an oleinically unsaturated copolymerizable group having 2 to 24 carbon atoms, particularly preferably 2 to 4 carbon atoms.

Exemplary oleic unsaturated copolymerizable groups _A include ethenyl, 2-propenyl, 3-propenyl, 2-butenyl, hexenyl, octenyl and dodecanoic groups _.

In a preferred embodiment, the group R ² represents a group of general formula II ':·,·/,' -.

r.-CO-NH- (R ⁴ -NH-CO-O) -r ⁵ -o] "-cc-r ^! Τΐΐ) in which'·'- p means 0 or 1, preferably. 0, q means 0 or 1, preferably- 0,

R ⁴ and R ⁵ each independently represent a lower alkyl group having 2 to 8 carbon atoms, an arylene group having 6 to 12 carbon atoms, a saturated divalent cycloaliphatic group having 6 to 10 carbon atoms, an arylenealkylene or alkylene group.

• ·

an arylene group having 7 to 14 carbon atoms or an arylenealkylenearylene group having 13 to 16 carbon atoms, and

R ^J has the meaning given above.

The lower alkylene group R preferably contains up to 8 carbon atoms, which group may be a straight-chain or branched group. Suitable examples of this group include octylene, hexylene, pentylene, butylene, propylene, ethylene, methylene, 2-propylene, 2-butylene and 3-pentylene. Preferably, the lower alkylene group R has up to 6 and particularly preferably up to 4 carbon atoms. Preferred lower alkylene groups R are in particular methylene and butylene. R ¹ preferably represents a hydrogen atom or a lower alkyl group having up to 7, in particular up to R ¹ represents a hydrogen atom.

Carbon atoms, while

As regards R ⁴ and R ⁵ , the lower alkylene group R ⁴ or R ⁵ preferably contains 2 to 6 carbon atoms, which group is preferably a straight carbon chain group. Suitable examples of the zeso group include propylene, butylene, hexylene, dimethylethylene and particularly preferably ethylene.

Arylene group. R ⁴ or R ⁵ preferably represents a phenylene group which is unsubstituted or substituted by a lower alkyl group or a lower alkoxy group and which in particular represents a 1/3-phenylene group or

1,4-phenylene group or methyl-1,4-phenylene group. '·

The saturated divalent cycloaliphatic group R or R ⁵ ' is preferably a cyclohexylene group or a cyclohexylene(lower alkyl)ene group, for example a cyclohexylenemethylene group, which is unsubstituted or substituted by one or more methyl groups, such as a trimethylcyclohexylenemethylene group, for example a divalent isophorone group. The aryl unit of the alkylarylene group or arylene.alkylene group R ⁴ or R ⁵ is preferably a phenylene group, which is unsubstituted or substituted by a lower alkyl group or a lower alkoxy group, the alkylene unit of which is preferably a lower alkylene group, such as a methylene group or an ethylene group, especially a methylene group. Such groups R ⁴ or R ⁼ are therefore preferably a phenylenemethylene group or a methylenephenylene group. '.' , . .

The arylenealkylarylene group R ⁴ or R ⁵ is preferably a phenylene (lower alkyl) phenylene group containing up to 4 carbon atoms in the alkylene unit, for example a phenyleneethylenephenylene group. The groups R ⁴ ' and -R' ³ each _ independently ·' preferably mean_ a lower alkylene group containing' 2 to 6 carbon atoms, a phenylene group which is unsubstituted or substituted by a lower alkyl group, a cyclohexylene group or a cyclohexylene (lower alkyl) ene group which is ' unsubstituted or substituted by a lower alkyl group,' a phenylene (lower alkyl) ene group, a (lower alkyl) enephenylene group or a phenylene (lower alkyl) enephenylene group.

• · • ·

Polymerizable optical materials of general formula I are, for example, prepared by reacting polyvinyl alcohol with a compound of general formula III.

R’

AND

R

AND

About \h

AND

RN .R ,(HD 'R in which R, R ¹ and- R ^z have the above meanings and R' and R each independently represents a hydrogen atom,/ lower ' alkyl group or lower alkanoyl group, such as -an acetyl group or propionyl group. Preferably, about 0/5 to about 80%, more preferably about 1 to about 50% and most preferably about 2 to about 15 -%, of the hydroxyl groups of the resulting polymerizable optical material are replaced by a compound of general formula II,I.

Suitable polyvinyl alcohols for ^the derivatized polyvinyl alcohol of the invention have a weight average molecular weight of about 2,000 to about 100,000, preferably 10,000 to 300,000, more preferably 10,000 to 100,000, and most preferably 10,000 to 100,000.

- 10,000 to 50,000. These polyvinyl alcohols contain less than about 50%, preferably less than about 20%, of unhydrolyzed alcohols. vinyl alcohols. Polyvinyl alcohols. contain up to about 20%, preferably up to about 5%, _of one or more _copolymeric units, such as ethylene units, propylene units, acrylamide units, methacrylamide units, dimethacrylamide units, ^hydroxyethyl methacrylate units, methyl methacrylate units, methyl acrylate units, vinyl pyrrolidone units, hydroxyethyl acrylate units, allyl alcohol units and styrene units.

Polyvinyl alcohol derivatives polymerize in a solvent by the mechanism of crosslinking under the action of light, for example using an ultraviolet laser, to form a holographic optical element. A suitable solvent here is any solvent that dissolves polyvinyl alcohol and vinyl comonomers. Exemplary solvents are water, ethanol, methanol, propanol, dimethylformamide, dimethyl sulfoxide and mixtures thereof. In order to facilitate the course of the light-crosslinking polymerization process, it is desirable to add a _{photoinitiator} capable of initiating radical crosslinking. Examples of photoinitiators that can be suitably used in the invention are benzoin methyl ether, 1-hydroxycyclohexylphenyl ketone, Durocure 1173 photoinitiator and Irgacure photoinitiator. Preferably, about 0.3 to about 2.0% of photoinitiator is used, based on the total weight of the polymerizable formulation.

Within the scope of the invention, suitable concentrations of the polyvinyl alcohol derivative in the solvent for the production of the holographic optical element are preferably between about 3 and about 90% by weight, more preferably between about 5 and 60% by weight, and most preferably between about 10 and 50% by weight, especially in the case where the holographic optical element is intended to be used as an ophthalmic lens. ... _/

Another group of exemplary biocompatible polymerizable optical materials suitable for use in the present invention is described in U.S. Patent Application Serial No. 4,111,111.

Such suitable optical materials include

08/875,340 P.CT/EP96/00246).

.derivatives of polyvinyl alcohol, polyethyleneimine or polyvinylamine containing an azalactone residue, which contain from about 0.5 to about 80%, based on the number of hydroxyl groups in polyvinyl alcohol or the number of imine or amine groups in polyethyleneimine or polyvinylamine, of units of the general formula IV and V . —-ch ₂ -ch ₂

R4 in ° i

R—<—R, (TV)

-ch-ch ₂ -nc=o

I. '

R—c—R (V)

OR II I ³

NH—C—C=CH

OR II -I ³ ..

NH—C—C—CH in which. R _x and . R ₂ independently hydrogen, alkyl group atoms, aryl group · wherein, these groups .· substituted;' R. means

-3 group, containing ' 1 . to methyl - -group;-.. and . ,R, .

one on the other'means- an atom containing 1' to - 8 carbons or a cyclohexyl group, are 'unsubstituted- or a hydrogen atom or an alkyl group

8''carbon'' atoms, preferably

:.name.-nái_ můs.tek.k_-.Q^ ₌ ,^ ₌ n,eb,o _iS! preferably the bridge -O-. Polyvinyl alcohols, polyethyleneimines and polyvinylamines suitable for use in the invention have a number average molecular weight of about 2,000 to about 1

000 C00, .preferably about 10,000- to 300,000, .more preferably 10,000 to 100,000 and most preferably 10,000 to 50,000.

·· ·· »· ·· ·· • ·· · *· · »· « . ·.· 4 « »»· « · » * » · β ·· ·· · «· » * . . . .· · · ··.» ...» ·· ·· ·· ·· ··

A particularly suitable polymerizable optical material is a water-soluble polyvinyl alcohol derivative having from about 0.5 to about 80%, preferably from about 1 to about 25%, more preferably from about 1.5 to about 12%, based on the number of hydroxyl groups in the polyvinyl alcohol, of units of formula IV, in which R1 and _R2 are methylene groups, R1 is a hydrogen atom and _R4 is an -O- bridge (which is an ester bond).

.'.'., í ·.

Polymerizable optical materials of general formulas IV and V can be prepared, for example, by reacting an azalactone of general formula VI.

R.

?3 _Z N·—c—R \ ²

CH—C—C ² \ o—c=o (VI) in which R _ir R ₂ and R. have. the above meanings, -with polyvinyl alcohol, polyethyleneimine or polyvinylamine at an elevated temperature ranging from about 55. to '75 ° C, in ^; a suitable 'organic solvent and optionally· in the presence of a suitable catalyst. Suitable) solvents here are those solvents which dissolve the basic.polymer chain, these solvents - including aprotic polar solvents, for example formamide, dimethylformamide, triamine -hexamethylphosphoric acid, -dimethylsulfoxide, pyridine, nitromethane,.- acetonitrile, nitrobenzene, ' chlorobenzene, trichloromethane .and dioxane. Suitable catalysts also include tertiary amines, for example. triethylamine., and. organotin salts,·for example dibutyltin dilaurate.) .

• φ ·

·· ·· *· ·· · .· ♦ · ♦ * * , · φ φ φ c β ·· · '·.· ·« « ·· ·' · <······ , ····»·.»··'· · . . /In addition to the azalactone residue, optical materials containing the azalactone residue may also contain other hydrophobic and hydrophilic vinyl comonomers, depending on the desired physical properties of the polymerized holographic optical element. Examples of suitable hydrophobic comonomers include alkyl acrylates and alkyl methacrylates containing 1 to 8 carbon atoms in the alkyl residue, alkyl acrylamides and alkyl methacrylamides containing 3 to 18 carbon atoms in the alkyl residue, acrylonitrile, methacrylonitrile, vinyl C^-C^-alkanoates, alkenes. containing '2 to 18' carbon atoms, ' styrene, ' vinyl alkyl ethers, - C ₂ -C ₁₀ -perfluoroalkyl acrylates. -and methacrylates, C k -C ₁₂ -perfluoroalkyl ethylthiocarbonylamino- ethyl acrylates and methacrylates,. acryloxy- and methacryloxy-alkyl siloxanes, N-vinylcarbazole,' alkyl esters.

malonic, fumaric, itaconic and other acids containing 1 to 12 carbon atoms in the alkyl radical.

Examples of suitable hydrophilic comonomers include hydroxyalkyl acrylates and methacrylates, acrylamide, methacrylamide, methoxylated acrylates and methacrylates, hydroxyalkyl amides.

N-vinylsuccinimide, and methacrylamides, N-vinylpyrrolidone,

N-vinylpyrrole, vinylpyridine, acrylic acid, methacrylic acid, and the like.

Optical materials containing an azalactone residue are crosslinked with a polymer in a solvent by a light-induced crosslinking mechanism, for example, using an ultraviolet laser, to form a holographic optical element. A suitable solvent is any solvent that dissolves the polymer backbone of the optical materials. Exemplary solvents include aprotic solvents as described above in connection with azalactone modification, for example water, ethanol, methanol, propanol, glycols,

9 9 9 9 ♦' • 9 · · · · · • · · · · · • ti titi ·· glycerols, dimethylformamide, dimethylsulfoxide and mixtures thereof. In order to facilitate the course of the photo-crosslinking polymer process, it may be desirable to add a photoinitiator capable of initiating radical crosslinking. Exemplary photoinitiators suitable for use in the invention are benzoin methyl ether,

1-hydroxycyclohexylphenyl ketone, Durocure 1173 photoinitiator and Irgacure photoinitiator. Preferably, about 0.3 to about 2.0%, based on the total weight of the polymerizable formulation, of the initiator may be used. Within the scope of the invention, suitable concentrations of the optical material containing the azalactone moiety in the solvent are preferably between about 3% and about 90% by weight, more preferably between about 10% and about 50%, especially when the holographic optical element is intended to be used as an ophthalmic lens.

- Yet another group of bi-compatible polymerizable optical materials suitable for use in the present invention is a functionalized copolymer of vinyl lactam and at least one other _vinyl monomer, which is a second vinyl monomer. This copolymer is functionalized with a reactive vinyl monomer. The vinyl lactam of the present invention is a 5- _to 7-membered lactam of the general structure VIT

Rb

Rc

(VII) in which í< means an alkylene bridge containing 2 to 8 carbons ·· ·· ·· ·· • - · * * · « » e 9 β·· · · · <

atoms, ,

_R0 represents a hydrogen atom, an alkyl group, an aryl group, an aralkyl group or an alkaryl group, preferably a hydrogen atom, a lower alkyl group containing up to 7 carbon atoms, an aryl group containing up to 10 carbon atoms or an aralkyl or alkaryl group containing up to 14 carbon atoms, and

R _c represents a hydrogen atom or a lower alkyl group containing up to 7 carbon atoms, preferably a methyl group, an ethyl group or a propyl group. . .

Exemplary vinyl lactams suitable for use in the present invention include N-vinyl-2-pyrrolidone, N-vinyl-2-caprolactam, N-vinyl-1- ^; 3-methyl-2-pyrrolidone,

N-vinyl-3-methyl-2-piperidone·,

N-vinyl-3-methyl-2-caprolactam, _i

N-vinyl-4-methyl-2-pyrrolidone, ' .

N-vinyl-4-methyl-2-caprolactam,

N-vinyl-5-methyl-2-pyrrolidone,

N-vinyl-5-methyl-2-piperidone,

N-vinyl-5,5-dimethyl-2-pyrrolidone,

N-vinyl-3,3,5-trimethyl-2-pyrrolidone,.

N-vinyl-5^methyl-5-ethyl-2-pyrrolidone, . ,

N-vinyl-3/4', 5-trimethyl-3-ethyl-2-pyrrolidone, - ' .

N-vinyl-6-methyl-2-piperidone, N-vinyl-6-ethyl-2-piperidone, N-vinyl-3,5-dimethyl-2-piperidone, .· ’

N-vinyl-4,4-dimethyl-2-piperidone,

N-vinyl-7-methyl-2-caprolactam,

N-vinyl-7-ethyl-2-caprolactam,

N-vinyl-3,5-dimethyl-2-caprolactam, N-vinyl-4,6-dimethyl-2-caprolactam,

N-vinyl-3,5,7-trimethyl-2-caprolactam and mixtures thereof.

···· ·· • *ee • ·.

Preferred vinyl lactams are heterocyclic monomers of the general formula VII containing 4 to 6 carbon atoms in the heterocyclic ring. More preferred vinyl lactams have a heterocyclic monomer of the general formula VI.I, in which the heterocyclic ring contains 4 carbon atoms and R _o and R _c independently of each other represent a hydrogen atom or lower alkyl radicals. A particularly suitable vinyl lactam is

N-vinyl-2-pyrrolidine. Suitable second vinyl monomers include functional vinyl monomers which have, in addition to the vinyl group, a functional group, for example, a hydroxy group, an amino group, an amino group substituted by a lower alkyl group, a carboxyl group, an esterified carboxyl group, an alkoxycarbonyl group, an epoxy group or a sulfo group (-SO..H). This functional group in the molecule remains when the vinyl group of the second ^vinyl monomer is reacted with a vinyl lactam to produce a polymer chain and can be used to modify or functionalize said polymer.

^Suitable functional vinyl monomers include hydroxyl-substituted alkyl acrylates and methacrylates, ethoxylated alkyl acrylates, alkyl acrylates substituted acrylates and methacrylates, epoxy (lower) and methacrylates, epoxy cycloalkyl (lower) and methacrylates, hydroxyl-substituted lower alkyl acrylamides and methacrylates, hydroxyl-substituted ^lower alkyl vinyl ethers, amino- or hydroxy-substituted styrenes, sodium ethylene sulfonate, sodium styrene

2-acrylamido-2-methylpropanesulfonic acid, acrylic acid, methacrylic acid, amino-(lower alkyl)- and, alkylamino(lower alkyl)acrylates and methacrylates, acryloxy- and

9' 9 • 9

9

3-2 methacryloxy(lower alkyl)maleimides and allyl alcohol. As used herein, the term lower alkyl refers to an alkyl group containing up to 7 carbon atoms, preferably up to 4 carbon atoms. Particularly suitable vinyl functional monomers include

2-hydroxyethyl methacrylate, 3-hydroxypropyl methacrylate, acrylic acid, . 4-aminostyrene,

3-methacryloxymethyl-7'-oxabicyclo[4'..1.0]heptane, ·

N-methacryloxyethylmaleimide,· glycidyl methacrylate, ethyl methacrylate ammonium^hydrochloride -a.

···' propyl methacrylate ammonium hydrochloride.

The copolymer of vinyl lactam and the second vinyl monomer is prepared in a manner known per se in the presence or absence of a solvent. This copolymer may be a random polymer. A method for preparing a random polymer is described, for example, in the patent document.

5,712,.35.6. A suitable solvent dissolves said monomers and . 'polymer prepared' from these. monomers and' is substantially inert.·, towards these monomers and ' this· polymer. ' Examples of ' suitable solvents include water, alcohols, for example .. ——methanol,, ethanol and propanol, carboxylic acid amides, for example. . dimethylformamide and' dimethylsulfoxide, ethers, • for example·, diethyl ether, tetrahydrofuran and diglymes, and mixtures thereof. . - .

Suitable copolymers have an average molecular _{weight of} preferably 10,000 to 300 _.

000, more preferably. 10,000 to. .100,000. and most preferably 10,000 ¹ to 50- 000.· . - ' . '

The copolymer is further modified with a reactive vinyl monomer to obtain a rapidly crosslinkable polymer. Suitable reactive vinyl monomers have, in addition to

vinyl; groups ..another reactive moiety that reacts with a functional group present in the copolymer to form a covalent bond while retaining the vinyl group in the monomer. Examples of suitable reactive, vinyl monomers include hydroxy-substituted alkyl acrylates and methacrylates, hydroxy-substituted (lower alkyl) acrylamides' and methacrylamides, 'hydroxy-substituted'. (lower alkyl) vinyl ether, 2-acrylamido-2-methylpropanesulfonic acid, amino-(lower alkyl)•and mono (lower alkyl) amino (lower alkyl) acrylates.. and methacrylates,· methacrylates,''methacrylates, containing 3 allyl alcohol, epoxy-(lower alkyl) acrylates and isocyanato-(lower ' alkyl) acrylates ' and •vinyl unsaturated carboxylic acids of up to 7 carbon· atoms, as well as the chlorides and anhydrides of these· acids, amino-, ' hydroxy- ' . or· isocyanato-substituted styrenes.'and' ^: ' epoxycycloalkyl (lower alkyl) acrylates and methacrylates. Preferred reactive vinyl monomers include hydroxyethyl acrylate and methacrylate, hydroxypropyl acrylate and methacrylate, isocyanatoethyl acrylate and methacrylate, acrylic and methacrylic acid chloride, ethyl methacrylate ammonium hydrochloride, and propyl methacrylate ammonium hydrochloride.

The functionalized copolymer is typically crosslinked or polymerized in a solvent by a crosslinking mechanism by the action of light, for example using an ultraviolet laser, to form a holographic optical element, although said copolymer may be crosslinked or polymerized in the absence of a solvent. A suitable solvent is any solvent that dissolves the basic structure of said polymer. Exemplary solvents include water, alcohols such as methanol or ethanol, carboxylic acid amides, dimethyl sulfoxide, and the process may be assisted by, for example, dimethylformamide and mixtures thereof. The crosslinking photoinitiator can initiate radical crosslinking. Exemplary photoinitiators suitable for use in the present invention include benzoin methyl ether, 1-hydroxycyclohexylphenyl ketone, Durocure 1173, and Irgácure 2959. Preferably, about 0.3 to about 2.0%, based on the total weight of the polymerizable formulation, of photoinitiator is used. In the present invention, suitable concentrations of functionalized vinyl lactam polymer in the solvent preferably range from about 3 to about 90% by weight, more preferably from about 5 to 60% by weight, and most preferably from about 10 to about 50% by weight, especially when the holographic optical element is intended to be used as an ophthalmic lens.

Another group of holographic optical elements for use in the invention can be made from a conventional or other recording medium for bulk transmission holographic optical elements. As already mentioned in connection with polymerizable materials for holographic optical elements, point source light and collimated reference light are projected onto a recording medium for holographic optical elements in such a way that the electromagnetic waves of the point source light and the collimated reference light create interference grating structures in said medium. These interference scattering structures, forming a bulk grating structure, are thus recorded in the holographic optical element medium. When the recording medium is

........... medium.,, pro,ho logr af ic . o p t i c.... .elements , fully ./. exposed, .

The recording medium for holographic optical elements is developed in accordance with a known method of developing holographic optical elements. Suitable recording media for transmission holographic optical elements include commercially available recording materials or plates for holographic photography, such as bichromatic gelatins. These recording materials for holographic photography are

·· . ··' ·· ·· ·· ’ ·!·· ·· ·· ·· ·· ·· ' . 35 commercially available from various manufacturers, including, for example, Polaroid Corporation. Other holographic media suitable for use in the invention are, for example, described in international patent application PCT/US96/.15600 and in . patent document US 5,453,340.. In the case where photographic recording materials are used for holographic. optical elements, the possible toxic effect of these materials on the ocular environment must be considered. Thus, when a conventional holographic photographic material is used for a holographic optical element, it is advantageous for the holographic optical element thus obtained to be encapsulated in a biocompatible optical'

- . material. Suitable biocompatible optical 'materials for encapsulating . such holographic optical' elements ( include optical materials that are suitable for, the first optical element of the active lens according to the invention, such materials will be described below.'' · . ¹ ''

As is known in the field of ophthalmic lenses, an ophthalmic lens should have a small thickness, thereby increasing the level of comfort for the wearer of the lens. Accordingly, a dimensionally thin holographic optical element is preferred within the scope of the invention. However, in order to provide a holographic optical element having a high diffraction efficiency, the holographic optical element must be optically strong, meaning that light is bent by more than one plane of the interference scattering structure. One way to obtain an optically strong and simultaneously 'dimensionally- thin holographic optical element' is "·. · · ·· programming of the interference scattering structure-,-, in .. direction, . ,,, ,, which is inclined . with respect to- the length of the holographic · optical' element .i Such an inclined volume grating structure causes,

..that the holographic optical element..has a large angular deviation between the angle of incidence of the incoming light and the angle of exit of the outgoing light. However. a holographic optical element having a large angular deviation may not be particularly suitable for an optical lens. For example, when . such ► ·· • · '9 44«

44. 44

4 « β 4 44 4

4 · 4

4 4 4

44

4 4 4 4 4 4 4 holographic optical element used in the eye lens and .when the holographic optical element .is activated, the active line of sight is significantly deviated from the normal, straight line of sight.

In a preferred embodiment of the invention, this angular limitation in the construction ^of a holographic optical element is solved by using a multilayer holographic optical element, in particular a two-layer holographic optical element.

In Fig. '8, an exemplary, multilayer, holographic optical . element . 40 according to the invention is shown. Two dimensionally thin

- holographic .· optical elements having a large, angular- deviation are combined' into mutual combination for the purpose of obtaining a dimensionally thin holographic optical element having a small angular deviation. .Said- multilayer holographic' optical, element- ' 40 comprises' a dimensionally . thin first /-holographic-· optical' element 42 -and- a dimensionally thin ' second holographic optical' element- .44 . .The first holographic optical element 42 is programmed' to/bend incoming light in such a way, - . that.- when -light enters this holographic 'optical element at an activating angle of incidence and,· then- the outgoing light leaves the first holographic optical element' at . an exit angle θ3 which is greater than the angle of incidence, a, as seen in FIG. 8A. Preferably, the first holographic optical element 42 has a thickness of about 10 to about 10 μm, more preferably about 20 to about 90 μm, and most preferably about 30 to about

... 5.0 .|Lim.._... Second, hplp_gra.fi __op_.t icky ^pr'vek 44 .je, pró_qr.amová ^; n.

so that it has an activating angle of incidence jj which is identical to the exit angle J3 of the first holographic optical element

42. In addition ^, the second holographic optical element 44 is programmed to focus incoming light into the focal point 46 when the light enters at an activating angle β. ¹ . . .

♦ · · ·'··· ♦ ·

Fig. 8B shows a second holographic element 44. Preferably, the second holographic optical element 44 has a thickness of about to about 100 μm, more preferably about 20 to about 90 μm, and most preferably about 30 to about 50 μm.

When the first holographic optical element 42 is placed next to the second holographic element 44 and the incoming light · í · . · . .

is fed at an angle that corresponds to the activation angle - ct_ of the first holographic element - 42., then the light emerging from the 'multilayer holographic optical element is focused to the focal point' 4.6 . Using. . the multilayer

- a holographic optical element can be obtained, a dimensionally thin holographic optical element having 'high diffraction efficiency and small angular deviation. In addition to the advantages of. . high ' diffraction efficiency ^: and small angular, deviation', the use of a multilayer -holographic optical provides further advantages, .which, .include' correction of dispersive aberration and chromatic aberration. A single holographic optical element can- produce, images having -dispersive and chromatic aberration because visible light -is made up of .a spectrum of electromagnetic , .waves having -different wavelengths and differences in-- -wavelengths can cause these electromagnetic waves"'to be bent by the holographic .optical 'element' differently

- way. It has been found that a multilayer, in particular a two-layer, holographic optical element, is capable of correcting said . . aberrations which . can _: 'be caused' . 'by a single-layer holographic optical element. Accordingly _, a multilayer. -holographic - -optical - . element .. . advantageous .

.holographic optical component of the ‘active lenses’ according to the invention. ; Within the scope of the invention, the holographic optical elements according to the invention preferably have a diffraction efficiency of at least 70%, more preferably at least 80% and most preferably at least •0 • ♦ · ·· • ·. 0

• 0

0' • ··

1 «

. % for all or substantially all wavelengths of the visible light region. Particularly suitable holographic optical elements for use in the invention have a diffraction efficiency of 100% for all wavelengths of the visible light region.- However, holographic optical elements having a diffraction efficiency lower than that specified above can also be used in the invention. In addition, advantageous holographic optical elements according to the invention have a sharp transition angle between the activated and non-activated states and not gradual transition angles, as a result of which activation and deactivation can be achieved only by a small movement of the active lens, whereby no or only minimal transition images are formed during the movement between the activated and deactivated states. . . ’ •As regards the first optical material of the active lens, optical? material suitable for 'hard' lenses, for gas permeable lenses or for hydrogel lenses. Suitable polymeric materials for the first optical element of active ophthalmic lenses include hydrogel materials, rigid gas permeable materials, and rigid materials known to be useful for the manufacture of ophthalmic lenses, for example contact lenses. Suitable hydrogel materials typically have a cross-linked hydrophilic network and contain about '35 to about 75 - %' by weight of water, based on the total weight' of the hydrogel material. Examples of suitable hydrogel materials " .....are ___________ ' copolymers ... '......__ containing /

2-hydroxyethyl methacrylate and at least one other comonomer, such as 2-hydroxyacrylate, ethyl acrylate, methyl methacrylate, vinvipyrrolidor, N-vinyl acrylamide, hydroxypropyl methacrylate, isobutyl methacrylate, styrene, ethoxyethyl methacrylate, methoxytriethylene glycol methacrylate, glycidyl methacrylate, diacetone acrylamide, vinyl acetate, acrylamide,

» ·· • « » «ee ·· ·· » · · • · ·*· • · · « • · · « hydroxytrimethylene acrylate;, methoxymethyl methacrylate, acrylic acid;, methacrylic acid, glyceryl methacrylate and dimethylaminoethyl acrylate. Other suitable hydrogel materials include copolymers containing methylvinylcarbazole or dimethylaminoethyl methacrylate.' Another group of suitable hydrogel materials includes polymerizable materials such as modified polyvinyl alcohols, polyethyleneimines and polyvinylamines, which are. for example, described in patent document US 5,508,317 and in international patent application. PCT/EP96/01265. Still another group. of very suitable hydrogel materials includes·' silicone copolymers- described ' in international patent application PCT/EP96/01265. Solid gas permeable materials which are suitable for use in the invention include crosslinked siloxane polymers. The network of such polymers has incorporated therein suitable crosslinking agents, such as, in particular, ethylene glycol diacrylate, pentaerythritol tetraacrylate and acrylates or methacrylates or vinyl compounds, such as N-methylaminodivinylcarbazole.

N,N'-dimethylbisacrylamide, trihydroxypropanetriacrylate, other similar 'polyfunctional'

- Suitable solid materials include acrylates, for example methacrylates, diacrylates and dimethacrylates, pyrrolidones, styrenes, amides, acrylamides, carbonates, vinyls, acrylonitriles, sulfones - and similar compounds. Of the suitable materials mentioned, hydrogel materials are particularly suitable for use in the present invention. _____ _________ _ ' __

In the holographic invention, the first optical element and the optical element may be laminated or the holographic optical element may be encapsulated in the first optical element to form an active lens in the case where a composite active lens is to be obtained. In addition, in the case where the '· • 4 ··

Β · · • 4 ·· • » 4 4 • ·4 <

· ·4 · produces an ophthalmic active lens using a non-biocompatible holographic optical element, this holographic optical element is preferably encapsulated in a first optical element, so that said non-biocompatible holographic optical element does not come into direct contact with the ocular environment and cannot adversely affect the health of the cornea in the long term. Alternatively, in accordance with what has already been stated above, the active lens can be made of a biocompatible holographic optical element, so that the holographic optical element can provide both the diffractive and refractive functions of the active lens. - - · ,· '

Fig. 9 shows another embodiment of the invention. A bifocal spectacle lens 50 is formed by laminating a layer of first optical material 52 having a first optical power, which provides the first optical power, and a layer of holographic optical element 54, which provides the second optical power. Both layers are manufactured separately and then bonded, for example thermally or using an adhesive.

— —The composite lenses thus obtained can then be machined so that they can be fitted into frames to obtain a pair of bifocal lenses in the final form of spectacles. The first optical material 52 is a conventional optical material.

- , a material that is used to make eyeglass lenses.,, for example ' x glass, ^; polycarbonate, polymethyl methacrylate, - while the holographic optical element 54 is- formed ' from any .„..holographic optical material,......--- kzeri can be programmed ..in order to * focus the incoming, light in the manner already described above. Alternatively, bifocal - lenses can be made - from - a shaped holographic optical element,. so that the optical shape of the .holographic optical element provides refractive power in the case when the holographic optical element is not activated, and the volumetric ·· • · ·

999

4 '· · • · · ···* 4· ·* • · · • β · · ♦ »9 · • 4 « · »4 4 4

9 4 4 <9 4

4 · 4

4 9

9 9 ·

The 9« grating structure provides ^diffraction power when the holographic optical element is activated.

The multifocal optical lens of the invention can be actively and selectively controlled to achieve one desired optical power at a given time without or substantially without optical interference from other optical powers of the lens, which is not possible with conventional bifocal lenses. In addition, the programmable nature of the holographic optical element of the active lens makes this lens very suitable for correcting astigmatism conditions that are not easily corrected by conventional correlative optical lenses. For example, the active lens can be programmed to correct uneven or distorted corneal curvature in the presence of irregular astigmatism, which is achieved by specifically adjusting the configuration of the point source light and the reference light during the actual manufacture of the holographic optical element. _____ The invention will be explained in the following part... using.

specific examples of its implementation, these examples being of an illustrative nature only and in no way limiting the scope of the invention, which is clearly defined by the patent claims.

Examples of embodiments of the invention __ ·

Example 1

About 0.6 ml of the monomer composition for the production of Nelfilcon A lenses is introduced into the middle part of the lower half of the mold, t

44 ·* ·*

4 4 4 4 · e e β β · 4 ·4 * • 4 4*44 · 4 ·

4*4* 4444 *4 ·· ·· • 4 βββ whereupon the upper mold half is placed on the lower half, thereby forming a mold assembly for manufacturing lenses. The upper mold part. does not touch the lower mold part, with the two mold parts being spaced apart by about.0.1 mm. Both. mold halves are made of quartz and are masked with chrome except for the central circular lens part having a diameter of about 15 mm. The monomer composition Nelficon. is a product formed by a crosslinkable. modified- -polyvinyl alcohol which contains about 0.48 - mmol/g. of an acrylamide crosslinking agent. Polyvinyl alcohol contains about- 7.5 mol.% acetate. Nelficon A has a solids content of about 31% and contains about 0-, 1% of the photoinitiator Durocure 1173. The closed mold assembly is then placed under. laser assembly. This laser assembly provides two coherent collimated UV laser beams having a wavelength of 351 nm, one of which passes through an optical convex lens to form a focal point 500 mm from the closed lens assembly. Said focused light serves as a point source light. The angle subtended between the light paths of the point source and the reference light is about 7°. Said laser assembly provides a holographic optical element having an added corrective power of 2 diopters. Said monomer composition is exposed to 0.2 W laser beams for about 2 minutes to achieve complete polymerization of said composition and to achieve interference scattering patterns. Given that. The entire mold, except for the central lens portion, is masked, the monomer composition in the central circular portion of the mold is exposed to light from a point source and a reference light, and the polymer is then exposed. The mold assembly is then opened, with the formed lens adhering to the upper mold half. The Nelfilcon A composition is reintroduced into the central portion of the lower mold half, after which about 0.06 ml of the monomeric upper mold half with the formed lens is deposited on the lower mold half. The upper and lower mold halves are separated by 0.2 mm.

•.

offset. The closed mold assembly is again exposed to the aforementioned laser assembly, except that the conventional optical lens is removed from the above-described illumination assembly. The monomer composition is thus re-exposed to the laser beams for about 2 minutes to achieve complete polymerization of the monomer composition and the formation of a second layer of interference structures. The resulting composite lens has an optical power derived from the lens shape and the refractive index of the material from which the lens is made, and an activatable additional corrective power of +2 diopters.

Example- 2

110 g of polyvinyl alcohol (Mowiol 4-88, which is available from Hoechst AG and has a degree of hydrolysis of 87.7% and a Mw (g/mol) of about 31,000) are dissolved at 90°C in 440 g of deionized water and the resulting solution is cooled to 22°C. 100.15 g of a 0.6% aqueous solution of

-_ methacrylamideacetalaldehyde dimethyl acetal, 38.5._g concentrated hydrochloric acid. (-37% p.a.,Merck) and .44.7 g deionized water. The obtained .mixture' is stirred at .room temperature, for 22 hours, after which .'its pH is adjusted to 5% sodium hydroxide solution. The solution is then diluted with 3. liters of deionized water, filtered and subjected to ultrafiltration using a 1-KD-Omega membrane produced by the company. 'Filtron, after which the solution is concentrated. '666 g of a 17.9% solution of 'methacrylamideacetalaldehyde-1,3-acetal of polyvinyl alcohol having a viscosity of 0.210 Pa.s.' According to NMR analysis, 11 . . mol.% of hydroxyl groups acetalized and 5 mol.% acetylated, whereby concentration of the aqueous polymer solution under reduced pressure and with air sparging gave a 30.8% solution having a viscosity of 3.699 Pa.s.

i • · • e

To the 30.8% solution is added 0.7%, based on the polymer content, of Durocure 1173. The solution obtained is then introduced into a transparent polypropylene mold for the production of contact lenses, which has a thickness in the center of the cavity of about 100 pm, after which the mold is closed. The solution in the mold is irradiated with a 200W Oriel UV lamp from a distance of 18 cm for 6 seconds. The mold is then opened and a transparent contact lens is removed from the mold. This contact lens is biocompatible, which means that the lens can be worn on the eye for a long time, without having an adverse effect on the ocular environment. The lens has a modulus of 0.9 mPa and a bending elongation of 50

Oh, oh ·

Example-3

A.zalactone-modified polyvinyl alcohol is prepared as follows. 25 g of polyvinyl alcohol (Mowiol 4-98, which is commercially available from Hoechstf and has a degree of hydrolysis of 98.4% and a Mw (g/mol) of about 27,000) is dissolved in 100 g of dimethyl sulfoxide at 65°C in a 200 ml round-bottomed flask equipped with a mechanical stirrer and a nitrogen atmosphere. 0.5 g of the catalyst (1,8-diazabicyclo-[5.4.0]-undec-7-ene) is added, followed by 7.14 g (0.05.1 mol) of 2-vinyl-4,4-dimethylazalactone. The resulting mixture is then continuously stirred for 24 hours at 65°C.

The resulting modified polymer is precipitated in one liter of acetone with vigorous stirring. The precipitate is filtered off and dried. In the modified polymer about 9 mol. % ·. OH-groups of polyvinyl alcohol from the reaction'~ with azalacone. The modified polymer is . dissolved in dimethyl sulfoxide· to obtain - about 30% . . solution, after which · the photoinitiator' ..Irgacure ,2959 is added to' . obtain a 0.1% solution of photoinitiators.

About 0.6 ml of the modified crosslinkable polymer solution is placed on a quartz slide and the solution is covered with

a second quartz slide, both slides having the dimensions of a conventional microscope slide. A distance of 100 pm is maintained between the two slides by means of a spacer. The crosslinkable solution located between the two slides is then subjected to a recording process to obtain a holographic optical element, in the manner described in the first recording step of Example 1. The resulting holographic optical element has a diffraction efficiency of about 70%.

The above examples demonstrate that the polymerizable optical materials of the invention, which are selected according to the above selection criteria, produce holographic optical elements, in particular biocompatible optical elements, which can be used in various applications, including optical lenses, for example multifocal contact lenses.

Claims (4)

N O..R O K Y 1. A multifocal optical lens comprising a first optical element and a transmission bulk holographic optical element, wherein said first optical element provides a first optical power in the first focus and said holographic optical element provides a second optical power - in the second focus and the first and second focus are axially aligned. 2. Optifocal focal. the lens of claim 1. said optical lens is an ophthalmic lens and has a stabilizing mechanism. 3. A microfocal optical lens according to claim 1, wherein said holographic optical element bends up to 100% of the incoming light when it is present. - 'met. Sraggcva condition .. · 4 .... Mififocal optical lens according to. of claim 1. wherein said first optical power is selected from + 10 to -20 dioptres. - <. The multifocal optical lens of claim 4. The second optical power is a positive optical power. β V «« ft • · · ·· ··. · · · · <<, 6. The multifocal optical lens of claim 1, wherein said lens corrects myopia, hyperopia, senescence, regular and irregular astigmatism, and combinations thereof. 7. A multi-focal optical lens comprising a transmission volumetric holographic optical element having a programmed activating angle, said optical element providing a first optical power for light entering said optical element at an angle outside said activating angle. and provides a second optical power fart light entering said optical element at an angle that is the activating angle. 8. The multifocal optical lens of claim 7. characterized in that said optical lens is an ophthalmic lens and has a stabilizing mechanism. 1. . . ’ 9. The multifocal optical lens of claim 7. wherein said optical lens is a lens. . _n i a_ - ·· is contact 1Ó. The multifocal optical lens of claim 7, wherein said first optical power is selected from the range of +10 to -20 diptria. 11 _? The multifocal optical lens of claim 10. characterized in that said second optical power is a positive optical power. • · · · 12. The multifocal optical lens of claim 7 wherein said lens corrects, nearsightedness, farsightedness, age vision, &quot; regular and irregular astigmatism &quot; and combinations thereof. 13 . A method of correcting an ametropic state comprising: a) introducing a multifocal lens onto the eye, said multifocal lens comprising a first optical lens. element and transmission holographic. an optical element and said first optical element providing a first optical power in the first focus and said holographic optical element or said holographic optical element in combination with the guided 'first optical element' to provide a second optical power in the second focus, and. . (b) movement. said multifocal lens on said eye so as to be said ^; the first outbreak or - said, "second outbreak selectively" - situated at the 'point of sharpest vision on the retina of said eye. " The method of claim 13, wherein the optical lens is. and lens. a mechanism such that the lens can be moved from one position to the other. The stabilizer is to be stable 15 Dec The method of claim 13. of . 'N. characterized in that said holographic optical element bends up to 100%. of the coming light. if it is. satisfied- Bragg condition.16. 10. The method of claim 13, wherein said ametropic condition is nearsightedness, nearsightedness, age vision, regular or irregular astigmatism, or a combination thereof. ' 17. The method of claim 16 wherein said condition is age vision and said first optical power is selected from the range of +10 to -20 dioptres. ' Γ8. A method of multifocal visual correction, characterized in that it comprises ',', a) placing a multifocal lens on the eye, said multifocal lens comprising a holographic. an optical element having a programmed activating angle and said optical element providing a first optical power for light entering said optical element at an angle which is at least said; - activating angle. and providing a second optical power for the light entering said optical element at an angle that is the activating angle, and (b) moving said multifocal lens on the eye so that said first focus or said second focus is selectively situated in the eye. of the sharpest vision, on the retina. I, '·' i r. · ', P. -. : The method of claim 18. characterized in that said optical lens is an ophthalmic lens and has a stabilizing mechanism, so that said lens can be moved from one position to the other with the tablet. 20. The method of claim 18 wherein said holographic optical element bends up to 100% of the incoming light if the Bragg condition is met. . . • · 21. The method of claim 18 wherein said ametropic condition is myopia, far-sightedness, age vision, regular or irregular partigmatism, or a combination of said conditions. 2.2. The method of claim 21, wherein said ametropic state is age vision and that said first optical power is selected from the range of +10 to -20 dioptres. 23. A method for producing a multifocal optical lens for correcting ametropic states having a frontal curvature and a base curvature, comprising: (a) introducing a polymerizable optical material into an optical lens mold; and b) exposing said polymerizable. the material in said form by electromagnetic waves, said electromagnetic waves. During the polymerization of said polymerizable material, the waves form an interference scattering structure which is recorded in said lens to form. a volumetric lattice structure to form a volumetric holographic element. wherein said lattice structure is capable of bending light entering the frontal curvature of the lens and correcting said ametropic state when the lens is placed in, on or in front of the eye. . made from a pre - glymer crosslinks; or 24. A biocompatible holographic, crosslinkable or polymerizable element wherein the prepolymer polymerizes to form a non-fluid biocompatible optical element within up to 5 minutes ^; irradiation with a source of ultraviolet light, wherein the crosslinking time, or. ^51: ·· polymerization was measured by storing the prepolymer between the top and bottom slide .křemenné, 'which are spaced apart at a distance 100, and the source of the ultraviolet spectrum. 200 W medium pressure mercury lamp located 18 cm above said top silica glass. 25. The biocompatible ^x holographic element of claim 24, wherein said prepolymer is a polyvinyl alcohol derivative containing from about 0.5% to about 80%, based on the number of polyvinyl alcohol hydroxy groups, of the general formula Z. '. (and) - in which · . ' R. represents a lower alkylene group containing up to 8 carbon atoms; R ¹ represents hydrogen or. a lower alkyl group, and. R 'is an olefinically unsaturated, electron-attracting, copolymerizable group containing up to -25'carbon. educational a.toms. '' / 26th biocompatible holographic material according to claim 25, c h en characterized in that the 'R ² .znamená olefinically unsaturated acyl radical of formula ^R? -CO-, ve '. • fc fc. where R ³ is an olefinically unsaturated copolymerizable group containing from 2 to 24 carbon atoms. 27. The biocompatible holographic element of claim 26. characterized in that said olefinically unsaturated group is an ethenyl group. 2-propenyl 'J', 3-propenyl '. 2-butenyl, hexenyl, octenyl or dodecanyl. -28. A biocompatible holographic element according to claim 24, wherein said prepolymer crosslinks or the polymer is within 1 minute. . , · 29. A biocompatible holographic element according to claim 24, wherein said prepolymer crosslinks or the polymer within 30 seconds. 30. The biocompatible holographic element of claim 24, wherein said prepolymer comprises a lactalactone moiety comprising a polyvinyl alcohol, polyethyleneimine or polyvinylamine derivative. whereas . said derivative contains from about 0.5 to about 80% based on the number of hydroxyl groups in the polyvinyl alcohol or the number of imine or amine groups in the polyethyleneimine, respectively. polyvinylamine, units of formula IV or V '. ·· · * I · 4 '* 944 944 _2- ch ₂ -Ra (IV)' / R — C — R. About R. NH — C — C = CH, -ch-ch ₂ -nc = o R — C — R, (V) About R. NH — C — C = CH wherein R; and R ₂ 'independently of one another is hydrogen, C 1 -C 8 alkyl, aryl or cyclchexyl, R ₃ . represents a hydrogen atom or an alkyl group containing 1 to 8 carbon atoms and R ₄ represents. bridging group '-O- or'-NH'-. , 31. A biocompatible holographic element according to claim 24, wherein said prepolymer comprises a functionalized copolymer comprising vinyl lactam and a second vinyl monomer, wherein said vinyl lactam is a 5- to 7-membered member. The lactam of formula (VII) is represented by the formula (VII) N Rb Rc (VII) in which. ’. R. represents an alkylene bridging group containing 2 to 8 carbon atoms, R. represents a hydrogen atom, an alkyl group, an aryl group, an aralkyl group or an alkaryl group, preferably a hydrogen atom, a lower alkyl group containing up to 7 carbon atoms, an aryl group containing up to 10 carbon atoms, or aralkyl. or an alkaryl group containing up to 14 carbon atoms, and. R _c 'represents a hydrogen atom or a lower alkyl group containing up to 7 carbon atoms. 32. A biocompatible holographic element according to claim 31, wherein said vinyl lactam is N-vinyl-2-pyrrolidone, N-vinyl-2-caprolactam. N-vinyl-3-methyl-2-pyrrolidone N-vinyl-3-methyl-2-piperidone; '. N-vinyl-3-methyl-2'-caprolactam N-vinyl-4-methyl-2-pyrrolidone N-vinyl-4-methyl-2-caprolactam, N-vinyl-5-methyl-2-pyrrolidone, N-vinyl-5-methyl-1-piperidone, N-vinyl-5,5-dimethyl-2-pyrrolidone N-vinyl-3,3,5-trimethyl-2-pyrrolidone, ^r . . N-vinyl-5-methyl-5-ethyl-2-pyrrolidine, ... * · ··· · · · · · · · · N-vinyl-3,4,5-trimethyl-3-ethyl-2-pyrrolidone; N-vinyl-6-methyl-2-piperidone, N-vinyl-6-ethyl-2-piperidone, N-vinyl-3,5-dimethyl-2-piperidone, N-vinyl-4,4-dimethyl-2 -píperidon, ... N-vinyl 1-7-methyl-2-caprolactam, N-vinyl-7-ethyl-2-caprolactam, N-vinyl-3,5-dimethyl-2-caprolactam N-vinyl-4,6-dimethyl-2-caprocaltam, N-vinyl-3,5,7-trimethyl-2-caprolactam or mixtures thereof. 33. The biocompatible holographic element of claim 31, wherein said second vinyl monomer is a monomer having a vinyl group and wherein said functional group is a hydroxy group, an amino group, or a vinyl group. an amino group substituted by a lower alkyl group; carboxyl, esterified carboxyl, alkoxycarbonyl, epoxy or sulfo. 34. Biocompatible holographic element according to claim 32, characterized in that said functional vinyl monomer is selected from hydroxy-substituted. alkyl acrylates and ethoxylated acrylates and methacrylates, alkyl acrylates and methacrylates, including methacrylates, epoxy (lower epoxycycloalkyl (lower alkyl) acrylates and methacrylates, hydroxy-substituted (lower alkyl acrylamides and methacrylamides and methacrylates) alkyl) vinyl ethers, amino- or hydroxy-substituted styrenes, sodium ethylenesurfonane, sodium sulfosulfonate, 2-acrylamido-2-methylpropanesulfonic acid, acrylic acid, methacrylic acid, amino (lower alkyl) and allyl. no (lower alkyl) acrylates and methacrylates, acryloxy and methacryloxy (lower, alkyl) maleimides, and allyl alcohol. • 4 β * 4 4 ·· 4 4 « 35. A biocompatible bulk holographic element made of a crosslinkable or polymerizable prepolymer. by a process in which said prepolymer forms a volumetric holographic element when exposed to a coherent point light source and a reference light beam, wherein said prepolymer crosslinks or polymerizes to form a non-fluid biocompatible optical element for up to 5 minutes by irradiation with an ultraviolet radiation source. wherein the cross-linking or polymerization time is measured by depositing said prepolymer between a lower and upper quartz glass spaced apart by a distance of 100 µm and a source of ultraviolet radiation being a 200 watt medium pressure mercury lamp which is placed at a distance of 18 cm above said quartz glass. .- -. 36..Biocompatibilní. volumetric holographic. The element of claim 35. characterized in that it is a transmissive holographic element. 37. The biocompatible bulking element according to claim 35, wherein the bulking element is in accordance with the invention. characterized in that it is used in an application in which said holographic element is placed in or on the eye. 1 - · 38. A holographic element made of a crosslinkable or polymerizable prepolymer, said prepolymer being a liquid prepolymer and forming a holographic element when exposed to a coherent point light source and a reference light beam wherein the prepolymer crosslinks or polymerizes to form a hydrogel element at a maximum of 5 minutes of irradiation with a source of ultraviolet radiation, in which case the cross - linking time or. polymerization - measured by deposition of said prepolymer. between the top and bottom quartz glass spaced 100 µm apart, with the source / The ultraviolet light is a 200 W medium pressure mercury lamp which is located 18 cm above said top silica glass. 39. A method of manufacturing a holographic element, said method. comprising incorporating the composition. a crosslinkable prepolymer or polymerizable monomer into a mold, said prepolymer or monomer composition being a liquid composition, and use. light beams for holographic recording. wherein said liquid prepolymer or monomer is converted to a non-liquid element at most. 5 minutes. irradiation with the ultraviolet light source and the transformation time is measured by depositing said prepolymer or monomer between the lower and upper quartz glasses, the slides spaced apart from each other by a distance of 100 µm and the ultraviolet radiation source being 200. A medium pressure mercury vapor lamp located 18 cm above the top quartz glass. 40. The method of claim 39, wherein said holographic grid structure is a holographic grid structure. A volume-containing derivative of from 0.5 to about 80% of polyvinyl alcohol, The method of claim. 39, cited above. a polyvinyl alcohol prepolymer composition containing about 1% by weight. the number of hydroxy groups. of the general formula I. • · »·· ·· • · · · · · · '····» »• · · · · · · · · ··» ·· ^r .in. which means an alkylene group containing up to. 8 'carbon atoms,'. . R ¹ R ² · znamená'atom atom or a lower alkyl group and an olefinically unsaturated, electron--přitahu j ICI copolymerizable skupinu.obsahující.až .25 carbon atoms. The method of claim. 39, wherein said prepolymer composition. comprising a polyvinyl alcohol, polyethyleneimine or polyvinylamine derivative containing an azalactone moiety, said derivative comprising from about 0.5% to about 80% based on the number of hydroxyl groups in the polyvinyl alcohol or the number of imine or / amine-groups of polyethyleneimine, respectively; pblývlhy lamlnŮ7 '' ^! ýi ^, dnnbte'k '' generallibeh 'in y: c ⁼ ''' IV '''and''in ·· ··. · 4 · ch ₂ -ch ₂ Ra (IV) R — C— R. OR II ¹³ , NH-C-C = CH -ch-ch ₂ —n—. c = o AND R — C — R_ (V) About R. NH - C - C = CH in which R ₆ and R ₂ independently of one another are hydrogen, alkyl containing 1. R ₃ represents a hydrogen atom or an alkyl group containing from 1 to 8 carbon atoms and R ₄ represents a bridging group -O- or -NH-. 1 '. . 43. The method of claim 39, wherein said prepolymer composition comprises a functionalized copolymer comprising vinyl lactam and a second vinyl monomer, wherein said vinyl lactam is a 5- to 7-membered lactam of formula VII. · · <· <<<<* * * * * <<<<< "· ·· ·· ·· ·· ·· in which.. R 6 is an alkylene bridging group containing 2 to 8 carbon atoms; R. "represents an atom. hydrogen, alkyl, aryl, aralkyl or alkaryl, preferably lower alkyl of up to 7 carbon atoms, aryl of up to 10 carbon atoms or aralkyl or alkaryl of up to 14 carbon atoms, and R _c . represents a hydrogen atom or a lower alkyl group. containing up to 7 'carbon atoms. '