Method for producing an optical test element for determining an accuracy of an optical surface

Abstract

The invention relates to a method for producing an optical test element (19) for determining an accuracy of an optical surface (20), the method comprising the following steps: - determining a CGH design (24) suitable for measuring the optical surface (20), - generating a CGH auxiliary structure (25) corresponding to the CGH design (24) on an auxiliary substrate (30) with the aid of a direct write lithography method, - generating an image of the CGH auxiliary structure (25) on a final substrate (40) with the aid of a transfer lithography method, - generating a CGH structure (50) corresponding to the CGH design (24) using the generated image. The method offers the advantage that the auxiliary substrate can be generated with high precision independently of the size of the optical test element with the aid of a standardised direct write lithography system.

Description

Method for manufacturing an optical test element for determining a fit defect of an optical surface

[0001] The present patent application claims priority from German patent application DE 10 2024 207 299.0, filed on August 1, 2025, to which reference is made and whose content is fully incorporated herein ("incorporation by reference"). The invention relates to a method for manufacturing an optical test element for determining a fit defect of an optical surface.

[0002] It is generally known to use optical inspection elements in the form of a computer-generated hologram (CGH) for interferometric measurements to determine a fit error of an optical surface (WO 2005 / 114101 Al, DE 10 2015 202 695 Al, DE 10 2012 217 800 Al, DE 10 2019 204 096 Al). A portion of a test beam path striking the CGH, also referred to here as the input wave, is diffracted by the CGH in such a way that a resulting portion of the test beam path, hereinafter referred to as the output wave, forms a wavefront adapted to the nominal shape of the optical surface. This means that the output wave strikes the optical surface under test perpendicularly, provided that the optical surface corresponds to its nominal shape and is appropriately positioned. The output wave striking the optical surface is then reflected back on itself and used together with a reference beam path to generate an interference signal.The interference signal can be used to make statements about the fit of the optical element.

[0003] CGH typically exhibits a transparent or reflective substrate with a lattice-like microstructure. The optical surface is equipped with a grid-like structure. Different partial waves of the input wave encounter the grid-like structure at different points and undergo phase modulation, dependent on the grid structure, as they transition into corresponding partial waves of the output wave. On the optical surface under test, the different partial waves of the output wave interfere in such a way that the resulting wavefront is adapted to the desired shape of the optical surface. The desired phase modulation can be described by a phase function that describes the transition from the input wave to the output wave. If the phase function is available, a suitable CGH design can be determined computationally using known methods. The design can then be transferred to a CGH substrate using microstructuring techniques in a generally known manner.

[0004] For a CGH to generate an output wave that is reflected back on itself across the entire optical surface, the CGH must have a certain minimum extent in the area perpendicular to the optical axis of the input wave. This minimum extent depends on the size and curvature of the optical surface being tested. The larger and more convexly curved the optical surface, the larger the dimensions of the CGH must be to cover the entire surface. This is problematic because available methods for generating CGH microstructures reach their technical and physical limits when dealing with particularly large substrates.

[0005] To enable the measurement of large optical surfaces, prior art proposed arranging several separate CGHs into a single array, such that different parts of the input wave pass through different CGHs (see US 8,941, 837). However, this has the disadvantage that each CGH must be precisely calibrated. This is necessary, which involves considerable effort and the problem that the CGHs can drift relative to each other. Furthermore, gaps arise between the individual CGHs, for which no measurements can then be taken, especially in the case of freeform surfaces.

[0006] The object of the present invention is to at least partially avoid the disadvantages described above. This object is achieved by the features of the independent claims. Advantageous embodiments are described in the dependent claims.

[0007] Accordingly, the invention relates to a method for manufacturing an optical test element for determining a fit defect of an optical surface, comprising the following steps: - Determining a suitable CGH design for measuring the optical surface, - Generating a CGH auxiliary structure corresponding to the CGH design on an auxiliary substrate using a direct-write lithography process, - Generating an image of the CGH helper structure on a final substrate using a transfer lithography process, - Creating a CGH structure corresponding to the CGH design based on the generated image.

[0008] First, some terms used within the scope of the invention will be explained. The final substrate can be a transparent substrate, in particular made of quartz glass. The CGH structure can, for example, be formed by a sequence of raised areas or depressions in the substrate. It is also possible that the CGH structure is formed by a sequence of transparent and The CGH structure is formed in opaque areas. In a reflective CGH, the CGH structure can be formed by a sequence of structures with different reflectivities, for example, by a sequence of reflective and non-reflective areas or by elevations and depressions in a reflective layer. The final substrate containing the CGH structure forms the optical test element for determining a fit defect.

[0009] Direct writing lithography processes are defined as those lithography methods in which a desired structure is transferred onto a substrate using a spatially highly focused writing medium. Direct writing lithography can be, in particular, electron beam lithography or laser beam lithography. These two methods are characterized by the use of a spatially highly focused electron beam or laser beam to write a structure onto the substrate (or a resist layer located thereon). It may be possible for the writing medium (i.e., the electron beam or laser beam) to be moved over a limited distance relative to the fixed substrate by suitable deflection means. However, to write onto large substrates, it is necessary to move the substrate relative to the writing medium.

[0010] Transfer lithography processes are defined here as those processes that differ from direct-writing lithography processes in that a structure previously created, for example, on a mask or a die, is transferred over a large area onto the final substrate. An example of a transfer lithography process is nanoimprint lithography (also known as "nanoimprint lithography"), which is known from the prior art and involves the creation of microstructures on a "die". The microstructure is generated and mechanically transferred into a suitable coating that has previously been applied to a final substrate. Another example of a transfer lithography process is X-ray lithography, in which a microstructure generated on a mask is positioned at a short distance from a final substrate in order to transfer the microstructure to the final substrate by "shadowing".

[0011] Within the framework of the transfer lithography process, it can be provided that the image of the CGH aid structure is generated on the final substrate in a suitable coating applied to the final substrate. The generation of the CGH structure can then be carried out using generally known microstructuring methods based on the generated image.

[0012] It is not necessary for the CGH support structure to be identical to the CGH structure to be generated. In particular, it is possible for the CGH support structure to represent a "negative" of the CGH structure. This can be the case, for example, if nanoimprint lithography is chosen as the transfer lithography process, in which a structural maximum on the die (i.e., in this case, a maximum of the CGH support structure) is typically transferred to a structural minimum of a coating on the final substrate, whereby the structural minimum in the coating can be converted into a structural minimum of the CGH structure by a microstructuring process.

[0013] In conventional direct-write lithography processes, the substrate to be written is moved relative to the writing beam in order to create the desired microstructures across the entire substrate, since beam deflection can only expose small areas of a few hundred pm. This is particularly problematic with large-area lithography. For large substrates, these processes must be significantly accelerated and decelerated to keep the time required to write the microstructures across the large substrate area within acceptable limits. Direct-write lithography methods can therefore reach their mechanical limits with large substrates. In contrast, the method according to the invention allows a CGH support structure to be generated on a support substrate using a high-precision direct-write lithography process, whereby the size of the support substrate can be chosen independently of the size of the final substrate.

[0014] According to one implementation, the auxiliary substrate has a lower mass than the final substrate. In this implementation, a CGH auxiliary structure can first be produced on an auxiliary substrate with a lower mass than the final substrate using a direct-write lithography process. Due to its lower mass, the auxiliary substrate can be produced more easily and with higher positional accuracy. Only in a subsequent step is the CGH auxiliary structure transferred to the final substrate using the transfer lithography process. It was found that the high positional accuracy of the microstructures generated within the auxiliary substrate can be transferred to the CGH structure of the final substrate by the transfer lithography process without significantly impairing the positional accuracy.

[0015] In particular, the auxiliary substrate can have a smaller thickness than the final substrate. For example, the thickness of the auxiliary substrate can be less than or equal to 20 mm. The thickness of the final substrate can be, for example, between 30 mm and 200 mm, preferably between 50 mm and 120 mm. Furthermore, the ratio of the diameter of the final substrate to its thickness can be between 3:1. and 10:1, especially between 4:1 and 6:1. A final substrate of the aforementioned dimensions is regularly suitable for providing sufficient stability to the CGH during its subsequent use in measuring the optical surface. At the same time, the auxiliary substrate, with a thickness of 20 mm or less, can be produced much more easily using a standardized and highly accurate direct-write lithography process.

[0016] In one implementation, the determined CGH design is subdivided into a number of sub-designs, with the auxiliary substrate comprising a corresponding number of sub-substrates. The number of sub-designs is arbitrary. For example, the number of sub-designs can range from 2 to 36, and in particular from 4 to 16. The number of sub-designs can also be at least 50 or at least 100. Furthermore, the generation of the CGH auxiliary structure can involve creating a portion of the CGH auxiliary structure on each sub-substrate using one of the sub-designs. In this case, the CGH auxiliary structure is thus formed from the entirety of its parts located on separate sub-substrates.

[0017] By producing the CGH auxiliary structure not in one piece, but on multiple separate sub-substrates, each individual sub-substrate has a significantly smaller diameter and correspondingly lower weight compared to a corresponding CGH auxiliary structure produced in one piece. It is therefore possible to produce the components of the CGH auxiliary structure individually on each sub-substrate using a standardized and highly positionally accurate direct-write lithography process.

[0018] It may also be provided that the generation of an image of the CGH helper structure is carried out by creating images The components of the CGH helper structure are generated in sub-regions of the final substrate. In particular, the images of the different components can be generated successively in different sub-regions, so that the entire image of the CGH helper structure is assembled from the individual images of the components. In this way, a composite CGH structure can be generated in the final substrate that has a surface area many times larger than the individual components of the CGH helper structure.

[0019] In one implementation, after generating a first image of a first part of the CGH auxiliary structure in a first sub-area of ​​the final substrate, a second image of a second part of the CGH auxiliary structure is generated in a second sub-area of ​​the final substrate. During the generation of the second image, the second part of the CGH auxiliary structure is aligned relative to the first image. It has been shown that such alignment, based on a previously generated image, allows for highly accurate positioning of the images relative to each other, thus largely maintaining the accuracy achieved when generating the parts of the CGH auxiliary structure using the direct-write lithography process. The first and second sub-areas can be directly adjacent to each other to simplify the alignment.

[0020] In the manner described above, a highly accurate image of the entire CGH helper structure can be generated on the final substrate, which is then converted into a corresponding CGH structure using generally known microstructuring methods. Furthermore, it can be provided that the first image includes at least one first optical marker, with the second part of the CGH aid structure at least one second optical marker includes , where the first optical marker and the second optical marker are used to align the second part of the CGH help structure relative to the first image .

[0021] In an alternative implementation, after generating an initial image of a first part of the CGH support structure in a first sub-area, a first CGH sub-structure corresponding to a first sub-design is generated in that first sub-area based on the first image. This can be achieved, for example, by covering all sub-areas of the final substrate that differ from the first sub-area with a protective layer, so that a microstructuring process applied to the first sub-area, which converts the first image into the first CGH sub-structure, has no effect on the other sub-areas. In particular, the protective layer can be a lacquer layer that is applied to the substrate as part of the microstructuring process (for the fabrication of the first sub-area).The lacquer layer is thus structured in the first sub-area and used to create the first CGH sub-structure, while the lacquer layer remains unstructured in all other sub-areas, protecting the substrate in these locations. Subsequently, a second image of a second part of the CGH support structure can be created in a second sub-area of ​​the final substrate. The previously applied lacquer layer can be removed, and a new lacquer layer applied to the final substrate to create the corresponding CGH sub-structure in the second sub-area. During this creation of the second CGH sub-structure, all sub-areas that differ from the second sub-area, including the already structured first sub-area, can again be covered by a protective layer, which in turn is primarily formed by the unstructured lacquer layer used to create the second CGH sub-structure. The second image can be generated automatically. During the generation of the second image, the second part of the CGH auxiliary structure can be aligned relative to the first CGH substructure. In this implementation, an image is thus first converted into a corresponding substructure before another image is generated. In this implementation as well, the first and second sub-areas can be directly adjacent to each other to simplify alignment. Furthermore, in this implementation, the first CGH substructure can also include at least one first optical marker, and the second part of the CGH auxiliary structure includes at least one second optical marker, with the first and second optical markers being used to align the second part of the CGH auxiliary structure relative to the first CGH substructure.

[0022] The sub-substrates can be rectangular. Furthermore, the sub-substrates can have a side length between 5 cm and 40 cm, particularly between 10 cm and 20 cm. Standardized electron beam lithography systems are available for processing 6-inch substrates, providing both high writing speed and high positional accuracy. Therefore, the sub-substrates can have a side length of 6 inches (approximately 152 mm) to be used in such standard systems. The thickness of the sub-substrates can be less than 20 mm.

[0023] Advantageous embodiments of the invention are described below by way of example with reference to the drawings. They show: Fig. 1: A device for the intermetric determination of a fit error of an optical surface with an optical inspection element manufactured according to the invention; Fig. 2: a schematic representation of a CGH design determined within the framework of the manufacturing process according to the invention; Fig. 3: an auxiliary substrate used in the manufacturing process according to the invention in a cross-sectional view; Fig. 4: an auxiliary substrate used in the manufacturing process according to the invention with a CGH auxiliary structure in a cross-sectional view; Fig. 5: a final substrate with coatings used in the manufacturing process according to the invention in a cross-sectional view; Fig. 6: a schematic cross-sectional representation of the Auxiliary substrate of Figure 4 and final substrate of Figure 5 during the execution of a nanoimprint lithography process; Fig. 7: a cross-sectional view of the final substrate after preparation of a CGH structure; Fig. 8: a schematic representation of a CGH design determined within the framework of an alternative embodiment of the manufacturing process according to the invention, which is divided into several sub-designs; Fig. 9: a schematic representation of a partial design, a partial substrate and a part of a CGH auxiliary structure; Fig. 10: a schematic cross-sectional view of a Auxiliary substrate and a final substrate during the execution of a nanoimprint lithography process; Fig. 11: a cross-sectional view of the final substrate of Figure 10 after preparation of a CGH structure; Fig. 12: a cross-sectional view of an alternative CGH helper structure designed as a shadow mask.

[0024] Figure 1 shows a schematic representation of a device for the intermetric determination of a fit defect of an optical surface, in which an optical test element 19 manufactured according to the invention is used. The device comprises a light source 14, which in this embodiment is designed as the exit end of an optical fiber. The optical fiber is fed by a laser light source, which in this case is a helium-neon laser with a wavelength of approximately 633 nm. The beam path 15 exiting the optical fiber in a divergent state passes through a beam splitter 16 and is collimated with a collimator 17.

[0025] The collimated beam path strikes a Fizeau plate 18, where the light is partially reflected. The reflected components of the light form a reference beam path. The non-reflected components of the light form a test beam path.

[0026] The test beam passes through the optical test element 19, strikes an optical surface 20 of a mirror test piece, and is reflected back onto itself. The reflected beam- The projected test beam path interferes with the reference beam path and is directed via the beam splitter 16, an aperture 21, and an eyepiece 22 onto a detector 23 in the form of a CCD camera. An interferogram is recorded by the detector 23, from which the fit error in the examined optical surface 20 of the first mirror test specimen can be read.

[0027] The test beam path, which strikes the optical test element 19 as an input wave in the form of a plane wavefront, is transformed within the optical test element 19 into an output wave that forms a wavefront adapted to the surface shape of the optical surface 20 of the mirror test specimen. The output wave is shaped such that it strikes the entire optical surface 20 of the mirror test specimen perpendicularly, provided the mirror test specimen conforms to its nominal shape and is positioned in its nominal position relative to the optical test element 19. The mirror test specimen has a size of approximately 420 mm and is convexly curved. Due to the convex curvature, the test beam path reflected from the optical surface 20 widens in the direction of the optical test element 19.While it is possible to position the optical test element 19 near the optical surface 20 so that the reflected test beam path does not widen excessively before reaching the optical test element 19, its diameter must be at least as large as that of the optical surface to allow for complete measurement of the optical surface. In this case, the diameter of the optical test element is 450 mm. Figure 1 schematically indicates a CGH structure on the side of the optical test element 19 facing the mirror test specimen 20.

[0028] To produce the optical test element 19, a CGH design 24, suitable for measuring the optical surface 20, is first determined computationally in a generally known manner. The CGH design is schematically illustrated in Figure 2. Using the CGH design 24, a CGH structure 50 is generated on a final substrate 40 (see Figure 7). In this case, a quartz glass substrate with a thickness of approximately 80 mm and a diameter of 450 mm is used as the final substrate 40. The CGH structure 50 to be produced is formed by a sequence of protrusions and the spaces between them. In Figure 2, the position of the protrusions is illustrated by white lines and the position of the spaces by black lines.

[0029] The substrate 40 can have a diameter-to-thickness ratio between 4 and 10, for example, 6, 8, or 10. This provides sufficient stability to the substrate 40 and the optical test element 19 produced from it. If the optical test element 19 is too thin, there is a risk that it will deflect, thereby distorting the interferometric measurement. Due to the large dimensions of the substrate 40, available direct-write lithography processes, especially electron beam lithography, are unsuitable for structuring the substrate 40. The optical test element 19 was therefore produced using the method described below.

[0030] The process is illustrated with reference to Figures 3-7. In the process according to the invention, an auxiliary substrate 30 is provided, which is shown in Figure 3 in a transverse- A sectional view is shown. The auxiliary substrate 30 is made of transparent quartz glass and has a thickness of at least 5 mm, in particular at least 15 mm, preferably at least 25 mm. A hard mask 31, for example made of chromium, is applied to the auxiliary substrate 30. The hard mask is covered with a resist 32 suitable for electron beam lithography. Using an electron beam lithography process, an image of a CGH auxiliary structure is first created in the resist 32. Since the auxiliary substrate 30 is significantly thinner and therefore significantly lighter than the final substrate 40, this process can be carried out much faster and with significantly higher positional accuracy compared to a case in which the CGH structure is created directly on the final substrate 40 using electron beam lithography.

[0031] Based on the image, the CGH helper structure 25 is then generated on the helper substrate 30 (see Figure 4). A suitable method for microstructuring this, in which, among other things, the helper substrate 30 is selectively etched and the hard mask is subsequently removed, is generally known and therefore does not need to be explained in detail here.

[0032] The auxiliary substrate 30 with the CGH auxiliary structure 25 located on it is subsequently used as a stamp in a nanoembossing lithography process to create an image of the CGH auxiliary structure 25 on the final substrate 40. For this purpose, the final substrate 40 is coated with a hard mask 41 and with a resist 42 suitable for nanoembossing lithography (see Figure 5). The resist 42 has a certain viscosity, so that an image of the CGH auxiliary structure 25, formed by a depth profile, is embossed into the resist 42 when the CGH auxiliary structure 25 is brought into contact with the resist over its entire surface (see Figure 6). After the resist has cured, the CGH auxiliary structure can be removed, and the image remains in the resist. The hardening process can be supported, for example, by irradiation with UV light. Based on the depth profile embossed in the lacquer 42, a CGH structure 50 corresponding to the CGH design 24 can subsequently be generated on the final substrate 40 (see Figure 7). This can also be done using known microstructuring methods.

[0033] With reference to Figures 8-11, an alternative embodiment of the manufacturing process according to the invention is explained below. In this embodiment of the process, a particularly large optical test element with a diameter of at least 500 mm, in particular at least 600 mm, and with a thickness of at least 60 mm, at least 70 mm, or at least 80 mm is produced. In this embodiment as well, a CGH design 24, suitable for measuring an optical surface, is first determined computationally in a generally known manner. In contrast to the embodiment of Figures 2 to 7, this CGH design 24 is first subdivided into a number of, in this case, 16 sub-designs 241.

[0034] Subsequently, a number of 16 sub-substrates 301 are provided, with each sub-substrate 301 being assigned one of the sub-designs 241. The sub-substrates 301 are square and have a side length of 152 mm (approximately 6 inches) and a thickness of 10 mm. The sub-designs 241 can have a maximum side length of at most 200 mm, in particular at most 150 mm, and further, in particular, at most 100 mm. In this case, the side length of the sub-design 241 is smaller (for example, 140 mm) than the side length of the sub-substrates, so that the sub-designs 241 can each be applied completely to each of the sub-substrates 301, leaving a margin.

[0035] In the manner already described in connection with Figures 3 and 4, a first of the sub-designs 241 is used to create a corresponding first part 251 of a To produce a CGH support structure on a first sub-substrate 301. This is schematically illustrated in Figure 9. This process is repeated for each of the further 15 sub-substrates, so that different parts of the overall CGH support structure 25 are produced on each of the 16 sub-substrates. Since the sub-substrates have a side length of 152 mm (approximately 6 inches), standardized electron beam lithography systems can be used to produce the respective parts of the CGH support structure 25. The parts of the CGH support structure 25 can therefore be produced in an acceptable time and with the highest precision.

[0036] A final substrate 40 is then provided (see Figure 10) and prepared for nanoimprint lithography in the manner already described in conjunction with Figure 5. The first part 251 of the CGH support structure 25 shown in Figure 9 is used as a stamp during the nanoimprint lithography process to create an image of the first part 251 of the CGH support structure 25 in the resist 42 within a first sub-area 401 of the final substrate 40. A corresponding image is schematically illustrated in Figure 10 in the first sub-area 401 on the left side of the substrate 40, with the first part 251 of the CGH support structure 25 already removed.

[0037] Subsequently, in an analogous manner, a corresponding image of the second part 252 is generated in a second sub-area 402 adjacent to the first sub-area 401, using a second sub-substrate 302 and the second part 252 of the CGH support structure 25 located thereon. Figure 10 shows the second sub-substrate 302 shortly before it is brought into contact with the lacquer 42. The second sub-substrate 302, used as a stamp, is positioned relative to the image of the first part 251 of the CGH support structure located in the first sub-area 401. aligned. In a marginal region 303, the subsubstrates can have optical markers that can be aligned with previously generated optical markers in the marginal region of a generated image.

[0038] The process is repeated until images of all 16 parts of the CGH helper structure are present in corresponding further sub-regions of the substrate 40. Subsequently, the CGH structure 50 can be generated in the final substrate 40 analogously to the manner described in connection with Figures 6 and 7. This is illustrated in Figure 11, which shows a cross-sectional view of the parts 501-504 of the CGH structure 50 generated in sub-regions 401-404.

[0039] Alternatively, after generating an initial image of a first part 251 of the CGH support structure in the first sub-area 401, the remaining sub-areas are covered with a protective layer, and the first part 501 of the CGH structure is initially produced in the first sub-area 401. The protective layer ensures that the process steps used only result in structuring of the substrate 40 in the first sub-area 401. During subsequent structuring of the second sub-area 402 of the substrate 40, the second sub-substrate 302 can be aligned using the already generated first part 501 of the CGH structure 50. During the production of the second part 502 of the CGH structure, the already structured first part 501 of the CGH structure, as well as the still unstructured sub-areas of the substrate 40, are covered with a protective layer.Optical markers can also be used in this design to increase alignment accuracy.

[0040] As mentioned above, the CGH structure 50 to be generated in the implementation forms of Figures 2 to 11 is characterized by a sequence of elevations with intervening Interstices are formed. The CGH structure is generated by selectively removing part of the final substrate 40 using an etching process. Alternatively, the CGH structure 50 can also be formed by a sequence of opaque and transparent regions. Corresponding microstructuring methods for producing such a sequence are generally known, so a detailed description is omitted here.

[0041] In the manufacturing processes described above, an X-ray lithography process can be used instead of nanoimprint lithography to transfer the CGH auxiliary structure 25, or parts 251 and 252 of the CGH auxiliary structure 25, onto the final substrate 40. For this purpose, a shadow mask forming the CGH auxiliary structure 25 can be created in the CGH auxiliary substrate 30 instead of a punch. A corresponding CGH auxiliary structure 25 designed as a shadow mask is illustrated in a cross-sectional view in Figure 12. The shadow mask can have through holes or a sequence of transparent and opaque areas.Instead of the nanoimprint lithography process illustrated in Figure 6, the X-ray lithography process is carried out by positioning the shadow mask in close proximity to or in contact with the final substrate 40 and transferring the CGH helper structure 25 to the final substrate 40 by exposing the shadow mask with X-rays in a generally known manner.

Claims

Patent claims 1. Method for manufacturing an optical test element (19) for determining a fit defect of an optical surface (20) , comprising the following steps: - Determining a suitable CGH design (24) for measuring the optical surface (20) , - Generating a CGH auxiliary structure (25) corresponding to the CGH design (24) on an auxiliary substrate (30) using a direct-write lithography process , - Generating an image of the CGH helper structure (25) on a final substrate (40) using a transfer lithography process , - Production of a CGH structure (50) corresponding to the CGH design (24) using the generated image, wherein the auxiliary substrate (30) with the CGH auxiliary structure (25) located on it is used as a stamp to produce the image of the CGH auxiliary structure (25) on the final substrate (40).

2. The method of claim 1, wherein the auxiliary substrate (30) has a lower mass than the final substrate (40).

3. Method according to claim 1 or 2, wherein the auxiliary substrate (30) has a smaller thickness than the final substrate (40) , wherein the thickness of the auxiliary substrate (30) is preferably less than or equal to 20 mm.

4. Method according to any one of claims 1 to 3, wherein the final substrate (40) has a diameter and a thickness- exhibits a diameter-to-thickness ratio between 3:1 and 10:1, preferably between 4:1 and 6:

1.

5. Method according to any one of claims 1 to 4, wherein the transferring lithography method is selected from the group comprising nano-embossing lithography and X-ray lithography.

6. Method according to any one of claims 1 to 5, wherein the direct writing lithography for generating the CGH auxiliary structure (25) is selected from electron beam lithography and laser beam lithography.

7. Method according to any one of claims 1 to 6, wherein the determined CGH design (24) is divided into a number of sub-designs (241) is subdivided, wherein the auxiliary substrate (30) is formed by a number of sub-substrates (301), wherein the generation of the CGH auxiliary structure comprises generating on each of the sub-substrates (301) a part (251, 252) of the CGH auxiliary structure using each of the sub-designs (241).

8. Method according to claim 7, wherein the generation of an image of the CGH auxiliary structure is carried out by generating images of the parts (251, 252) of the CGH auxiliary structure in sub-regions (401, 402, 403, 404) of the final substrate (40).

9. Method according to claim 8, in which, after generating a first image of a first part (251) of the CGH auxiliary structure in a first sub-area (401), a second image of a second part (252) of the CGH auxiliary structure is generated in a second sub-area (402), wherein the second part (252) of the CGH auxiliary structure is generated the second image is aligned relative to the first image.

10. The method of claim 9, wherein the first image comprises at least one first optical marker, wherein the second part (252) of the CGH auxiliary structure comprises at least one second optical marker, wherein the first optical marker and the second optical marker are used to align the second part (252) of the CGH auxiliary structure relative to the first image.

11. Method according to claim 8, wherein after generating a first image of a first part (251) of the CGH auxiliary structure in a first sub-area (401), a first CGH sub-structure (501) corresponding to a first part design (241) is first generated in the first sub-area (401) based on the first image, wherein a second image of a second part (252) of the CGH auxiliary structure is subsequently generated in a second sub-area (402), and wherein the second part (252) of the CGH auxiliary structure is aligned relative to the first CGH sub-structure (501) when generating the second image.

12. Method according to claim 11, wherein the first CGH substructure (501) comprises at least one first optical marker, wherein the second part (252) of the CGH auxiliary structure comprises at least one second optical marker, wherein the first optical marker and the second optical marker are used to align the second part (252) of the CGH auxiliary structure relative to the first CGH substructure (501).

13. Method according to any one of claims 7 to 12, wherein the number of part designs is between 2 and 36, preferably between 4 and 16.

14. Method according to any one of claims 7 to 13, wherein the Sub-substrates (301) have a side length that is between 5 cm and 40 cm, preferably between 10 cm and 20 cm, and further preferably about 152 mm.

15. Method according to any one of claims 7 to 14, wherein the Sub-substrates have a thickness of less than 20 mm.

16. Optical test element (19) for determining a fit defect of an optical surface (20) comprising a substrate (40) with a CGH structure (50) produced thereon, characterized in that the optical test element (19) is produced by a method according to one of claims 1 to 15.

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