JPH0720766A - Hologram manufacturing method and display device - Google Patents

Abstract

PURPOSE:To provide a high-accuracy hologram while reducing the size over the entire part of the device and simplifying the device by providing an optical system with a cylindrical lens, a calculator hologram and an afocal lens system. CONSTITUTION:At least either optical system of the object optical system for generating object light and the reference light optical system for generating reference light is provided with the cylindrical lens 25, the calculator hologram 16 and the afocal lens system 20 at the time of forming the interference fringes on the recording medium and then forming the hologram thereon by making object light and reference light incident on the recording medium in the different direction. More particularly, the afocal lens system 20 is arranged behind, at least, the calculator hologram 16 with respect to coherent light for the purpose of hologram recording and has a space filter 20-2 for allowing the passage of only the prescribed diffracted light diffracted by the calculator hologram 16. The space filter 20-2 has a prescribed opening. Then, the good observation in the same visual field by spatial superposition is possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a hologram lens and a display device, for example, off-axis (of).
f-axis) type holographic lens is used as a light flux coupling element, and the image information from the image display and other image information such as natural scenery in the front field of view (behind the holographic lens) are spatially superposed to each other. It is also suitable when observing the image information in the same field of view.

[0002]

2. Description of the Related Art Display information (image information) from a display element and image information such as an external scene are within the same field of view by using an optically transparent light flux coupling element such as a multilayer reflection surface or a hologram optical element. A display device that is spatially superposed for observation is generally called a head-up display device,
It is widely used in each field.

In order to reduce the size of parts of the optical device of the head-up display device, the display device in which the light beam coupling element is provided relatively close to the observer's eye and the optical device is mounted on the helmet is a helmet. It is called a mount display device (HMD device), and is used as a display device when operating an aircraft, for entertainment such as games, or as an artificial reality (Artifici).
Various applications such as display devices for al Reality) have been proposed.

FIG. 5 is a schematic view of a main part showing a method for producing a hologram as a combiner element described in US Pat. No. 4,530,564.

In the figure, the monochromatic light from the argon laser 71 is split into two. One of the light fluxes is expanded by the microscope objective lens 72, and after the necessary spherical aberration, astigmatism, and coma aberration are corrected by the aberration correction lens system 73, it is reflected by the concave mirror 74 to become convergent light and becomes a hologram on the transparent substrate 75. It enters the recording material 76.

On the other hand, the other split light beam from the argon laser 71 is expanded by the microscope objective lens 77, and after the predetermined astigmatism and coma aberration are corrected by the aberration correction optical system 78, it is transmitted through the transparent substrate 75. Hologram recording material 7
It is incident on 6.

The above two light beams interfere with each other in the hologram recording material 76 to form a volume phase diffraction grating. The hologram recording material 76 is developed to produce a hologram. As the hologram recording material 76, dichromated gelatin or polyvinylcarbazole is used.

[0008]

In the hologram producing apparatus shown in FIG. 5, the number of components of the optical system for printing is very large,
There is a problem that it is difficult to arrange all of these optical elements at required positions.

Especially, since the cylindrical lens, the parallel plate, etc. are arranged off the optical axis, a special jig is required for the arrangement. In addition, an optical system having an extremely large diameter is required to manufacture a hologram optical element having a predetermined size.

For example, when manufacturing a hologram optical element having a diameter of 200 mm, the reflecting mirror 74 needs to have a diameter of 400 mm or more, and as a result, the printing optical system becomes very expensive. The interference fringes recorded on the hologram recording material 76 have a pitch of about 0.15 μm, and the vibration during exposure is preferably 0.01 μm or less. For this purpose, it is necessary to make a printing optical system compact and with high rigidity.
The large-sized optical system as shown in FIG. 5 has a problem that it is difficult to manufacture a highly accurate hologram.

The object of the present invention is to make it possible to manufacture a highly accurate hologram while reducing the size and simplification of the entire apparatus, and when the hologram is used as a combiner, image information from an image display and other information. (EN) A hologram manufacturing method and a display device capable of spatially superimposing image information and observing well in the same visual field.

[0012]

As a method for producing a hologram of the present invention, (1-1) object light and reference light are made incident on a recording medium from different directions to form interference fringes on the recording medium. When manufacturing a hologram, a cylindrical lens, a computer generated hologram, and an afocal lens system are provided in at least one optical system of an object light optical system that generates the object light and a reference light optical system that generates the reference light. It is characterized by being.

In particular, the afocal lens system is arranged at least after the computer generated hologram for coherent light for hologram recording, and a spatial filter that allows only a predetermined diffracted light diffracted by the computer generated hologram to pass therethrough. And the spatial filter has a predetermined opening.

(1-2) A light beam passing through an optical system including a cylindrical lens, a computer generated hologram, and an afocal lens system and a light beam of a convergent spherical wave or a divergent spherical wave are made incident on a recording medium from different directions, and A feature is that a hologram is produced by forming interference fringes on a recording medium.

In addition, in the present invention, (1-1), (1-
A plurality of element holograms produced by the method 2) are arranged on a plane to produce a hologram, and the computer generated hologram is an off-axis type hologram.

Further, according to the present invention, the afocal lens system is characterized in that the diameter of the incident light beam is enlarged from the same magnification to several times and then emitted.

As the display device of the present invention, (1-3) the light flux based on the image information from the image display device is diffracted in a predetermined direction through the hologram lens to obtain the image information and the image behind the hologram lens. When the information and the information are spatially superposed and observed in the same field of view, the hologram lens is a cylindrical lens in at least one of an object light optical system for generating an object light and a reference light optical system for generating a reference light. And a computer generated hologram and a volume phase hologram lens produced by making an interference fringe on the recording medium by making object light and reference light incident on the recording medium from different directions by using a system provided with the afocal lens system. It is characterized by being.

(1-4) The light flux based on the image information from the image display is diffracted through the hologram lens, and the image information and the image information behind the hologram lens are spatially superposed to form the same field of view. At the time of observation, the hologram lens is caused to enter a recording medium with a light beam and a light beam of a convergent spherical wave or a divergent spherical wave through an optical system including a cylindrical lens, a computer generated hologram, and an afocal lens system, A volume phase hologram lens manufactured by forming interference fringes on the recording medium.

[0019]

Embodiment 1 FIG. 1A is a schematic view of the essential portions of Embodiment 1 of the present invention. In this embodiment, an optical system (printing optical system) for manufacturing a hologram lens is shown.

In FIG. 1A, the laser light 2 having a wavelength of 514.5 nm from the argon ion laser 1 is divided into two light beams by the half mirror 3. One of these optical paths is an object light optical system that generates object light, and the other optical path is a reference light optical system that generates reference light. The light beam 2a reflected by the half mirror 3 is reflected by the mirror 5, the light beam diameter is enlarged by the microscope objective lens 6, and thereafter, the collimator lens 7 makes a parallel light beam 8 and enters the converging lens 9.
The light flux converged by the converging lens 9 is converted into a convergent spherical wave 10 having a predetermined radius of curvature that converges on the point F, and is incident on the hologram recording material 12 coated or attached on the transparent substrate 11 such as glass.

On the other hand, the light beam 2b that has passed through the half mirror 3 is reflected by the reflecting mirror 4, the light beam diameter is enlarged by the microscope objective lens 13, and then the collimator lens 14 collimates the parallel light beam 15.
A computer generated hologram (hereinafter referred to as "CG
H ”) 16 is incident at a predetermined incident angle.

The light beam incident on the CGH 16 is diffracted.
Of these, first-order diffracted light (solid line) 17, zero-order diffracted light (broken line)
19 and the −1st-order diffracted light (dashed line) 18 respectively enter the afocal lens system 20.

Of the diffracted light, the 0th-order transmitted light 1 is transmitted by the lens 20-1 constituting the afocal lens system 20.
The 9th and −1st-order diffracted light 18 are converted into light beams 23 and 22, respectively, and are shielded by the spatial filter 20-2 having a predetermined aperture arranged near the focal point of the lens 20-1. Only the light beam 21 passes. This light flux 21 is expanded again by the lens 20-3 to become a light flux 24, which is incident on the cylindrical lens 25 and is converted into a light flux 26 having a wavefront mainly given astigmatism, and is then converted into the hologram recording material 12 provided on the substrate 11. Incident.

Afocal lens system 2 used in this embodiment
Although 0 is set so as to be the output light flux 24 that is equal to the incident light flux 17, it is not always necessary to convert the light flux to the same magnification, and the output light flux diameter may be converted to several times. In such a case, there is an effect that the size of the CGH 16 can be reduced and the production of CGH described later can be facilitated.

In this embodiment, the aberrations imparted by the CGH 16 are slight coma and astigmatism. The spot of the + 1st order diffracted light 17 by the lens 20-1 is not necessarily circular and has a predetermined shape. The shape of the aperture of the spatial filter 20-2 used in this embodiment is set so as to substantially match this spot shape. In the present embodiment, the afocal lens system 20 is illustrated as being composed of two lenses 20-1 and 20-3 for the sake of simplicity, but the lens element is not limited to this. Instead, various configurations can be used.

FIG. 1B is an explanatory diagram showing the aperture shape of the spatial filter 20-2 used in this embodiment. In the figure,
The shaded area is the light shielding area.

The two light beams 10 and 26 incident from both sides of the hologram recording material 12 interfere with each other, and the interference fringes are recorded on the hologram recording material 12. The hologram recording material 12 undergoes a known development process to produce a hologram lens.

As the CGH used in this embodiment, optically exposed ones, electron beam exposed (EB exposure) or the like can be used.

FIG. 2 is a schematic view of the essential portions of Embodiment 2 of the present invention.

The present embodiment is different from the first embodiment shown in FIG. 1 in that the afocal lens system 20 and the cylindrical lens 25 are interchanged in optical arrangement, and other configurations are the same. .

In this embodiment, the 0th-order transmitted light (broken line) 19, the + 1st-order diffracted light (solid line) 17, and the -1st-order diffracted light (dashed-dotted line) 18 diffracted by the CGH 16 are respectively made by the cylindrical lens 25 to a large non- The light is incident on the afocal lens system 20 after being given point aberration. Of these diffracted lights, only the + 1st order diffracted light 17 becomes the light beam 21 and passes through the spatial filter 20-2, and the other diffracted lights 18 and 19 become the light beams 22 and 23 and are shielded by the spatial filter 20-2. . Spatial filter 20
The light flux 21 of the + 1st-order diffracted light 17 that has passed through −2 is the lens 2
The light beam is expanded again at 0-3 to form a light beam 26, which is incident on the hologram recording material 12 provided on the substrate 11 as a light beam having a wavefront having a predetermined aberration.

Compared to the first embodiment, C
The distance between the GH 16 and the spatial filter 20-2 increases, and the luminous fluxes 21 and 21 condensed by the lens 20-1.
Since 2 and 23 are spatially separated, they have the effect of separating spots and facilitating filtering of a predetermined light flux.

FIG. 3 is a schematic view of the essential portions of Embodiment 3 of the present invention. The present embodiment shows a case where a hologram lens array including a plurality of element holograms divided into a plurality of regions is manufactured. In the figure, for simplicity, two element holograms 1
Although it is shown that it is composed of 2-1 and 12-2, there may be any number.

FIG. 3A shows an optical path in the vicinity of the hologram recording material 12-1 when the first element hologram 12-1 is recorded using the optical system shown in Example 1 of FIG.

In the figure, the monochromatic light from the laser light source is focused on the point F as described in the first embodiment.
The hologram recording material 1 on the substrate 11 includes the H 16 and the wavefront 26 that is aberrated by the cylindrical lens 25.
The light is incident on 2-1 from opposite sides. Then, the first interference fringes are recorded on the hologram recording material 12-1.

Next, using the same optical system as in Example 1,
Second interference fringes are recorded on the hologram recording material 12-2. FIG. 3B is a schematic diagram of the vicinity of the hologram recording material 12-2 of the optical system for recording the second interference fringes at this time.

The second interference fringes are the spherical wave 10a diverging from the point F, the CGH 16 and the cylindrical lens 25.
The two light fluxes of the wavefront 26a, which are given the aberration by the above, are made incident on the hologram recording material 12-2 from opposite sides to record interference fringes on the hologram recording material 12-2.

In the present embodiment, when each element hologram is exposed, it is shielded by using a dry plate holder or the like or by using an appropriate mask or the like so that unnecessary light does not enter other than the exposed portion of the hologram recording material. Means are provided.

In the present embodiment, each element hologram 12-
1 and 12-2 show the case where the holograms are connected so that the edges thereof are adjacent to each other, the optical characteristics of the element holograms in this embodiment have the same function of condensing the reproduction light to the point F. Therefore, even if there is some overlap area between each element hologram, it does not matter at all.

In this case, the phase of each element hologram does not necessarily have to be the same.

The hologram obtained in the above-mentioned embodiment can improve many defects as compared with the case where the conventional hologram manufacturing method is used.

The optical system for hologram production of this embodiment is greatly simplified as compared with the conventional optical system shown in FIG.
Moreover, ready-made products can be used. As shown in FIG. 1, the optical system that spreads the laser light 2 as a spherical wave through the microscope objective lenses 6 and 13 and collimates it by the collimator lenses 7 and 14 is rotationally symmetric with respect to the optical axis and can be easily centered. Moreover, it is possible to use inexpensive products that are used in large quantities in other fields for each lens.

If a microscope objective lens for infinity correction is used for the microscope objective lenses 6 and 13, there is almost no aberration, and as the collimator lenses 7 and 14, an objective lens of a telescope or a telephoto lens for photography can be used.

The minimum diameter of the lens used here is sufficient, and it suffices to cover the required area of the element hologram. Furthermore, in the manufacturing method shown in FIG.
Since a printing area required for one exposure may be small, a significantly inexpensive optical system can be used.

In addition, the CGH 16 is the most expensive optical system for hologram production in this embodiment, but the afocal lens system 20 used in this embodiment has a magnifying power of several times instead of 1 ×. CGH16
It is also possible to reduce the size of the hologram recording optical system, and in this case, the hologram recording optical system can be constructed at a lower cost.

Further, as a secondary advantage, if the exposure time required for printing is a small area, the product yield can be improved because the product can be completed in a shorter time. In the present invention, since the pitch of the diffraction grating used in the direction perpendicular to the grating is about 0.15 μm, even a slight vibration at the time of exposure causes a drastic decrease in diffraction efficiency. The benefits of shortening are large.

FIG. 4 is a schematic view of the essential portions of Embodiment 4 of the present invention. In this embodiment, an image observation apparatus using the hologram lens 12 manufactured by the method described in FIG. 3 as a light beam coupling element is shown.

In this embodiment, a light source 30 such as a halogen lamp is used.
The light flux emitted from the lamp 8 is converted into substantially parallel light by the lamp house 307 having an appropriate shape, and illuminates the liquid crystal display element 306 as the image information of the image display. Liquid crystal display element 3
The light flux 324 emitted from the image information of the point F1 on the display surface 305 of 06 is incident on the hologram lens array 303 formed on the transparent substrate 302 such as glass or plastic.

The hologram lens array 303 uses the light beam 3
The element hologram 331 satisfying the Bragg condition is provided only for 24, and the light beam 324 is reflected and diffracted only by the element hologram 331 and enters the observer's pupil 301. At this time, the element hologram 331 has a lens function of converting the light beam 324 into a slight divergent light beam. The observer observes the image information at the point F1 on the display surface 305 as a virtual image based on the light beam 304a diverging from the point F1a in front of the hologram lens array 303.

For the same reason, the luminous fluxes emitted from the image information at the points F2 and F3 on the display surface 305 of the liquid crystal display element 306 are reflected and diffracted toward the observer's pupil 301 only by the element holograms 332 and 333, respectively. . Thereby, the image information of the points F2 and F3 is observed as a virtual image based on the light flux diverging from the points F2a and F3a in front of the hologram lens array 303.

As described above, each point on the display surface 305 of the liquid crystal display element 306 corresponds to each element hologram 331, 332, 3
It is reflected and diffracted at 33 to form a virtual image plane 309.

In the present invention, even if a white light source is used, since the element hologram has wavelength selectivity (wavelength dependence of diffraction efficiency), the central wavelength λ0 satisfying the Bragg condition is satisfied.
Has a peak of diffraction efficiency. At this time, when the full width at half maximum is set to 2Δλ, the element hologram causes the reflection diffraction action only for the light flux of λ0 −Δλ to λ0 + Δλ in the incident white light. Therefore, in this embodiment, a halogen lamp is used as the light source.

Further, as a matter of course, it is possible to use an interference filter which transmits only a light beam of a necessary wavelength among the light beams from the halogen lamp. In addition, in this embodiment, each element hologram 331, 332, 333 has areas 361, 362, 363 whose aberrations are well corrected, and the points on the virtual image plane 9 formed by the areas 361a, 362a, 363a are It can be observed as a point image with almost no aberration.

As described above, according to the first to fourth embodiments, it is possible to manufacture a hologram with a simple structure, and it is only necessary to change the computer generated hologram (CGH) with respect to the specification change at the time of reproducing the hologram (in use). It is possible to deal with the problem, and further, by dividing and exposing the hologram, it is possible to remove the adverse effect due to vibration or the like during the exposure. Further, a high-quality hologram can be manufactured by surely cutting unnecessary high-order diffracted light by CGH during hologram recording.

[0055]

According to the present invention, by setting the optical system as described above, it is possible to manufacture a highly accurate hologram while reducing the size and simplification of the entire apparatus, and use the hologram as a combiner. In this case, it is possible to achieve a hologram manufacturing method and a display device capable of spatially superimposing the image information from the image display and other image information and observing well in the same visual field.

In the present invention, an aberration is added to the exposure wavefront because the afocal lens system is used as compared with the hologram creating optical system using the ordinary CGH.
The CGH fine structure is set and corrected so that a wavefront that cancels the additional aberration is generated at the time of GH design. As a result, an inexpensive afocal lens system can be used.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of a first embodiment of the present invention.

FIG. 2 is a schematic view of the essential portions of Embodiment 2 of the present invention.

FIG. 3 is a schematic view of a main part of a method of manufacturing a hologram lens of the present invention.

FIG. 4 is a schematic view of a display device using the hologram lens of the present invention.

FIG. 5 is a schematic view of a main part of a conventional method for producing a hologram lens.

[Description of Reference Signs] 1 laser light source 11 substrate 12 hologram recording material 16 computer generated hologram (CGH) 20 afocal lens system 20-1, 20-3 lens 20-2 spatial filter 25 cylindrical lens 301 pupil 303 hologram lens 306 liquid crystal display element 307 Lamphouse 308 Light source 309 Virtual image plane 331, 332, 333 Element hologram

Claims (9)

[Claims] 1. An object light optical system for generating the object light when a hologram is produced by making the object light and the reference light incident on the recording medium from different directions to form interference fringes on the recording medium. A method for producing a hologram, characterized in that a cylindrical lens, a computer generated hologram, and an afocal lens system are provided in at least one optical system of a reference light optical system for generating reference light. 2. The spatial filter, wherein the afocal lens system is disposed at least after the computer generated hologram for coherent light for hologram recording, and passes only a predetermined diffracted light diffracted by the computer generated hologram. The method for producing a hologram according to claim 1, further comprising: 3. The method for producing a hologram according to claim 2, wherein the spatial filter has a predetermined opening. 4. A light beam passing through an optical system including a cylindrical lens, a computer generated hologram, and an afocal lens system and a light beam of a convergent spherical wave or a divergent spherical wave are incident on the recording medium from different directions, and the recording medium is irradiated with the light. A method of producing a hologram, characterized in that interference fringes are formed to produce a hologram. 5. A method for producing a hologram, wherein a plurality of element holograms produced by the method according to claim 3 or 4 are arranged on a plane to produce a hologram. 6. The computer generated hologram is off-axis.
The method for producing a hologram according to claim 3, wherein the hologram is an s-type hologram. 7. A light flux based on image information from an image display is diffracted through a hologram lens in a predetermined direction to spatially superimpose the image information and the image information behind the hologram lens in the same field of view. At the time of observation, the hologram lens is provided with a cylindrical lens, a computer generated hologram, and an afocal lens system in at least one optical system of an object light optical system for generating an object light and a reference light optical system for generating a reference light. A display device characterized by being a volume phase hologram lens produced by making object light and reference light incident on a recording medium from different directions by using the above system to form interference fringes on the recording medium. 8. A light beam based on image information from an image display is diffracted through a hologram lens, and the image information and the image information behind the hologram lens are spatially overlapped and observed in the same visual field. At this time, the hologram lens makes a light beam passing through an optical system including a cylindrical lens, a computer generated hologram, and an afocal lens system and a light beam of a convergent spherical wave or a divergent spherical wave enter a recording medium from different directions, and the recording medium A display device, which is a volume phase hologram lens manufactured by forming interference fringes on the surface. 9. The hologram manufacturing method and display device according to claim 1, wherein the afocal lens system enlarges the incident light beam diameter from the same magnification to several times and emits it.