阅读说明：本技术 用于制造计算机生成的全息图的方法和设备、全息图以及用于车辆的照明装置 (Method and device for producing a computer-generated hologram, hologram and lighting device for a vehicle ) 是由 M·吉尔 于 2020-03-20 设计创作，主要内容包括：用于制造计算机生成的全息图的方法,包括如下方法步骤：产生参考光束(4、4’)；产生物体光束(3)；将有关全息图的计算机生成的信息调制到物体光束(3)上；使物体光束(3)和参考光束(4、4’)在光敏的记录材料(1)上或中叠加以曝光全息图,依次对光敏的记录材料(1)的多个区段分别同时加载物体光束(3)和参考光束(4、4’),以便制造多个子全息图,所述参考光束(4、4’)照射到记录材料(1)的第一区段的表面上的照射角(α)与参考光束(4、4’)照射到记录材料(1)的第二区段的表面上的照射角(α’)不同,参考光束(4、4’)的照射角(α、α’)的改变通过改变参考光束(4、4’)在透镜(9a、13a)上的照射点来实现,参考光束(4、4’)在通向光敏的记录材料(1)的路径上穿过所述透镜。(Method for producing a computer-generated hologram, comprising the method steps of: generating a reference beam (4, 4'); generating an object beam (3); modulating computer-generated information about the hologram onto the object beam (3); superimposing the object beam (3) and the reference beam (4, 4 ') on or in the light-sensitive recording material (1) for exposing a hologram, successively simultaneously applying the object beam (3) and the reference beam (4, 4') to a plurality of sections of the light-sensitive recording material (1), respectively, in order to produce a plurality of sub-holograms, the irradiation angle (alpha) at which the reference beam (4, 4 ') impinges on the surface of a first section of the recording material (1) differs from the irradiation angle (alpha ') at which the reference beam (4, 4 ') impinges on the surface of a second section of the recording material (1), the variation of the irradiation angle (alpha, alpha ') of the reference beam (4, 4 ') being effected by varying the point of impingement of the reference beam (4, 4 ') on a lens (9a, 13a) through which the reference beam (4, 4 ') passes on its way to the light-sensitive recording material (1).)

1. Method for producing a computer-generated hologram, comprising the following method steps:

-generating a reference beam (4, 4'),

-generating an object beam (3),

-modulating computer-generated information about the hologram onto the object beam (3),

-superimposing an object beam (3) and a reference beam (4, 4 ') on or in a photosensitive recording material (1) to expose a hologram, sequentially loading the object beam (3) and the reference beam (4, 4') simultaneously respectively for a plurality of sections of said photosensitive recording material (1) in order to produce a plurality of sub-holograms,

characterized in that the irradiation angle (α) at which the reference beam (4, 4 ') is irradiated onto the surface of the first section of the recording material (1) is different from the irradiation angle (α ') at which the reference beam (4, 4 ') is irradiated onto the surface of the second section of the recording material (1), the change of the irradiation angle (α, α ') of the reference beam (4, 4 ') being effected by changing the irradiation point of the reference beam (4, 4 ') on a lens (9a, 13a) through which the reference beam (4, 4 ') passes on its way to the photosensitive recording material (1).

2. Method according to claim 1, characterized in that the different irradiation angles (α, α ') of the reference beam (4, 4 ') on the surface of the sections of the recording material (1) are produced by different radial distances between the optical axis (11) of the lens (9a, 13a) and the irradiation point of the reference beam (4, 4 ') on the lens (9a, 13 a).

3. A method as claimed in any one of claims 1 or 2, characterized in that the photosensitive recording material (1) has a flat surface.

4. Method according to any one of claims 1 to 3, characterized in that the photosensitive recording material (1) is moved between the exposure with the object beam (3) and the reference beam (4, 4 ') for producing the first sub-hologram and the exposure with the object beam (3) and the reference beam (4, 4') for producing the second sub-hologram, in particular in a plane parallel to the planar surface of the recording material (1).

5. Method according to claim 4, characterized in that the optical axis (11) of the lens (9a, 13a) is oriented perpendicular to the plane in which the photosensitive recording material (1) is moved between the production of the two sub-holograms.

6. The method according to any one of claims 1 to 5, wherein the computer-generated hologram produced is a transmission hologram or a reflection hologram or an edge-illuminated hologram.

7. The method of any one of claims 1 to 6, wherein the manufactured computer-generated hologram is used as a master hologram for manufacturing a replica hologram.

8. Apparatus for producing a computer-generated hologram, the apparatus comprising:

a light source, in particular a laser light source for generating a light beam,

-optics for splitting the light beam generated by the light source into an object light beam (3) and a reference light beam (4, 4'),

-modulation means for modulating information about the hologram onto the object beam (3),

-optics for superimposing the object beam (3) and the reference beam (4, 4 ') on or in the light-sensitive recording material (1) for exposing a hologram, in operation of which apparatus the object beam (3) and the reference beam (4, 4') are simultaneously loaded in succession onto a plurality of sections of the light-sensitive recording material (1) respectively in order to produce sub-holograms,

characterized in that the optics for superimposing the object beam (3) and the reference beam (4, 4') are configured such that, so that an irradiation angle (alpha) at which the reference beam (4, 4 ') is irradiated onto the surface of the first section of the recording material (1) is different from an irradiation angle (alpha ') at which the reference beam (4, 4 ') is irradiated onto the surface of the second section of the recording material (1), the optics for superimposing the object beam (3) and the reference beam (4, 4 ') comprise at least one lens (9a, 13a) through which the reference beam (4, 4') can pass on its way to the photosensitive recording material (1), and the variation of the illumination angle (α, α ') of the reference beam (4, 4 ') is achieved by varying the illumination point of the reference beam (4, 4 ') on the at least one lens (9a, 13 a).

9. The apparatus according to claim 8, characterized in that it is adapted to carry out the method according to any one of claims 1 to 7.

10. The device according to any one of claims 8 or 9, characterized in that the device comprises at least one lens (9a, 13a) on mutually opposite sides of the photosensitive recording material (1), through which lens the reference beam (4, 4 ') can pass on its way to the photosensitive recording material (1), the change of the irradiation angle (α, α') of the reference beam (4, 4 ') being achieved by changing the irradiation point of the reference beam (4, 4') on one of the lenses (9a, 13 a).

11. Device according to any one of claims 8 to 10, characterized in that the at least one lens (9a, 13a) is part of a lens system, in particular a lens system (9, 13) consisting of two or more lenses (9a, 9 b; 13a, 13b), through which the reference beam (4, 4') can pass on its way to the photosensitive recording material (1).

12. Device according to any of claims 8 to 11, characterized in that the device comprises an impregnating agent (10), such as an impregnating liquid, which is arranged between the at least one lens (9a, 13a) or a lens (9a, 9 b; 13a, 13b) of the lens system (9, 13) and the photosensitive recording material (1) or the substrate (2a, 2b) carrying the photosensitive recording material (1).

13. The device according to any one of claims 8 to 12, characterized in that it comprises a nested mirror (6) with which the extension of the reference beam (4, 4') can be varied, in particular reduced.

14. Hologram, in particular replica hologram, produced by a method according to one of claims 1 to 7 and/or by means of a device according to one of claims 8 to 13, wherein the hologram is in particular provided for application on a curved surface and/or for use with a light source having a predefined divergence.

15. Lighting device for a vehicle, in particular a headlight for a vehicle, comprising a hologram according to claim 14, wherein the lighting device in particular comprises a curved surface on which the hologram is arranged.

Technical Field

The present invention relates to a method for producing a computer-generated hologram according to the preamble of claim 1, to a device for producing a computer-generated hologram according to the preamble of claim 8, to a hologram produced by such a method and/or produced with such a device, and to a lighting device for a vehicle having such a hologram.

Background

A method, a device, a hologram and a lighting device of the type mentioned at the outset are known from DE102016107210a 1. In the method described therein, a hologram consisting of a plurality of sub-holograms is exposed to a photosensitive recording material. In this case, the sections of the recording material corresponding to the individual sub-holograms are successively loaded with the object beam and the reference beam. The object beam is modulated by a light modulator with computer-generated hologram information. The hologram or a replica hologram produced with the hologram as master hologram can be integrated into a headlight of a motor vehicle.

The characteristics of the light source used for reconstruction play a decisive role in the manufacture of the hologram. Variations in the characteristics (e.g., divergence) of the light source used to reconstruct the hologram relative to the light source used in the manufacturing process result in dramatic variations in the reconstructed image. The same applies to the modification of the geometry of the substrate to which the hologram is applied. The equipment used to make computer-generated holograms is generally limited to simple substrate shapes. Free-form substrates are only restrictively feasible or infeasible. Computer-generated holograms or sub-holograms contained by said holograms are not optimized in the prior art with regard to their reconstruction angle with regard to the radiation characteristics of the different light sources, and the methods for production are limited to transmission holograms, reflection holograms or edge-illuminated holograms.

Disclosure of Invention

The invention is based on the problem of providing a method and a device of the type mentioned at the outset which allow the characteristics of the light source used for reconstructing the hologram and/or the geometry of the substrate to which the hologram should be applied to be taken into account when producing the hologram. Furthermore, a hologram produced by such a method and/or produced with such a device and a lighting device for a vehicle having such a hologram are to be specified.

This is achieved according to the invention by a method of the type mentioned at the outset having the features of the characterizing portion of claim 1, by an apparatus of the type mentioned at the outset having the features of claim 8, by a hologram having the features of claim 14 and by a lighting device having the features of claim 15. The dependent claims relate to preferred embodiments of the invention.

According to claim 1, it is provided that the irradiation angle at which the reference beam impinges on the surface of the first section of the recording material differs from the irradiation angle at which the reference beam impinges on the surface of the second section of the recording material, wherein the change in the irradiation angle of the reference beam is effected by a change in the irradiation point of the reference beam on a lens through which the reference beam passes on its way to the photosensitive recording material. In this way, different sub-holograms can be read in with reference beams of different illumination angles, so that the characteristics of the light source used to reconstruct the hologram and/or the geometry of the substrate can be taken into account when writing the hologram. For example, different illumination angles of the reference beam can be selected for different sub-holograms depending on the divergence of the light source used for the reconstruction or depending on the curvature of the substrate to which the hologram should be applied. In this case, it is possible to adapt the angle between the reference beam and the object beam for each sub-hologram almost continuously, and thus to create a precondition for a curved substrate, and to enable different radiation characteristics to be adapted to the respective light source. By changing the irradiation point of the reference beam on the lens, the irradiation angle of the reference beam on the recording material can be changed in a simple manner.

For example, different illumination angles of the reference beam on the surface of the sections of recording material can be produced by different radial distances between the optical axis of the lens and the point of illumination of the reference beam on the lens. For this purpose, the reference beam may impinge on the lens parallel to the optical axis of the lens.

The following possibilities exist: the photosensitive recording material has a flat surface. Nevertheless, it is possible to achieve by the method according to the invention that the hologram can be reconstructed after application to a curved substrate.

It can be provided that the photosensitive recording material is moved between the exposure with the object beam and the reference beam for producing the first sub-hologram and the exposure with the object beam and the reference beam for producing the second sub-hologram, in particular in a plane parallel to the planar surface of the recording material. In this way, the respective sub-holograms can be written sequentially.

The optical axis of the lens can be oriented perpendicular to the plane in which the photosensitive recording material is moved between the production of the two sub-holograms.

The following possibilities exist: the computer-generated hologram produced is a transmission hologram or a reflection hologram or an edge-illuminated hologram. In this case, it is possible to produce both transmission holograms, reflection holograms and edge-illuminated holograms with the aid of a single design structure.

It may be provided that the produced computer-generated hologram is used as a master hologram for producing a replica hologram. The replica holographic legend may be read into a thin, flexible film, for example. The film can then be applied, for example, to a curved surface of the lighting device, in particular of the headlight.

According to claim 8, it is provided that the optics for superimposing the object beam and the reference beam are designed such that the irradiation angle at which the reference beam impinges on the surface of the first section of the recording material differs from the irradiation angle at which the reference beam impinges on the surface of the second section of the recording material, wherein the optics for superimposing the object beam and the reference beam comprise at least one lens through which the reference beam can pass on its way to the photosensitive recording material, and wherein the change in the irradiation angle of the reference beam is achieved by changing the irradiation point of the reference beam on the at least one lens. The device allows flexible production of holograms which can be adapted for application to curved substrates and to arbitrarily radiated light sources.

It can be provided that the device is suitable for carrying out the method according to the invention.

The following possibilities exist: the device comprises at least one lens on mutually opposite sides of the photosensitive recording material, through which the reference beam can pass on its way to the photosensitive recording material, wherein a change of the irradiation angle of the reference beam is effected by changing the irradiation point of the reference beam on one of the lenses. In this way, the reference beam can be selectively irradiated onto the photosensitive recording material from the same side as the object beam or from the opposite side to the object beam. Thereby, not only a transmission hologram but also a reflection hologram can be manufactured.

It can be provided that the at least one lens is part of a lens system, in particular a lens system consisting of two or more lenses, through which the reference beam can pass on its way to the photosensitive recording material. The lens can be designed more simply by using a lens system consisting of more than one lens, on the surface of which a variable irradiation point of the reference beam is arranged.

The following possibilities exist: the device comprises an impregnating agent, for example an impregnating liquid, which is arranged between the at least one lens or the lens of the lens system and the photosensitive recording material or the substrate carrying the photosensitive recording material. The angle between the optical axis of the lens and the reference beam can be selected to be large by using an immersion agent such that the irradiation angle of the reference beam onto the photosensitive recording material or onto the substrate carrying the recording material lies within the range of the critical angle of total reflection. Thereby an edge-illuminated hologram can be manufactured.

Provision may be made for the device to comprise a nested mirror (Teleskop) with which the extent of the reference beam can be varied, in particular reduced. By reducing the extension of the reference beam, the change of the irradiation angle of the reference beam on the photosensitive recording material can be controlled more easily.

It can be provided that the apparatus comprises a movement device for moving the photosensitive recording material between the exposure with the object beam and the reference beam for producing the first sub-hologram and the exposure with the object beam and the reference beam for producing the second sub-hologram, wherein the movement device can move the recording material in particular in a plane parallel to a planar surface of the recording material.

The following possibilities exist: the modulation device for modulating the information about the hologram onto the object beam is designed as a liquid crystal display, preferably as a liquid crystal display operating in a reflective arrangement, which can produce a phase shift between different sections of the object beam.

According to claim 14, a hologram, in particular a replica hologram, is produced by the method according to the invention and/or by the device according to the invention, wherein the hologram is in particular provided for application on a curved surface and/or for use with a light source having a predefined divergence.

According to claim 15, a lighting device for a vehicle, in particular a headlight for a vehicle, comprises a hologram according to the invention, wherein the lighting device in particular comprises a curved surface on which the hologram is arranged.

Drawings

The invention is explained in more detail below with the aid of the figures. In the figure:

fig. 1 shows a part of a first embodiment of a device according to the invention in a side view;

fig. 2 shows a part of a second embodiment of the device according to the invention in a side view;

FIG. 3 shows a first embodiment of reconstruction of a hologram according to the invention in a schematic sectional view;

fig. 4 shows a second exemplary embodiment of the reconstruction of a hologram according to the invention in a schematic sectional view.

Detailed Description

In the figures, identical and functionally identical components are provided with the same reference symbols. Furthermore, a cartesian coordinate system is plotted in fig. 1 and 2, respectively, wherein the y direction extends into the drawing plane.

In the exemplary embodiment shown in fig. 1, a hologram made up of a plurality of sub-holograms should be exposed to the photosensitive recording material 1. The sub-holograms may be arranged side by side in a two-dimensional matrix in the x-direction and in the y-direction. As the photosensitive recording material 1, a material commonly used in the production of holograms can be considered.

The recording material 1 can be configured, for example, as a film arranged on a transparent substrate. In the embodiment shown, the substrates 2a, 2b are arranged not only on the upper side but also on the lower side of the photosensitive recording material 1. The photosensitive recording material 1 has a flat surface and extends in the x-y plane.

The first embodiment of the device according to the invention, which is partially schematically shown in fig. 1, also comprises a laser light source, not shown, which generates a laser beam, which is split by optics, also not shown, into an object beam 3 and a reference beam 4. The device further comprises a not shown modulation means which can be constructed, for example, as a liquid crystal display in a reflective arrangement. The liquid crystal display may be controlled in accordance with computer generated data relating to the manufacture of the individual sub-holograms.

The object beam 3 can be expanded onto the liquid crystal display by means of optics, which are also not shown. Depending on the data for driving the liquid crystal display, the liquid crystal display may change the phase of a part of the object beam 3 upon reflection, such that a part of the object beam 3 has a phase shift with respect to other parts of the object beam 3. Thereby, information about the sub-holograms is modulated onto the object beam 3.

The apparatus further comprises a lens system 5 serving as an objective lens, which lens system consists of two lenses 5a, 5 b. The object beam 3 passes through the lens system 5, wherein the object beam is focused by the lens system 5 into the recording material 1 from below or in the positive z direction in fig. 1.

The device according to fig. 1 further comprises a nested mirror 6 consisting of two lenses 6a, 6b, through which the reference beam 4 passes and which reduces the extension of the reference beam 4 in the lateral direction. After passing through the nested mirror 6, the reference beam 4 is deflected by 90 ° by the two mirrors 7, 8, respectively, so that it then extends in the negative z direction or downward direction in fig. 1.

The device further comprises a lens system 9 serving as an objective lens, which lens system consists of two lenses 9a, 9 b. The reference beam 4 passes through the lens system 9, wherein the reference beam is focused by the lens system 9 into the recording material 1 from above or in the negative z direction in fig. 1. An impregnating agent 10, such as an impregnating liquid, is provided between the lens 9b of the lens system 9, which is disposed closer to the substrate 2a of the recording material 1, and the substrate 2 a.

In the recording material 1, the reference beam 4 is superimposed with the object beam 3. By interference of the object beam 3 with the reference beam 4, a hologram is written into the photosensitive recording material 1 in a manner known per se. In the embodiment shown in fig. 1, a reflection hologram can be written by the reference beam 4 impinging on the side of the photosensitive recording material 1 facing away from the object beam 3.

The reference beam 4 impinges on the lens 9a parallel to the optical axis 11 of the lens 9 a. A more or less large irradiation angle α is obtained from the distance of the point of irradiation of the reference beam 4 on the lens 9a from the optical axis, at which the reference beam 4 is irradiated onto the surface of the recording material. It proves helpful here that the reference beam 4 has a small extent in the transverse direction due to the passage through the nested mirror 6.

The first of the two mirrors 7, 8 can be moved in the z direction along arrow 12 and can be moved in the y direction into the drawing plane of fig. 1 or out of the drawing plane in order to be able to change the entire solid angle. Movement in the z direction here changes the angle in the x-z plane, whereas movement in the y direction here changes the angle in the z-y plane.

Different points of illumination of the reference beam 4 on the lens 9a result in different positions of the mirror 7. Two exemplary positions of the mirrors 7, 7 'and, respectively, two reference beams 4, 4' corresponding thereto, which each impinge on the lens 9a in the negative z direction and in this case have different distances from the optical axis 11 of the lens 9a, are plotted in fig. 1. Accordingly, the angles α, α' at which the two reference beams are irradiated onto the recording material 1 are also different.

The reference beam 4 'irradiated onto the lens 9a near the optical axis 11 in fig. 1 is irradiated onto the surface of the recording material 1 at a relatively large irradiation angle α' with respect to the x-y plane. Whereas the irradiation angle α at which the reference beam 4 irradiated onto the lens 9a farther from the optical axis 11 in fig. 1 is irradiated onto the surface of the recording material 1 is significantly smaller than the irradiation angle α'. Thus, a positional variation of the reference beam 4, 4 ' causes a change of the irradiation angle α, α ' of the reference beam 4, 4 ' onto the recording material 1 and thus also a change of the orientation of the bragg plane in the hologram and a change of the irradiation angle at which the hologram can be reconstructed afterwards.

The lens system 9 assumes two functions. On the one hand, the lens system serves to focus the reference beam 4, 4 ' onto or into the recording material 1, and on the other hand the lens system enables to vary the irradiation angle α, α ' of the reference beam 4, 4 '. The recording material 1 is here supported movably in the x-y plane in the focal plane of the lens system 9. Suitable movement means for moving the photosensitive recording material 1 are provided for this purpose.

To produce a hologram, the recording material 1 can be positioned in the x-y plane in such a way that the object beam 3 and the reference beams 4, 4' are superimposed on a first section of the surface of the recording material 1 in order to expose a first sub-hologram. For this purpose, information about the first sub-hologram is modulated onto the object beam 3.

After the first sub-hologram is read in, the recording material 1 is moved in the x-y plane until the object beam 3 and the reference beams 4, 4' are superimposed on a second section of the surface of the recording material 1 in order to expose a second sub-hologram. For this purpose, information about the second sub-hologram is modulated onto the object beam 3.

In this way, all the sub-holograms are gradually read into the recording material 1.

If the reference beam 4, 4' impinges on the edge region of the lens 9a, an impingement angle which is equal to the critical angle for total reflection at the interface from the substrate 2a to the surroundings can be achieved on the basis of the immersion agent 10. In this way, a reflection-edge illuminated hologram can be produced with the embodiment according to fig. 1.

The second embodiment of the device according to the invention shown in fig. 2 differs from the first embodiment in particular in that the objective 13 arranged on the underside of the recording material 1 or on the object beam side is constructed identically to the objective 9 arranged above the recording material 1. The objective likewise has two lenses 13a, 13b, wherein an impregnating agent 10, for example an impregnating solution, is arranged between the lens 13b of the lens system 13 which is arranged closer to the substrate 2b of the recording material 1 and the substrate 2 b.

In this embodiment, not only the object beam 3 but also the reference beam 4 may pass through the lens system 13. For this purpose, the nested mirror 6 and the movable mirror 7 are arranged slightly further down, so that the reference beam 4 exiting from the mirror 7 can be reflected by the beam splitter serving as a beam combiner 14 up onto the objective 13. In this case too, different positions of the mirror 7 result in different illumination points of the reference beam 4 on the lens 13a or in different distances of the illumination points of the reference beam 4 from the optical axis 11 of the lens 13 a.

The object beam 3 may also pass upwards through the beam combiner. A transmission hologram can be written by irradiation of the reference beam 4 on the side of the recording material 1 facing the object beam 3. This corresponds in fig. 2 to the superposition of the object beam 3 and the reference beam 4 impinging on the recording material 1 from below on the recording material 1.

If the reference beam 4, 4' impinges on the edge region of the lens 13a, an impingement angle can be achieved on the basis of the immersion agent 10 which is equal to the critical angle for total reflection at the interface from the substrate 2b to the surroundings. In this way, a transmission-edge illuminated hologram can be produced with the embodiment according to fig. 2.

In the embodiment according to fig. 2, there is also provided a lens system 9 and a second mirror 8 arranged above the recording material 1. The embodiment shown in fig. 2 can therefore be used for writing reflection holograms after moving first mirror 7 up into the dashed position of mirror 7 ', wherein reference beam 4' corresponds here to the beam plotted in dashed lines.

Alternatively, the upper lens system 9 and the second mirror 8 can also be omitted in the second embodiment, so that only transmission holograms can be written with this apparatus.

The flexibility of exposing holograms at different angles allows for targeted matching to divergent light sources.

Fig. 3 shows a Light Emitting Diode (LED)15 as a divergent light source and the light 16 emitted from said LED or the wave front 17 of the light 16. If the component 18 of the first diffraction order of the hologram reconstructed by the light 16 should move in the same direction upwards in fig. 3 despite the divergence of the light 16, the bragg planes 19 of the hologram must form different angles with the surface of the recording material 1 for different sub-holograms. For example, in FIG. 3, the angle β of the right Bragg plane 19₁Angle beta significantly larger than the bragg plane 19 on the left₂。

It should be noted here that instead of a thin recording material 1, only a relatively thick plate is shown in fig. 3 and 4. In this case, it can be a transparent substrate on which the recording material is applied, for example, in the form of a film.

With the apparatus according to fig. 1 and 2 or by the method according to the invention, a suitable irradiation angle of the reference beam 4, 4' onto the recording material 1 can be selected during writing of the hologram into the recording material 1 in order to achieve a suitable slope of the bragg plane 19 in the hologram. In the production of the computer-generated hologram, the slope of the bragg plane 19, which is suitable for the diverging light source, can be taken into account without the light-emitting diode 15 itself having to be used in the writing process.

In the reconstruction example according to fig. 4, light-emitting diodes 15 are likewise used as divergent light sources. The recording material 1 or the substrate carrying the recording material 1 is not flat but curved or has a curved surface.

The bragg planes 19 of the individual sub-holograms which are inclined to one another as a result of the divergent light source must have an additional slope change as a result of the curvature of the marking material 1 containing the hologram. This is illustrated in fig. 4 by the effective bragg plane 20 reflecting the change in the bragg plane caused by the curvature of the recording material 1 used as the hologram carrier. Such an angular change of the effective bragg plane 20 when the recording material 1 is bent with respect to the flat surface 21 exemplarily plotted in fig. 4 can also already be taken into account during writing without having to use a bent recording material during writing.

A computer-generated hologram produced with the device according to fig. 1 and 2 or by the method according to the invention can be used as a master hologram for producing a replica hologram. The replica hologram can be read into a thin, flexible film, for example. The film can then be applied, for example, to a curved surface of the lighting device, in particular of the headlight.

List of reference numerals

1 photosensitive recording material

2a, 2b substrate

3 object beam

4. 4' reference beam

5 lens system

5a, 5b lens of the lens system 5

6 nested mirror

6a, 6b nested lenses of mirror 6

7 Movable mirror

8 reflecting mirror

9 lens system

9a, 9b lens of the lens system 9

10 impregnating agent

11 optical axes of lens 9a and lens 13a

12 arrows showing the movement of the mirror 7

13 lens system

13a, 13b lens of the lens system 13

14 beam combiner

15 light emitting diode

16 light emitted from the light emitting diode 15

17 wavefront of light 16

18 component of the first diffraction order of the reconstructed hologram

19 bragg planes

20 effective bragg planes

21 flat face

Angle of irradiation of alpha, alpha' reference beam 4 onto recording material 1

β₁、β₂The angle between the Bragg plane 19 and the surface of the recording material 1