Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/0025—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for optical correction, e.g. distorsion, aberration
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/0075—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 with means for altering, e.g. increasing, the depth of field or depth of focus
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B15/00—Optical objectives with means for varying the magnification
  • G02B15/14—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective
  • G02B15/16—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective with interdependent non-linearly related movements between one lens or lens group, and another lens or lens group
  • G02B15/163—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective with interdependent non-linearly related movements between one lens or lens group, and another lens or lens group having a first movable lens or lens group and a second movable lens or lens group, both in front of a fixed lens or lens group
  • G02B15/167—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective with interdependent non-linearly related movements between one lens or lens group, and another lens or lens group having a first movable lens or lens group and a second movable lens or lens group, both in front of a fixed lens or lens group having an additional fixed front lens or group of lenses
  • G02B15/17—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective with interdependent non-linearly related movements between one lens or lens group, and another lens or lens group having a first movable lens or lens group and a second movable lens or lens group, both in front of a fixed lens or lens group having an additional fixed front lens or group of lenses arranged +--

Definitions

• the present invention relates to a wavefront manipulator having at least a first optical component and a second optical component, which are arranged one behind the other along an optical axis.
• the invention relates to a use of the wavefront manipulator and an optical device with a wavefront manipulator.
• optical elements having at least one first optical component and a second optical component, which are arranged one behind the other along an optical axis, each have a refractive free-form surface and are displaceable relative to one another relative to the optical axis.
• the refractive power of an optical element composed of the two components can be varied.
• Such optical elements are therefore also called Alvarez elements or Variolinsen.
• a variable refractive power corresponds to a variable focal position, which can be described by a change in the parabolic component of the wavefront of a beam bundle incident parallel to the axis. In this sense, a vario lens can be considered as a special wavefront manipulator.
• Variolenses which may be provided according to the teaching of US 3,305,294 are suitable for numerous applications. Examples of this are performing rapid Z-scans of a focus position for acquiring three-dimensional image information, the three-dimensional image stabilization, as described for example in DE 10 2011 054 087 or the compensation of a defocusing, for example in the field of microscopy by varying a cover glass thickness or by Variation of a refractive index can occur.
• zoom lenses can be used to realize a zoom functionality, such as photo or film camera lenses, especially flat-mounted Vario lenses in compact cameras and mobile phones.
• an advantageous wavefront manipulator with at least a first optical component and a second optical component, which are arranged along an optical axis in a row and perpendicular to the optical Axle can be moved relative to each other, to provide. It is a second object of the present invention to provide an advantageous optical device.
• a third object of the present invention is to provide an advantageous use for the wavefront manipulator according to the invention.
• the first object is achieved by a wavefront manipulator according to claim 1, the second object by an optical device according to claim 16 and the third object by use of a wavefront manipulator according to claim 17.
• the dependent claims contain advantageous embodiments of the invention.
• An inventive wavefront manipulator comprises at least a first optical component and a second optical component, which are arranged one behind the other along an optical axis.
• the first optical component and the second optical component are each arranged to be movable relative to one another in a direction of movement perpendicular to the optical axis.
• the first optical component and the second optical component each have at least one refractive free-form surface.
• the optical components can be arranged so that free-form surfaces of adjacent optical components face each other, or so that the freeform surfaces are facing away from each other.
• Such an optical element has, however, without further measures on the adjustment of the strength of the power-dependent, variable color error. These manifest themselves when using the optical element in an optical system, depending on its arrangement in the beam path either predominantly as longitudinal chromatic aberration or as lateral chromatic aberrations, also called chromatic magnification errors. Thus, when pupil-like arrangement occur mainly longitudinal chromatic aberration, near the field Arrangement predominantly lateral chromatic aberration. In other arrangements, other aberrations such as coma or astigmatism may also be wavelength dependent, such that, for example, chromatic variations of astigmatism or chromatic coma may result as aberrations.
• an immersion medium contacting the two components is therefore located in the wavefront manipulator according to the invention between the first optical component and the second optical component.
• Suitable immersion medium are, in particular, liquids, for example ultrapure water, salt solutions, immersion oils, etc., and elastic optics. Since only a lateral movement of the first optical component and the second optical component takes place, the wavefront manipulator with immersion medium can have a flat construction, ie a small extent perpendicular to the lateral direction of movement.
• a variably adjustable wavefront manipulation can be achieved, the effect of which is independent of the wavelength over an extended wavelength range, so that the wavefront manipulator according to the invention can be used as an achromatic wavefront manipulator.
• the wavefront manipulator according to the invention therefore, the color errors described above, in particular the longitudinal chromatic aberrations, can be largely avoided when varying the refractive power.
• he provides a suitable solution to the problem of compensation for thickness and index fluctuations in microscopy with high-aperture objectives, as described in the introduction.
• the wavefront manipulator according to the invention has a broad field of application in the correction of primary and secondary chromatic aberrations, which goes beyond the mere use as an achromatic vario lens.
• it can achromatically provide a variable parabolic phase effect, ie a variable optical power.
• It allows a targeted influence on higher order of errors of the wavefront, such as for the targeted influence of spherical aberration, coma or astigmatism.
• the freeform surface profile to be used for this purpose is given in the direction parallel to the displacement direction by the parent function of the pupil function, ie the function which describes the pupil dependence of the wavefront error, and in the direction perpendicular thereto by a function proportional to the pupil function.
• An application for the wavefront manipulator is also conceivable, for example, where a Vario basic optics, which may consist of conventional lens groups displaceable relative to one another along the optical axis, has variable values of the image aberration over an adjustment range. This variable aberration can then be selectively compensated by a wavefront manipulator according to the invention over the entire adjustment range. It is therefore possible, for example, to use the wavefront manipulator as compensating element in a photographic zoom lens in which then a compensation of the zooming dependent compensation of the occurring and by conventional means not correctable aberrations takes place.
• the first optical component and the second optical component are each movable in a direction of movement perpendicular to the optical axis by a distance of a maximum of 50 pm.
• the maximum possible distance over which the components can be moved without inducing disturbing stresses depends in particular on the shear modulus of the opto-cuttings used. It is particularly advantageous if the first optical component and the second optical component can each be moved by a distance of a maximum of 20 ⁇ m, in particular of a maximum of 10 ⁇ m, since this increases the number of usable optical elements.
• the two wavelengths ⁇ and ⁇ 2 are the wavelengths to which the two Abbe numbers refer as secondary wavelengths, if, as usual, defined:
• An achromatic wavefront manipulator ie a wavefront manipulator, with which a wavefront manipulation can be brought about essentially without color aberration, can be obtained, for example, if the first optical component and the second optical component consist of the same material and the material of the optical components and the immersion medium fulfill the following condition:
• Ni and vi denote the refractive index and the Abbe number respectively of the material of the optical components
• n 2 and v 2 denote the refractive index. index or the Abbe number of the immersion medium.
• the described achromatic wavefront manipulator can be embodied, in particular, as an achromatic lens with variable refractive power, that is to say as an achromatic variolynx, if the free-form surfaces of the optical elements are designed to influence the parabolic component of the wavefront. If a particular wavefront error, which can be clearly described by its dependency on the pupil coordinates or alternatively by reference to the Zernike order, is to be influenced by the wavefront manipulator, the surface profile in the direction parallel to the sliding direction of the elements is proportional to the parent function of this pupil function , and to choose perpendicularly proportional to the pupil function itself.
• any wavefront manipulation at the fundamental wavelength can be brought about without generating appreciable chromatic aberrations.
• the degree to which color errors are avoided depends on how large the limits to be met in the above inequality are.
• Analogous to the condition for achieving achromatic (more precisely: dichromatic) correction of the wavefront manipulator, a corresponding condition for apochromatic (more precisely: trichromatic) correction and an explicit condition for the disappearance of the secondary spectrum can be established.
• a color error especially the longitudinal chromatic aberration, but not only targeted Zero to achieve achromatization, but the wavefront manipulator can be formed, for example, with a different choice of optical media, that a defined color error for a Rand or Mauwellendorfn the transmitted wavelength range is generated.
• a defined refractive power change that is to say a defined defocusing, is generally brought about at the same time for a mean wavelength of the transmitted wavelength range. In some applications this can be tolerated.
• the first optical component and the second optical component consist of the same material and the material of the optical components and the immersion medium fulfill the following conditions:
• ni and v- ⁇ denote the refractive index and the Abbe number of the material of the optical components and n2 and V2 the refractive index and Abbe's number of the immersion medium.
• One Wavefront manipulator which satisfies the aforementioned inequalities, represents a wavefront manipulator for selectively influencing the chromatic variation of the wavefront intervention.
• the material of the optical components can be, for example, glass, crystalline material or plastic.
• An example of an immersion medium is an organic hydrocarbon, water or an aqueous solution.
• the material of the optical components is plastic, the immersion medium is an alkali-ion-doped aqueous solution, or a saline solution.
• the wavefront manipulator according to the invention can be used not only in the visible spectral range but also in the UV spectral range.
• the material of the optical components for example, quartz glass or a crystalline material may be selected.
• highly pure water is considered as immersion medium.
• the structure of the refractive free-form surfaces of the optical components comprises a superposition of at least two structural profiles
• different wavefront manipulations in any fixed predetermined relationship can be carried out simultaneously.
• the actual free-form surface of the optical components may be formed by an overlay of a free-form surface for changing the refractive power and a free-form surface for changing the spherical aberration.
• a corresponding variola varies with the displacement of the optical components against each other a refractive power and at the same time changes a spherical aberration, both changes are proportional to each other with an arbitrary but firmly vorzusphaglenden proportionality factor.
• both the front side and the rear side of an optical component are provided with a refractive free-form surface.
• This development makes it possible to provide wavefront manipulators with profile depths of the freeform surfaces smaller than 30 ⁇ m, in particular smaller than 10 m.
• the refractive free-form surface of the first component may be assigned a first diffractive structure and the refractive free-form surface of the second component a second diffractive structure.
• the associated diffractive structures can then be used to influence a wavelength-dependent effect of the respective refractive free-form surface.
• a suitably chosen immersion medium it is then possible to bring about a far-reaching independence of the diffraction efficiency of the diffractive structure from the wavelength, so that a so-called efficiency Achromatized diffractive optical element (EA-DOE) receives.
• EA-DOE efficiency Achromatized diffractive optical element
• the independence of the diffraction efficiency from the wavelength is obtained, in particular, when the first optical component and the second optical component consist of the same material, the material of the optical components and of the immersion medium have refractive indices whose difference is a linear function of the wavelength, and the material / Medium having the lower refractive index has a higher dispersion than the material / medium having the higher refractive index.
• the shape of a refractive free-form surface can be described in each case by a polynomial winding which has development coefficients that are different from zero in finitely many specific polynomial orders.
• the diffractive structure associated with a refractive free-form surface is then described by a polynomial winding which has non-zero development coefficients in the same polynomial orders as the polynomial winding of the refractive free-form surface.
• Those development coefficients of a polynomial winding describing a refractive free-form surface and the polynomial winding describing the associated diffractive structure, which are each assigned the same polynomial order, are in a fixed functional relationship to one another.
• the development coefficients respectively associated with the same polynomial order of a polynomial winding describing a refractive free-form surface and the polynomial winding describing the associated diffractive structure may be in a linear functional relationship in particular.
• the functional relationship may in particular depend on the material used in the respective optical component, ie on its dispersion.
• an identical functional relationship can be present for all polynomial orders having coefficients other than zero.
• the polynomials of the first and second polynomial windings may each be appended by two variables representing different directions perpendicular to the optical axis of the optical element.
• the two directions can be perpendicular to one another, wherein the one direction corresponds to the direction of movement of the optical components and wherein the polynomial winding describing a refractive free-form surface and the polynomial winding describing the associated diffractive structure each have only odd polynomial orders in those variables which the direction of movement of the optical components represents.
• the polynomial winding describing a refractive free-form surface and the polynomial winding describing the associated diffractive structure then each need only have straight polynomial orders in that variable which represents the direction perpendicular to the direction of movement of the optical components.
• an optical device is provided.
• the optical device according to the invention can be, for example, an optical observation device such as a microscope, in particular a surgical microscope, a telescope, a camera, etc. But it can also be another optical device such as, for example, an optical measuring device. It is equipped with at least one wavefront manipulator according to the invention. Therefore, in the optical device of the present invention, the effects and advantages described with respect to the optical element of the present invention can be obtained.
• a use of at least one wavefront manipulator according to the invention is provided.
• at least one wavefront manipulator according to the invention serves to bring about one or more of the following corrections or reductions: dichromatic correction, trichromatic correction, reduction of the secondary spectrum, reduction of the tertiary spectrum.
• a trichromatic correction can, for example, be brought about by using at least two wavefront manipulators according to the invention.
• the additional degrees of freedom gained by the additional diffractive structure can be used for trichromatic correction, because the diffractive structure according to the Sweatt model corresponds to a lens made of a material with an equivalent (negative) Abbe number.
• a wavefront manipulator comprising two moving free-form elements with an immersion medium located therebetween and a diffractive structure on the free-form elements has three independently adjustable refractive powers with which the trichromatic condition can be fulfilled.
• the condition for the disappearance of the secondary or tertiary spectrum requires at least one medium whose partial dispersion deviates from the normal straight line.
• This condition can also theoretically and practically meet with a variolysis invention or a wavefront manipulator according to the invention, since the known immersion oils, such as, for example, the Immersol 518N, bring about an abnormal partial dispersion for chemical reasons.
• a variola invention according to the invention whose free-form elements are formed from a standard glass (glass whose dispersion behavior follows the normal straight line), between which a conventional immersion oil is located, one can actually meet the condition for the disappearance of the secondary spectrum without great difficulty.
• a wavefront manipulator in a further use of a wavefront manipulator according to the invention, this can be used to bring about a position-dependent correction of at least one wavefront error in a zoom lens.
• the wavefront manipulator can be arranged in particular in the region of an (approximately) collimated beam path in the zoom lens and can be laterally deflected depending on the position of the zoom lens in such a way that it produces a wavefront error (eg, a longitudinal chromatic aberration, a spherical aberration, etc.) of the zoom lens.
• Figure 1 shows a first embodiment of a wavefront manipulator according to the invention in a schematic representation.
• Figure 2 shows an alternative embodiment of the wavefront manipulator according to the invention in a schematic representation.
• FIGS 3 and 4 show a festbrennweitige optics and the occurring
• FIGS. 5 to 9 show an optic with a wavefront manipulator in various positions.
• FIGS. 10 to 14 show those shown in FIGS. 5 to 9
• FIGS. 15 to 19 show those shown in FIGS. 5 to 9
• FIG. 20 shows a third exemplary embodiment of the wavefront manipulator according to the invention in a schematic representation. shows a third embodiment of the wavefront manipulator according to the invention in a schematic representation.
• cj denotes the refractive power of the jth lens and ( ⁇ , Xi) the associated Abbe number of the medium from which the lens is formed with reference to the auxiliary wavelengths ⁇ -1, ⁇ , defined by: If at the same time a predetermined system breaking force O tot is to be achieved, the following additional condition must also be fulfilled:
• the above reasoning can be directly transmitted analogously.
• the dichroism condition remains exactly and the second equation (constant power) is replaced by an analogue equalization setting a requirement (constraint) for the overall system effect on the desired wavefront error (eg, spherical aberration).
• the size is defined as the so-called partial dispersion coefficient P of a medium at the reference wavelength ⁇ and the spurious wavelengths ⁇ and ⁇ 2
• a wavefront manipulator according to the invention in generalization of the above conditions, the wavefront effect of a wavefront manipulator according to the invention at exactly three wavelengths ⁇ , ⁇ and ⁇ 2 are exactly the same
• a first exemplary embodiment of a wavefront manipulator according to the invention is shown in FIG.
• the wavefront manipulator comprises two optical components 1, 3, which are arranged one behind the other along an optical axis OA and are arranged laterally, ie perpendicular to the optical axis OA, displaceable relative to one another, as indicated in the figure by the arrows in -y and + y direction is.
• each of the two optical components 1, 3 has a refractive free-form surface 5, 7 on one side and a plane surface 9, 11 on the side remote from the free-form surface.
• the optical components 1, 3 are arranged relative to one another such that their free-form surfaces 5, 7 lie opposite one another.
• the free-form surfaces 5, 7 behave in a zero position exactly complementary to each other, so that the two optical components 1, 3 are equivalent in a zero position of a plane-parallel plate.
• an immersion medium 13 which in the exemplary embodiment shown in FIG. 1 is a liquid such as ultrapure water, a salt solution, an immersion oil, etc.
• the peripheral surface of the wavefront manipulator is provided with an elastic sleeve 15, which prevents leakage of the liquid immersion medium 13 and also in the lateral movement of the optical components 1, 3 relative to each other keeps tight.
• the sleeve 15 may, for example, be formed by a plastic film. Instead of a cuff of elastic material but also another liquid-tight seal can be used, for example. In the form of a bellows construction. Since the lateral movement of the optical components 1, 3 is in many cases only fractions of a millimeter, a variety of common liquid-tight seals are basically applicable. For example.
• the surfaces to be wetted by the immersion liquid with an adhesive coating which holds a thin immersion film between the free-form surfaces by adhesive forces and thus prevents leakage of the immersion liquid.
• the optical components 1, 3 themselves may, for example, consist of glass, of plastic or of crystalline material. The choice of material may depend in particular on the intended use of the wavefront manipulator. If this is to be used in the optical spectral range, the choice will usually fall on glass or plastic. On the other hand, if it is to be used in the ultraviolet spectral range, the optical components 1, 3 will typically consist of quartz glass or a crystalline material, such as calcium fluoride or barium fluoride. As immersion liquid, for example, ultrapure water is considered in the ultraviolet spectral range.
• FIG. 2 A second embodiment of the wavefront manipulator according to the invention is shown in FIG. Elements which do not differ from the wavefront manipulator of the first embodiment are designated in FIG. 2 with the same reference number as in FIG. 1 and will not be explained again in order to avoid repetitions.
• the wavefront manipulator of the second embodiment differs from that of the first embodiment in that the immersion medium is formed by an elastic optic material 17 instead of a liquid. On an elastic sleeve, as it is present in the first embodiment, is therefore omitted in the second embodiment.
• wavefront manipulator of the second embodiment is advantageous if the two optical components 1, 3 are each limited in their movement perpendicular to the optical axis to a maximum displacement of 50 pm in order to avoid disturbing voltages in the optocouple 17.
• the maximum possible distance over which the optical components can be moved without inducing disturbing voltages depends in particular on the shear modulus of the opto-cuttings used.
• the wavefront manipulator in the simplest embodiment has exactly two optical components 1, 3 which can be displaced laterally, ie transversely to the optical system axis OA (compare FIGS. 1 and 2, in which the one optical component 3 in + y is shifted, the other optical component 1 in -y direction, both in opposite directions by equal amounts).
• the free-form surface may preferably be described by a polynomial having only straight powers of x in a direction orthogonal to the direction of movement of the optical components 1, 3 and in a direction y parallel to the direction of movement has only odd powers of y.
• the free-form surface z (x, y) can first generally, for example, by a polynomial winding of the form oo
• x, y and z denote the three Cartesian coordinates of a point lying on the surface in the local area-related coordinate system.
• the coordinates x and y are to be used as dimensionless measures in so-called lens units in the formula. Lens units here means that all lengths are first given as dimensionless numbers and later interpreted to be consistently multiplied by the same unit of measure (nm, pm, mm, m).
• the background is that the geometric optics is scale-invariant, and in contrast to the wave optics does not have a natural length unit.
• a pure defocusing effect can be effected according to the teaching of Alvarez, if the free-form surface of the optical components 1, 3 can be described by the following polynomial of 3rd order:
• the lateral displacement of the optical components 1, 3 takes place along the y-axis, which is thereby defined. If the displacement is to take place along the x-axis, the role of x and y must be changed accordingly in the above equation.
• the parameter K virtually scales the profile depth and in this way determines the achievable refractive power change per unit of the lateral displacement path s.
• s 4 K - s (n - ⁇ ) (4)
• K is the scaling factor of the tread depth
• n is the refractive index of the material from which the lens is formed at the respective wavelength.
• a term proportional to y can also be added, the optical effect of which on the two free-form surfaces then almost canceling out, but minimizing the center thickness of the element.
• a pure tilting term on the free-form surfaces is optically ineffective in a first approximation and therefore does not cause any color aberrations in particular.
• the free-form surfaces can have additional terms of higher order for influencing individual image defects.
• the structure profiles may be freely superimposed, i. a structure for changing the refractive power and a structure for changing the spherical aberration may be superimposed in a free-form surface 5, 7, so that a corresponding wavelength manipulator upon displacement of the optical components 1, 3 against each other varies a refractive power and simultaneously changes a spherical aberration, both Changes are proportional to each other with an arbitrarily but firmly preselected proportionality factor.
• both sides of the moving optical components 1, 3 could have an active mold according to the forms described above.
• a symmetrical division of the surface profile according to the above formula on the front and rear surface of a component could cause the tread depths on each surface to remain sufficiently low, such that, for example, a photolithographic fabrication of the elements, typically only maximum tread depths in the range ⁇ 10-30 allows ⁇ ⁇ ⁇ , is facilitated.
• the adaptation of the immersion medium 13, 17 to the material of the optical components 1, 3 will be described below with reference to two concrete examples.
• the condition for the adaptation of the immersion medium 13, 17 to the material of the optical components 1, 3 in the wavefront manipulator can be derived as follows:
• the condition for achromaticity for two closely spaced lenses is generally:
• vi and V2 denote the Abbe number of the material of the free-form elements 1, 3 or the Abbe number of the immersion medium.
• a parameter range for a variolysis according to the invention can be characterized approximately by the following conditions:
• An achromatic wavefront manipulator which is intended to influence a specific Zernike term instead of defocusing, also has to fulfill the same achromatization condition (7) or (8a) to (8c).
• Fundamental wavelength is generated by the free-form profile function z (x, y) is designed in the direction of movement of the elements to each other proportional to the parent function of AW (x, y) and perpendicular to the direction of movement proportional to the function AW (x, y) itself.
• a color longitudinal error can not only be deliberately set to zero with a different choice of optical media, but the element can also be designed so that defined amounts of longitudinal chromatic aberration are generated.
• a lateral displacement of the free-form elements according to equation (2) simultaneously produces a refractive power change at the central wavelength (ie a defocus) and relative thereto a longitudinal chromatic aberration the marginal or minor wavelengths.
• the solution proposed according to the invention consists in using for the free-form elements 1, 3 and the immersion medium 13, 17 arranged therebetween materials and media which are almost not in the refractive index n at the central wavelength but clearly in the Abbe number v differ from each other, especially those materials and media in which at the same time the conditions -n 2 ⁇ ⁇ 0.05 and
• the free-form elements 1, 3 are formed from plastic, as an immersion medium 13, 17, for example, with an appropriate alkali-doped aqueous (salt) solution into consideration.
• the conditions (9a) to (9c) can be understood from the following consideration: The more the Abbe number of free-form elements differs from the Abbe number of the immersion medium, the smaller the lateral displacement paths can be - and the flatter the freeform profiles 1, 3 can be Achieving a given color longitudinal error fail through the wavefront manipulator.
• the less the refractive index of the free-form elements differs from the refractive index of the immersion medium the lower the change in the focal position at the central wavelength when setting a predetermined chromatic aberration.
• equations (8a) to (8c) for example, with two optical elements 1, 3 whose free-form surfaces 5, 7 are given by the equation (5), a wavefront manipulator for influencing the so-called Gaussian error, that is, the image defect that describes the chromatic variation of the spherical aberration.
• a plurality of structural profiles can be freely superposed in the free-form surfaces 5, 7 of the optical components 1, 3.
• a structure for changing the refractive power and a structure for changing the spherical aberration in the free-form surfaces 5, 7 may be superimposed so that a corresponding zoom lens will vary a refractive power when the optical components 1, 3 are displaced while changing a spherical aberration, both Changes are proportional to each other with an arbitrarily but firmly preselected proportionality factor.
• the rules set out above for the effect of a corresponding choice of material according to condition (8a), (8b) or (8c) or according to the conditions (9a), (9b) or (9c) can be applied mutatis mutandis.
• the concrete example is based on a vario lens with two optical components 1, 3, each having a free-form surface 5, 7, whose shape is described by the polynomial winding according to equation (1).
• the development coefficients C m , n of the polynomial winding are in the design data listed in the following tables, respectively corresponding areas are indicated, wherein the development coefficients are marked with the powers of the associated polynomial terms.
• the associated coefficients k, A, B, C and D are indicated on the corresponding surfaces, respectively, following the vertex radius.
• the diameter of the aperture diaphragm is constant in the concrete embodiment, 20 mm.
• the procedure is three-step.
• First, in a first step, an optically group designed for a fixed average object distance of So -250 mm and quasi-defect-free for this fixed object distance is specified.
• a Vario-lens is added to vary the system's refractive power and thus adapt it to the changed object intercept.
• the Variolinse still has no immersion medium.
• a Variolinse invention with immersion medium is given, with It is possible to compensate the chromatic aberrations almost completely and over the entire distance range which can be set with the variolo- gy.
• the optics 20, which images almost faultlessly for a fixed mean object distance of So -250 mm, is represented in the concrete exemplary embodiment by a rotationally symmetrical hybrid optics, as shown schematically in FIG.
• the optical system 20 shown in FIG. 3 consists of a collecting lens made of the glass FK5, which is aspherical on the front side, and a spherical diverging lens made of the glass SF1 cemented thereto.
• the diverging lens is provided on the back (F7) with an adapted DOE structure.
• the optics 20 two plane-parallel glass plates 21, 23 are connected upstream.
• This part of the system is used here to simulate a virtually perfectly corrected fixed-focal-length optics, which, of course, can also be formed in practical applications by very differently constructed multi-lens objectives.
• the fixed focal length group is designed to image an object located 250 mm in front of the vertex of the leftmost glass surface F1 on an image plane 50 mm away from the vertex of the last, rightmost lens surface F7 ,
• an objective for a digital surgical microscope can be considered, ie a surgical microscope with digital eyepieces and / or another display.
• FIG. 4 shows the image error curves belonging to the optics from FIG.
• the vertical axis denotes the geometrical-optical transverse aberrations in millimeters and ranges from -0.05 mm to 0.05 mm.
• the left side which is referred to in the figure as Y-fan (German Y-fan), the transverse aberration for a beam in dependence on the Y-coordinate of the opening beam in the exit pupil.
• the right-hand side which in the figure is designated as an X-fan, shows a corresponding representation of the transverse aberration for the beam as a function of the X-fan. Coordinate of the opening beam in the exit pupil.
• the beam has an axis beam as the main beam, ie, the main beam is a beam that runs on the optical axis of the fixed focal length group 20, ie the X and Y coordinates has 0.0 and in the YZ plane and in the XZ Plane has the angle of incidence zero degrees with respect to the optical axis.
• the image point generated by the optics of a beam characterized by an axis beam as the main beam lies on the optical axis.
• the main ray of the beam in the Relative Field is corresponding to the Y coordinate 0.00 and the angle 0 ° for the Y fan and the X coordinate 0.00 and the angle 0 ° for the X-Fan marked.
• the two optical components 1, 3, each carrying a free-form surface 5, 7 on the inside, are laterally moved in opposite directions to each other to set the focus on the different object distances, so that a variable air lens results in the interior.
• the displacement paths of the first laterally moved optical component 1 in the 5 positions are +1.50 mm, +0.75 mm, 0.00 mm; -0.75 mm; -1.50 mm in the y direction.
• the second optical component 3 shifts in each case by equal amounts in the opposite direction, so that the displacement paths of the second laterally moving optical component 3 in the 5 positions -1.50 mm, -0.75 mm, 0.00 mm; +0.75 mm; +1.50 mm.
• the position of the image plane relative to the optics 20 remains constant (50 mm free cut width).
• FIGS. 10 to 14 show the aberrations associated with the positions of the optical components shown in FIGS. 5 to 9.
• the vertical axes in each case denote the geometric-optical transverse aberrations in millimeters and extend from -0.05 mm to 0.05 mm.
• the left side of the figures again shows the transverse aberration for a beam with axis beam as the main beam as a function of the Y-coordinate of the opening beam in the exit pupil, the right side a corresponding representation of the transverse aberration for the beam in dependence on the X-coordinate of Opening beam in the exit pupil. It can be seen from FIGS.
• Such an immersion oil is available, for example, from Zeiss under the name "Immersion Oil 518.” If these numbers are used in inequality 8a, the result is 0.00062, which is well below the limit of inequality (8a) and even below that in equation (8c) and thus results in a very good correction of the chromatic aberration shown in Figures 10 to 14.
• this inventive variola it is possible to achieve chromatic aberrations almost completely and over the entire adjustable distance range avoid.
• Figures 15 to 19 show the aberrations that occur in the festbrennweitigen optics 20 with upstream Vario according to the invention.
• the vertical axes each denote the geometrical-optical transverse aberrations in millimeters and range from -0.05 mm to 0.05 mm, the left side of the figures being the transverse aberration for a beam with the axis of the beam as the main beam as a function of the Y-coordinate of Opening beam in the exit pupil and the right side shows a corresponding representation of the transverse aberration for the beam in dependence on the X-coordinate of the opening beam in the exit pupil.
• FIG. 1 A third embodiment of a wavefront manipulator according to the invention is shown in FIG.
• the wavefront manipulator comprises two optical components 1, 3 which are arranged one behind the other along an optical axis OA and are arranged so as to be laterally displaceable relative to one another, ie perpendicular to the optical axis OA.
• Each of the two optical elements 1, 3 has a refractive free-form surface 5, 7 with an associated diffractive structure 25, 27.
• the wavefront manipulator is protected against leakage of the immersion liquid 13 by an elastic sealing collar 15, a sealing bellows or the like.
• an elastic sealing collar 15 a sealing bellows or the like.
• the material of the optical components 1, 3 and the immersion medium 13 are chosen so that their refractive indices have a difference which is a linear function of the wavelength.
• the lower refractive index material / medium has a higher dispersion than the higher refractive index material / medium.
• Such an optical element composed of a first material (in the present case the material of the optical components) and a second material (in this case the immersion medium) having different refractive indices and having a diffractive structure at the interface between the two materials also called efficiency achromatized diffractive optical element (EA-DOE).
• Efficiency achromatized diffractive optical elements and the conditions for a diffraction efficiency independent of the wavelength are described in detail, for example, in DE 10 2007 051 887 A1, to which reference is made in particular with regard to the conditions for a wavelength-independent diffraction efficiency.
• the conditions mentioned therein can be easily transferred to the present case where the second medium is an immersion medium.
• the wavefront manipulator according to the invention is also embodied as an efficiency-achromatized diffractive optical element, refractive and diffractive wavefront manipulators can be produced, for example those with variable refractive power, in which the diffraction efficiency of the diffractive structure 25, 27 varies only slightly over a wide wavelength range and False light is suppressed in unwanted diffraction orders.
• diffractive wavefront manipulators can also be realized in which the diffraction efficiency does not vary more than 5% over a wavelength range of at least 200 nm, in particular at least 300 nm, and in particular varies no more than 1% over a wavelength range of at least 200 nm.
• wavefront manipulators for the visible spectral range can be realized in which the diffraction efficiency in the range of 410 nm to 710 nm does not vary more than 5% and does not vary more than 1% in the range of 425 nm to 650 nm.
• the diffractive structure can be described by a polynomial winding corresponding to the polynomial winding for the freeform surfaces (equation (1)).
• the phase function ⁇ then has the form:
• C ' mn denotes the development coefficient of the polynomial winding of the diffractive structure 25, 27 in the order m with respect to the x direction and the order n with respect to the y direction.
• the coordinates x and y as well as the reference wavelength ⁇ are to be used in equation (10) as dimensionless numerical measures (so-called lens units) in millimeters.
• the diffractive structure described in this way can be physically imagined such that, starting from the support surface, which may be a free-form surface, a plane surface or a curved surface, the associated segment of the diffractive structure each leaps around one upon reaching a fixed phase value of 2 ⁇ Amount ⁇ / ( ⁇ ( ⁇ ) -1) in the z-direction relative to the support surface.
• the diffractive structure 25, 27 belonging to a refractive free-form surface 5, 7 is described by a polynomial winding which has non-zero development coefficients in the same polynomial orders as the polynomial winding of the refractive free-form surface 5, 7.
• Those development coefficients of a polynomial winding describing a refractive free-form surface 5, 7 and the polynomial winding describing the associated diffractive structure 25, 27, which are each assigned the same polynomial order, are in a fixed functional relationship to one another.
• the development coefficients of the free-form surface C m, n and the development coefficients of the diffractive structure C ' m , n are therefore different from zero with the same values of n and m and in particular coupled to each other by a fixed proportionality factor.
• the proportionality factor preferably depends on the dispersion in the material used of the optical components 1, 3 and is to be determined in each individual case from a numerical optimization calculation.
• the diffractive structure belonging to the refractive free-form surface according to equation (2) accordingly has the following defining equation: where the coefficient C is a constant proportional to K related to K in a manner dependent on the dispersion properties of the glass used and, in a concrete case, numerically determined. If, in order to minimize the center thickness of the optical component 1, 3, a term proportional to y is also added (wedge or tilt term) whose optical effect on the two free-form surfaces 5, 7 is almost canceled, but a minimization of the center thickness of the component 1, 3 of the element, the corresponding term can then also be provided in the diffractive structure.
• the phase function the diffractive surface 25, 27 and the height profile of the refractive free-form surface 5, 7 always contain the same polynomial terms - not necessarily in the diffractive structure 25, 27 may be provided. This is due to the fact that a pure tilting term on the free-form surfaces is optically ineffective to a first approximation.
• the associated phase function of the diffractive structure then has the following form:
• an exemplary embodiment of a wavefront manipulator is described below, in which four optical components 101, 103, 111, 113 are present.
• Two of the optical components together form an assembly 105, 115, which can be considered as a wavefront manipulator as described with reference to FIG. 1, FIG. 2 or FIG.
• the assemblies 105, 115 need not be the same design.
• one of the assemblies may be formed as a wavefront manipulator according to claim 1, the other as a wavefront manipulator according to claim 20.
• the four optical components 101, 103, 111, 113 form two assemblies 105, 115, each forming a wavefront manipulator according to FIG.
• the wavefront manipulator comprising the two subassemblies 105, 115 is arranged in the present exemplary embodiment in a zoom system which comprises four lens groups 107-110, which are shown in simplified form only as lenses in FIG.
• the two outer lens groups 107, 110 are fixed and collecting, the two inner lens groups 108, 109 displaceable and dispersive.
• the assemblies 105, 115 of the wavefront manipulator are positioned between the two inner lens groups 108, 109 in the region of an aperture diaphragm 106 - for example in front of and behind the aperture diaphragm 106, as indicated in the figure, where in a central zoom position a collimated beam path and in others Zommwolfen at least an approximately collimated beam path is present.
• the optical elements of the zoom system form a symmetrical arrangement with respect to the aperture diaphragm plane.
• the wavefront manipulator serves to bring about a trichromatic correction over the entire zoom range.
• the provision of diffractive structures, as described with reference to FIG. 20, also increases the number of degrees of freedom and thus also the number of possible corrections or reductions.
• the limitation of the lateral movement can then ensure, for example, that the sealing effect of the cuff, the bellows, etc. is ensured in any case over the entire lateral range of motion.
• other considerations such as a limitation of the space required for the wavefront manipulator, lead to a limitation of the lateral movement.
• a limitation of the lateral movement can, for example, be brought about by increasing the scaling factor k for the profile depth of the freeform surface given a given wavefront effect.
• the free-form surfaces of the optical components have been described as identical.
• the free-form surfaces there may be slight differences between the free-form surfaces, such as to account for non-paraxial effects due to the deviation of the incident height of rays at the first and second free-form surfaces due to the finite path in the immersion medium.
• the deviations must be determined empirically.
• the diffractive structure may be present on the planar surfaces instead of on the free-form surfaces, the optical components then facing one another with their plane surfaces and the immersion medium being arranged between the planar surfaces.
• the optical components can be arranged so that their planar surfaces face each other and the immersion medium is arranged between the planar surfaces.

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• 2012
  • 2012-02-16 DE DE201210101262 patent/DE102012101262B3/de active Active
• 2013
  • 2013-02-11 WO PCT/EP2013/052673 patent/WO2013120800A1/fr not_active Ceased

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