Planar micro-nano structure reflector processing method and planar micro-nano structure reflector

Abstract

The invention provides a plane micro-nano structure reflecting mirror machining method and a plane micro-nano structure reflecting mirror, and the method can comprise the steps: carrying out the lightweight machining of an initial mirror blank, and obtaining a lightweight mirror blank; a flexible joint supporting unit is additionally arranged on the non-optical face of the light-weight mirror blank, and a mirror blank assembly is formed; and the plane optical surface of the mirror blank assembly is processed to form a micro-nano structure, and the plane micro-nano structure reflector is obtained. By means of the machining method, the machining precision and stability of the light-weight plane micro-nano structure reflector can be improved, and the possibility that the reflector deforms during machining and using is reduced.

Description

Technical Field

[0001] The present application relates to the field of micro-nano processing technology. Specifically, it relates to a method for manufacturing a planar micro-nano structure mirror and a planar micro-nano structure mirror. Background Art

[0002] Traditional mirrors with curved configurations have problems such as low design freedom, heavy structures, and complex systems, making it difficult to meet the requirements for lightweight mirrors.

[0003] Different from traditional mirrors, micro-nano structure mirrors modulate light waves through the micro-nano structures on their surfaces. Such micro-nano structure mirrors can meet the requirement of lightweight. However, after the lightweight treatment of the mirror blank, its rigidity will be significantly reduced. Therefore, during the process of processing the micro-nano structures on the surface of the mirror blank, its surface shape is extremely likely to change. Summary of the Invention

[0004] The purpose of the present application is to provide a method for manufacturing a planar micro-nano structure mirror and a planar micro-nano structure mirror, which can improve the processing accuracy and stability of lightweight micro-nano structure mirrors, improve the performance of the mirrors, and reduce the deformation amount during their processing and use.

[0005] In a first aspect, the present invention provides a method for manufacturing a planar micro-nano structure mirror, including: performing lightweight processing on an initial mirror blank to obtain a lightweight mirror blank; installing a flexible joint support unit on the non-optical surface of the lightweight mirror blank to form a mirror blank assembly; processing the planar optical surface of the mirror blank assembly to form micro-nano structures, thereby obtaining a planar micro-nano structure mirror.

[0006] In the above implementation, in the method for manufacturing a lightweight planar micro-nano structure mirror, installing a flexible joint support unit on the mirror blank after lightweight processing can provide support for the mirror blank during the processing, so that even after the lightweight treatment of the mirror blank, the mirror blank is not easily deformed in surface shape. Further, during the entire processing process, the flexible joint support unit and the mirror blank are always processed integrally, avoiding the uncertain change in the surface shape of the mirror blank caused by the disassembly and assembly of the flexible joint, and enabling the processed mirror to have higher accuracy.

[0007] In an alternative embodiment, the processing the planar optical surface of the mirror blank assembly to form micro-nano structures to obtain a planar micro-nano structure mirror includes: polishing the planar optical surface of the mirror blank assembly to make the surface shape of the planar optical surface reach a preset threshold; processing the planar optical surface of the polished mirror blank assembly to form micro-nano structures to obtain an initial micro-nano structure mirror; plating a reflective film on the surface where the micro-nano structures of the initial micro-nano structure mirror are located to obtain a planar micro-nano structure mirror.

[0008] In an alternative embodiment, processing the planar optical surface of the polished mirror blank assembly to form a micro-nano structure to obtain an initial micro-nano structure mirror includes: coating a photoresist on the planar optical surface of the polished mirror blank assembly; forming a photoresist pattern on the photoresist by exposure and development; etching with the photoresist pattern as a masking layer to form a micro-nano structure, thereby obtaining an initial micro-nano structure mirror.

[0009] In an alternative embodiment, processing the planar optical surface of the polished mirror blank assembly to form a micro-nano structure to obtain an initial micro-nano structure mirror includes: forming a micro-nano structure having one or more of a single-layer step, a multi-layer step, and a continuous surface structure on the planar optical surface of the polished mirror blank assembly, thereby obtaining an initial micro-nano structure mirror.

[0010] In an alternative embodiment, the preset threshold includes a first preset threshold and a second preset threshold; polishing the planar optical surface of the mirror blank assembly to make the surface shape of the planar optical surface reach the preset threshold includes: performing primary polishing on the planar optical surface to make the surface shape of the planar optical surface of the mirror blank assembly reach the first preset threshold; performing secondary polishing on the planar optical surface to make the surface shape of the planar optical surface of the mirror blank assembly reach the second preset threshold; wherein the surface shape requirement represented by the second preset threshold is higher than the surface shape requirement represented by the first preset threshold.

[0011] In the above implementation, polishing of the planar optical surface can be achieved through two levels of polishing means. Based on the first-level polishing, after the surface shape of the optical surface quickly approaches the target state, secondary polishing can be carried out, enabling fine processing of the optical surface to better meet the surface shape requirements. Through the above implementation, under the condition of meeting the accuracy requirements, the processing of the surface shape can also be achieved more quickly.

[0012] In an alternative embodiment, performing secondary polishing on the planar optical surface includes: using magnetorheological polishing to perform secondary polishing on the planar optical surface.

[0013] In the above implementation, magnetorheological polishing can be used for secondary polishing, thereby enabling more refined polishing, making the surface shape of the obtained planar optical surface better meet the surface shape requirements, and thus making the accuracy of the obtained surface shape higher.

[0014] In an alternative embodiment, performing lightweight processing on the initial mirror blank to obtain a lightweight mirror blank includes: forming one or more blind holes with a set shape on the non-optical surface of the initial mirror blank; wherein the blind holes include mounting holes for installing a flexible joint support unit.

[0015] In the above implementation, forming a plurality of blind holes in the initial mirror blank can reduce the weight of the mirror and achieve a lightweight mirror. Additionally, by providing mounting holes for installing the flexible joint support unit, the relative positional relationship between the flexible joint support unit and the mirror blank during processing can be made more stable, thus enabling better support for the mirror blank.

[0016] In an alternative embodiment, the flexible joint support unit includes a flexible joint and a support plate. One end of the flexible joint is connected to the initial mirror blank through the mounting hole, and the other end of the flexible joint is fixed to the support plate; alternatively, the flexible joint support unit includes a connecting component, a flexible joint, and a support plate; the connecting component is disposed in the mounting hole and is used to connect to the initial mirror blank and one end of the flexible joint, and the other end of the flexible joint is fixed to the support plate.

[0017] In the above implementation, during the processing, the support for the mirror blank can be achieved in cooperation with the flexible joint support unit. The flexible joint support unit includes a connecting component, a flexible joint, and a support plate. More uniform support is achieved through the support plate, local support is achieved through the flexible joint, and a more stable connection is achieved through the connecting component, enabling better support for the mirror blank.

[0018] In a second aspect, the present invention provides a planar micro-nano structure mirror, which is a planar micro-nano structure mirror processed by the method according to any one of the foregoing embodiments.

[0019] In an alternative embodiment, a micro-nano structure is provided on the planar optical surface of the planar micro-nano structure mirror, and the micro-nano structure includes one or more of a single-layer step, a multi-layer step, and a continuous surface structure micro-nano structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] To more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of the present application and should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0021] Figure 1 It is a flowchart of the method for processing a planar micro-nano structure mirror provided by an embodiment of the present application;

[0022] Figure 2 It is a schematic diagram of the lightweight mirror blank structure obtained by the method for processing a planar micro-nano structure mirror provided by an embodiment of the present application;

[0023] Figure 3 It is an alternative flowchart of step 130 of the method for processing a planar micro-nano structure mirror provided by an embodiment of the present application;

[0024] Figure 4a Schematic diagram of the flexible joint support unit used in the processing method of the planar micro-nano structure mirror provided by the embodiment of the present application;

[0025] Figure 4b Schematic diagram of the structure of the flexible joint of the flexible joint support unit used in the processing method of the planar micro-nano structure mirror provided by the embodiment of the present application;

[0026] Figures 5a to 5i Schematic diagram of the semi-finished mirror during the processing method of the micro-nano structure mirror provided by the embodiment of the present application.

[0027] Icon: 210 - Initial mirror blank; 220 - Lightweight mirror blank; 221 - Blind hole; 222 - Mounting hole; 230 - Mirror blank assembly; 231 - Flexible joint support unit; 2311 - Connecting component; 2312 - Flexible joint; 2313 - Support plate; 241 - Planar optical surface; 251 - Photoresist; 252 - Photoresist pattern; 261 - Micro-nano structure; 262 - Reflective film. Detailed implementation manners

[0028] Next, the technical solutions in the embodiments of the present application will be described with reference to the accompanying drawings in the embodiments of the present application.

[0029] It should be noted that: Similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. At the same time, in the description of the present application, the terms "first", "second", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0030] As an important optical element, mirrors are widely used in laser systems, astronomical telescopes, and solar energy devices. Traditional mirrors with curved configurations usually deflect and converge the light beam propagation direction by bending the reflective surface. The mirrors formed in this way have problems such as low design freedom, heavy structure, and complex system, and it is difficult to meet the requirements of the lightweight, integration, and large aperture development of mirrors.

[0031] Due to the above problems of traditional mirrors, in recent years, micro-nano structure mirrors have received extensive attention from researchers. Compared with traditional mirrors, micro-nano structure mirrors modulate light waves through the micro-nano structures on their surfaces, and thus do not need to deflect and converge the light beam propagation direction through the existing curved reflective surface. The mirrors realized in this way can be planarized and lightweight, providing a new research direction for the development of large aperture optical systems.

[0032] During the processing of a planar micro-nano structure mirror, although the requirement of weight reduction is achieved, the rigidity of the mirror blank after weight reduction treatment will be significantly reduced, resulting in a decrease in the surface shape retention ability of the mirror blank, and leading to an extremely easy change in the surface shape of the planar optical surface during the micro-nano structure processing and assembly use of the planar optical surface of the mirror blank, thereby resulting in a decline in the optical performance of the mirror or even failing to meet the usage requirements of the mirror.

[0033] Based on the above research, an embodiment of the present application can provide a method for processing a planar micro-nano structure mirror and a planar micro-nano structure mirror, which can improve the rigidity during the mirror processing and improve the stability of the mirror. The following describes the method for processing a planar micro-nano structure mirror and a planar micro-nano structure mirror provided by the present application in combination with some embodiments.

[0034] Please refer to Figure 1 , Figure 1 which is a flowchart of the method for processing a planar micro-nano structure mirror provided by an embodiment of the present application. The method for processing a planar micro-nano structure mirror provided by an embodiment of the present application can be applied to a mirror processing system, and the steps in the method for processing a planar micro-nano structure mirror are executed through this mirror processing system. The following will elaborate in detail on the Figure 1 specific process shown.

[0035] Step 110, perform weight reduction processing on the initial mirror blank to obtain a weight-reduced mirror blank.

[0036] Through the processing of step 110 above, a weight-reduced mirror blank lighter than the initial mirror blank can be obtained (as shown in Figure 5b ). Among them, the weight reduction processing method can include thinning the initial mirror blank and forming weight reduction holes on the non-optical surface of the initial mirror blank, etc.

[0037] Optionally, the weight reduction processing of the initial mirror blank 210 is achieved by cutting weight reduction holes on the initial mirror blank 210. One or more weight reduction holes can be formed on the initial mirror blank 210. The weight reduction hole can be a blind hole 221 that does not penetrate the initial mirror blank 210.

[0038] Exemplarily, the shape of the weight reduction hole can be arbitrary. For example, the shape of the weight reduction hole can be one or more of the shapes such as triangle, rectangle, honeycomb, circle, sector, etc. Optionally, multiple different-shaped weight reduction holes can be formed on the initial mirror blank 210, or multiple weight reduction holes with the same shape can be formed on the initial mirror blank 210. Each weight reduction hole can be evenly distributed on the non-optical surface of the initial mirror blank 210, or each weight reduction hole can be unevenly distributed on the non-optical surface of the initial mirror blank 210.

[0039] In Figure 2Triangular and circular weight-reducing holes are formed in the lightweight mirror blank 220 shown. The weight-reducing holes in this example are blind holes 221. It can be understood that Figure 2 The lightweight mirror blank shown is hexagonal. In actual processing, the mirror blank can also be in other shapes, such as circular.

[0040] Optionally, before performing lightweight processing, the amount of weight reduction to be achieved can be determined first. This amount of weight reduction can be expressed in terms of weight or volume. After determining the amount of weight reduction, lightweight processing can be carried out on the initial mirror blank 210 according to the amount of weight reduction.

[0041] In some cases, the shape of the original mirror blank differs significantly from the shape of the reflector to be processed and formed. Based on this situation, before performing step 110, it may also include machining the shape of the original mirror blank so that the shape of the obtained mirror blank can be approximated to the shape of the reflector to be processed and formed. Exemplarily, a milling and forming method can be used to machine the shape of the original mirror blank to obtain the initial mirror blank 210 that needs to be processed in step 110. For example, a processing drawing of the shape of the reflector to be processed and formed can be pre-drawn, and based on this processing drawing, the shape of the original mirror blank can be machined to obtain an initial mirror structure that meets the requirements.

[0042] Step 120, installing a flexible joint support unit on the non-optical surface of the lightweight mirror blank to form a mirror blank assembly.

[0043] Optionally, the flexible joint support unit 231 (see Figure 4a and Figure 4b shown) can include materials with a buffering effect. Exemplarily, only part of the flexible joint support unit 231 can have materials with a buffering effect; the flexible joint support unit 231 can be entirely made of materials with a buffering effect.

[0044] Optionally, the flexible joint support unit 231 can be installed on the non-optical surface of the lightweight mirror blank 220 by adhesion.

[0045] Step 130, machining the planar optical surface of the mirror blank assembly to form a micro-nano structure to obtain a planar micro-nano structure reflector.

[0046] Based on different actual requirements, the micro-nano structure 261 to be processed and formed may also be different. Figure 5hIn the illustrated example, the micro-nano structure 261 is a single-layer stepped structure. Exemplarily, the micro-nano structure 261 can be determined based on parameters such as the focal length, F-number, and operating wavelength of the mirror. In some examples, the micro-nano structure 261 can be a multi-layer stepped structure, a continuous surface structure, a single-layer stepped structure, etc. The micro-nano structure 261 can also be a combination of two or three of the single-layer stepped structure, the multi-layer stepped structure, and the continuous surface structure. In actual processing, based on different parameter requirements of the planar micro-nano structure mirror actually needed, the micro-nano structure 261 can also be adaptively designed into different structures.

[0047] In this embodiment, the optical surface of the mirror blank assembly 230 is planar.

[0048] Optionally, the compliant support unit 231 can remain connected to the mirror blank during the processing of obtaining the planar micro-nano structure mirror after installation.

[0049] Optionally, the compliant support unit 231 can remain connected to the mirror blank during the processing of obtaining the planar micro-nano structure mirror after installation, and also remain connected to the mirror blank during the assembly process of the planar micro-nano structure mirror.

[0050] In the planar micro-nano structure mirror provided by the embodiment of the present application, the optical surface forms different reflection requirements through the action of some micro-nano structures, without the need to form a curved surface on the optical surface of the overall mirror blank.

[0051] Through the above method, in the processing method of the lightweight planar micro-nano structure mirror, by adding the compliant support unit 231 to the mirror blank after lightweight processing, support can be provided for the mirror blank, so that even after the mirror blank has been lightweight processed, the mirror blank is not easily deformed. Further, it is possible to achieve that the mirror blank is not easily deformed due to the stress generated during processing during the processing of the mirror, improve the stability during the processing, and also enable the accuracy of the processed mirror to be higher.

[0052] During the process of forming the planar micro-nano structure mirror, in order to make the accuracy of the mirror higher, some other treatments can also be performed. Based on this, as Figure 3 shown, the above step 130 can include steps 131 to 133.

[0053] Step 131, polishing the planar optical surface of the mirror blank assembly to make the surface shape of the planar optical surface reach a preset threshold.

[0054] Optionally, the planar optical surface of the mirror blank assembly 230 can be polished using a grinding and polishing method.

[0055] Optionally, the method of magnetorheological polishing can be adopted to polish the planar optical surface of the mirror blank assembly 230.

[0056] Optionally, the preset threshold can be set based on the requirements of the actual mirror. The preset threshold can be used to define the threshold of the surface shape, and can be used to represent the undulation degree of the surface shape. The preset threshold can also be used to represent the error between the processed surface shape and the surface shape in the target state. The surface shape in the target state can be the surface shape set according to the requirements of the actual planar micro-nano structure mirror, and the parameters of the surface shape in the target state can be set in advance according to the requirements of the mirror. For example, flatness, surface shape amplitude, surface shape roughness, etc. In one example, the preset threshold can be expressed as the root mean square error (RMS) of the surface shape, and the surface shape quality of the polished planar optical surface is described by this preset threshold. For example, the preset threshold can be RMS: 1 / 50λ.

[0057] Step 132: Process the planar optical surface of the polished mirror blank assembly to form a micro-nano structure, and obtain an initial micro-nano structure mirror.

[0058] Optionally, a micro-nano structure 261 with a multi-layer stepped structure is formed on the planar optical surface of the polished mirror blank assembly 230, so as to obtain an initial micro-nano structure 261 mirror.

[0059] Step 133: Deposit a reflective film on the surface where the micro-nano structure of the initial micro-nano structure mirror is located to obtain a planar micro-nano structure mirror.

[0060] In this embodiment, a reflective film 262 is deposited on the planar optical surface of the initial micro-nano structure 261 mirror after the processing of the micro-nano structure 261 is completed (see Figure 5i shown).

[0061] Optionally, a reflective film 262 is deposited on the surface where the micro-nano structure 261 of the initial micro-nano structure 261 mirror is located based on requirements such as the reflection band and reflectivity. Among them, the working band and reflectivity are input parameters determined before designing the mirror. It can be understood that the determination of the working band and reflectivity is a pre-work and has been determined before the processing process.

[0062] The reflective film 262 can be a metal reflective film 262 or a dielectric reflective film 262. After completing step 133, the reflection wavefront, diffraction efficiency, focal length and other indicators of the obtained planar micro-nano structure mirror are detected to determine whether the obtained planar micro-nano structure mirror meets the set requirements. The set requirements can be the standard for processing the mirror determined before designing the mirror.

[0063] Through the above logic, before processing the micro-nano structure 261, the planar optical surface can also be polished first. When the surface shape of the planar optical surface meets the requirements first, and then the micro-nano structure 261 is processed, the obtained planar micro-nano structure mirror can more accurately meet the design requirements.

[0064] The above step 132 may further include steps 1321 to 1323.

[0065] Step 1321, applying a photoresist on the planar optical surface of the polished mirror blank assembly.

[0066] Exemplarily, the planar optical surface is cleaned before applying the photoresist 251, and the planar optical surface coated with the photoresist 251 is baked after applying the photoresist 251, so that the photoresist 251 can adhere more firmly to the planar optical surface. Refer to Figure 5f the mirror blank assembly obtained by applying the photoresist 251 as shown.

[0067] Optionally, the photoresist 251 can be applied by spin coating or by doctor blading.

[0068] Considering that the high-speed rotation centrifugal force formed by the spin coating method may affect the flexible joint support unit 231, a glue application support unit can be provided for the polished mirror blank assembly 230 to reduce the possible adverse effects of the high-speed rotation centrifugal force on the flexible joint support unit 231. The glue application support unit may include a base and a support module mounted on the base. The support module may include two support parts, and the two support parts are distributed on both sides of the polished mirror blank assembly 230. By providing support forces through the relatively fixed support parts on both sides, the centrifugal force generated during the high-speed rotation can be offset, playing a protective role for the flexible joint support unit 231.

[0069] In one example, the photoresist type of the photoresist 251 can be selected as AZ1500, and the coating thickness is 500 nm. After the photoresist 251 is coated, it is placed in an oven for baking. The baking parameters of the oven can be: baking temperature 100 °C, baking duration 10 minutes. It can be understood that the baking parameters are only the parameters selected for this example. In the case of different photoresist types and different coating thicknesses of the actually coated photoresist 251, the baking parameters may also be different. For example, when the coating thickness is thicker, the baking temperature can be higher, or the baking duration can be longer. For another example, when the photoresist type of the selected photoresist 251 is a more difficult-to-set photoresist, the baking temperature can be higher, or the baking duration can be longer.

[0070] Step 1322, forming a photoresist pattern on the photoresist through exposure and development.

[0071] Optionally, the photoresist 251 can be exposed according to a pre-designed image, and then the exposed photoresist 251 is developed to form a photoresist pattern 252 (see Figure 5g shown).

[0072] The exposure method can be laser direct writing technology, projection exposure, contact exposure and other exposure methods. The development method can be wet development.

[0073] In this embodiment, ordinary direct writing or overlay can be performed based on the number of layers of the required micro-nano structure 261. For example, if the number of layers of the required micro-nano structure 261 is a single layer, ordinary direct writing can be used for exposure; if the number of layers of the required micro-nano structure 261 is multiple layers, overlay can be used for exposure.

[0074] In this embodiment, inverted development can be used during the development of the photoresist pattern 252, and the flexible support unit 231 may not be in direct contact with the developer. Exemplarily, during inverted development, the planar optical surface of the mirror blank assembly 230 can be immersed in the developer, and the flexible support unit is not in direct contact with the developer. Exemplarily, the development time can be 0.5 - 1.5 minutes. For example, the development time can be 0.5 minutes, 1 minute, 1.5 minutes, etc. This development time can be determined based on the photoresist pattern 252 to be developed.

[0075] Step 1323, etching is performed using the photoresist pattern as a mask layer to form a micro-nano structure, and an initial micro-nano structure mirror is obtained.

[0076] Optionally, a dry etching technique can be used to pattern the photoresist 252 on the planar optical surface of the polished mirror blank assembly 230, thereby forming a micro-nano structure 261 on the planar optical surface.

[0077] In one example, the etching depth of a single step of the micro-nano structure 261 of the planar micro-nano structure mirror to be formed is 320 nm, and the total depth is 3 × 320 nm. Of course, this example is only exemplary, and based on different actual requirements, the step etching depth and total depth of the micro-nano structure 261 can also be other values.

[0078] Through the above implementation logic, a pattern can be first formed in the photoresist 251, and then the micro-nano structure 261 is etched based on the photoresist pattern 252, which can make the etched micro-nano structure 261 more accurate and better meet the design requirements of the planar micro-nano structure mirror.

[0079] In different situations, the surface profile undulation of the planar optical surface of the mirror blank assembly 230 may vary, which also leads to different amounts of polishing required. When the amount to be removed by polishing is larger, the time required for polishing may be longer. To improve the efficiency of surface profile polishing of the planar optical surface of the mirror blank assembly 230. Based on this, the above step 131 may include step 1311 and step 1312.

[0080] The above preset thresholds may include a first preset threshold and a second preset threshold. Among them, the surface profile requirement represented by the second preset threshold is higher than that represented by the first preset threshold. In this embodiment, the surface profile represented by the second preset threshold is closer to the shape of the optical surface of the pre-designed planar micro-nano structure mirror than the surface profile represented by the first preset threshold. For example, in the case where a planar optical surface needs to be obtained through polishing, the surface profile represented by the second preset threshold has smaller undulations than the surface profile represented by the first preset threshold.

[0081] Step 1311, perform primary polishing on the planar optical surface to make the surface profile of the planar optical surface of the mirror blank assembly reach the first preset threshold.

[0082] Refer to Figure 5d As shown, this primary polishing can be rough polishing, and through this primary polishing, the surface profile of the planar optical surface can be quickly approximated to a plane. Exemplarily, the first preset threshold can be greater than the RMS value corresponding to the surface profile required for the planar optical surface. For example, if the preset required surface profile of the planar optical surface is not greater than RMS: 1 / 50λ. Then the first preset threshold is a value greater than RMS: 1 / 50λ. For example, the first preset threshold can be RMS: 1 / 2λ.

[0083] Optionally, this primary polishing can be abrasive polishing method, ring polishing method, etc.

[0084] Step 1312, perform secondary polishing on the planar optical surface to make the surface profile of the planar optical surface of the mirror blank assembly reach the second preset threshold.

[0085] Refer to Figure 5e As shown, this secondary polishing can be fine polishing, and through this secondary polishing, the surface profile of the planar optical surface can be more accurately formed into the required surface profile of the planar optical surface. The second preset threshold can be not greater than the RMS value corresponding to the surface profile required for the planar optical surface. For example, if the preset required surface profile of the planar optical surface is not greater than RMS: 1 / 50λ. Then the second preset threshold is a value not greater than RMS: 1 / 50λ. For example, the second preset threshold can be equal to RMS: 1 / 50λ. The second preset threshold can also be a value smaller than RMS: 1 / 50λ. Of course, based on different actual requirements for the surface profile of the planar optical surface, the second preset threshold can also be a larger or smaller value.

[0086] Optionally, the secondary polishing can be magnetorheological polishing.

[0087] In the above implementation, the surface shape of the planar optical surface can be processed to a certain accuracy by the primary polishing first, so as to reduce the processing amount of the surface shape fine polishing of the planar optical surface during the centering of the secondary polishing, and improve the polishing efficiency.

[0088] In one implementation, step 110 above can include forming one or more blind holes 221 with a set shape on the non-optical surface of the initial mirror blank 210.

[0089] Among them, the blind hole 221 includes a mounting hole 222 for mounting the flexure support unit 231.

[0090] The shape of the mounting hole 222 can be the same as the shape of other blind holes 221 formed on the non-optical surface of the initial mirror blank 210, or can be different from the shape of other blind holes 221 formed on the non-optical surface of the initial mirror blank 210.

[0091] The shape of the mounting hole 222 can fit the shape of the part of the flexure support unit 231 used to connect with the mounting hole 222. The size of the mounting hole 222 can also be larger than the size of the part of the flexure support unit 231 used to connect with the mounting hole 222 to facilitate the installation of the flexure support unit 231 on the lightweight mirror blank 220.

[0092] Optionally, the flexure support unit 231 includes a flexure 2312 and a support plate 2313; one end of the flexure 2312 is connected to the initial mirror blank 210 through a mounting hole, and the other end of the flexure 2312 is fixed on the support plate 2313.

[0093] When the lightweight mirror blank 220 is formed with a mounting hole 222 for mounting the flexure support unit 231, the flexure 2312 can be installed in the mounting hole 222 formed on the non-optical surface of the lightweight mirror blank 220.

[0094] In this example, the size of the mounting hole 222 of the lightweight mirror blank 220 can be larger than that of the flexure 2312 to facilitate the installation of the flexure 2312 in the mounting hole 222. The shape of the mounting hole 222 of the lightweight mirror blank 220 can fit the shape of the flexure 2312 to facilitate the installation of the flexure 2312 in the mounting hole 222.

[0095] Exemplarily, the flexure 2312 can be connected and installed to the lightweight mirror blank 220 by an adhesive method.

[0096] To facilitate the connection with the lightweight mirror blank 220, the flexible joint support unit 231 may also be designed with a connecting component 2311 for connecting to the non-optical surface of the lightweight mirror blank 220. One end of the connecting component 2311 can be used to connect to the non-optical surface of the lightweight mirror blank 220, and the other end of the connecting component 2311 can be connected to the flexible joint.

[0097] Optionally, as Figure 4a and Figure 4b shown, the flexible joint support unit 231 includes a connecting component 2311, a flexible joint 2312, and a support plate 2313; the connecting component 2311 is disposed in the mounting hole and is used to connect to the initial mirror blank 210, and the connecting component 2311 can also be connected to one end of the flexible joint 2312, and the other end of the flexible joint 2312 is fixed on the support plate 2313. Among them, as Figure 4a and Figure 4b are schematic diagrams of different perspectives and different states, and the example shown in Figure 4a is a plan schematic diagram of the flexible joint support unit 231, Figure 4b is a three-dimensional schematic diagram of the flexible joint 2312.

[0098] Exemplarily, one end of the flexible joint 2312 is connected to the connecting component 2311, and the other end of the flexible joint 2312 is fixed on the support plate 2313.

[0099] When the lightweight mirror blank 220 is formed with a mounting hole 222 for mounting the flexible joint support unit 231, the connecting component 2311 can be connected within the mounting hole 222 of the lightweight mirror blank 220.

[0100] In this example, the size of the mounting hole 222 of the lightweight mirror blank 220 can be larger than that of the connecting component 2311 to facilitate the installation of the connecting component 2311 within the mounting hole 222. The shape of the mounting hole 222 of the lightweight mirror blank 220 can fit the shape of the connecting component 2311 to facilitate the installation of the connecting component 2311 within the mounting hole 222.

[0101] Optionally, Figure 4b in the example shown, the connecting component 2311 can be a tapered sleeve. The connecting component 2311 can be connected and installed with the lightweight mirror blank 220 by an adhesive method. The material of the tapered sleeve can be selected to be a material with a thermal expansion coefficient close to that of the mirror blank. The tapered sleeve can be connected to the flexible joint 2312 by a connecting member such as a screw. The other end of the flexible joint 2312 and the support plate 2313 are fixed by screws again.

[0102] Optionally, the material of the flexible joint 2312 can be invar. Exemplarily, the flexible structure of the flexible joint 2312 can be a three-leaf type, and the three groups of flexible structures can be evenly distributed on the support plate 2313. Exemplarily, they can be evenly distributed on the support plate 2313 in a circumferential manner.

[0103] To better provide a buffering effect, the flexible joint 2312 can be provided with axial and radial flexible grooves for buffering the stresses generated by temperature and assembly.

[0104] Optionally, the material of the support plate 2313 can also be invar.

[0105] The flexible joint 2312 can be a component with a buffering effect in the flexible joint support unit 231. The support plate 2313 can be a component that relatively fixes the mirror blank during the processing.

[0106] Through the buffering effect of the flexible joint 2312, the stresses generated during the processing and assembly processes and the influence of temperature changes on the surface shape of the mirror blank can be buffered, enabling the mirror blank to achieve higher precision during the surface shape processing. At the same time, when micro-nano structures 261 are processed on the planar optical surface of the mirror blank, the obvious change in the surface shape of the mirror blank caused by the complex thermodynamic environment in the processing process of the micro-nano structures 261 can be reduced.

[0107] Next, a complete processing flow of the lens will be described in combination with an example and a schematic diagram of the mirror blank obtained during the processing. Figures 5a to 5i Schematic diagrams of semi-finished mirrors during the processing of the mirror are respectively shown. In Figures 5a to 5i the upper and lower surfaces of the mirror blank, a relatively large processing range is exaggeratedly shown. It can be understood that in actual processing, the changes in the upper and lower surfaces of the mirror blank may be relatively small.

[0108] First, the original mirror blank can be milled and formed to process the outer shape of the original mirror blank, obtaining Figure 5a the initial mirror blank 210 shown.

[0109] Then, the initial mirror blank 210 of Figure 5a is subjected to the lightweight processing of step 110 to obtain Figure 5b the lightweight mirror blank 220 shown. Among them, Figure 5b in the example shown, blind holes 221 formed on the non-optical surface are shown, and mounting holes 222 for installing the flexible joint support unit 231 are included in the blind holes 221.

[0110] After obtaining the lightweight mirror blank 220, the flexible joint support unit 231 can be installed using step 120 to form Figure 5c the mirror blank assembly 230 shown.

[0111] Then, the primary polishing of step 1311 and the secondary polishing of step 1312 are used to obtain Figure 5d and Figure 5e plane optical surfaces with different surface shapes. From Figure 5d and Figure 5eAs can be seen from the illustrated examples, the undulation of the planar optical surface obtained by primary polishing is greater than that of the planar optical surface 241 obtained by secondary polishing.

[0112] By using step 1321 to coat a photoresist 251 on the planar optical surface, the Figure 5f illustrated mirror blank assembly 230 is obtained. By using step 1322 to form a photoresist pattern 252 on the photoresist 251, the Figure 5g illustrated mirror blank assembly 230 is obtained. By using step 1323 to form a micro-nano structure 261 on the planar optical surface, the Figure 5h illustrated initial micro-nano structure mirror is obtained.

[0113] Finally, by using step 133 to deposit a reflective film 262 on the surface where the micro-nano structure 261 is located, the Figure 5i illustrated planar micro-nano structure mirror is obtained.

[0114] An embodiment of the present application also provides a planar micro-nano structure mirror, which is processed by using the above method.

[0115] In this embodiment, a micro-nano structure 261 is provided on the planar optical surface of the planar micro-nano structure mirror, and the micro-nano structure 261 includes one or more of a single-layer step, a multi-layer step, and a continuous surface structure.

[0116] In Figure 5h the illustrated example, the micro-nano structure 261 is a single-layer structure. Based on different actual reflection requirements, the formed micro-nano structure can be different from the Figure 5h illustrated example.

[0117] For other details of the planar micro-nano structure mirror provided by the embodiment of the present application, reference can be made to the description in the embodiment of the processing method of the planar micro-nano structure mirror described above, and details will not be elaborated here.

[0118] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application. It should be noted that similar reference numerals and letters indicate similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0119] As described above, it is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should all be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A method for processing a planar micro-nanostructure reflector, characterized in that: include: Performing lightweight processing on the initial mirror blank to obtain a lightweight mirror blank; Adding a flexible support unit to the non-optical surface of the lightweight mirror blank to form a mirror blank assembly; The planar optical surface of the mirror blank assembly is processed to form a micro-nano structure to obtain a planar micro-nano structure reflector.

2. The method according to claim 1, characterized in that The process of processing the planar optical surface of the mirror blank component to form a micro-nano structure to obtain a planar micro-nano structure reflector comprises: Polishing the planar optical surface of the mirror blank assembly so that the surface shape of the planar optical surface reaches a preset threshold; Processing the polished plane optical surface of the mirror blank assembly to form a micro-nano structure to obtain an initial micro-nano structure reflector; A reflective film is plated on the surface where the micro-nano structure of the initial micro-nano structure reflector is located to obtain a planar micro-nano structure reflector.

3. The method according to claim 2, characterized in that The process of processing the polished planar optical surface of the mirror blank assembly to form a micro-nano structure to obtain an initial micro-nano structure reflector comprises: Coating photoresist on the polished planar optical surface of the mirror blank assembly; forming a photoresist pattern on the photoresist by exposure and development; The photoresist pattern is used as a masking layer for etching to form a micro-nano structure, thereby obtaining an initial micro-nano structure reflector.

4. The method according to claim 3, characterized in that The process of processing the polished planar optical surface of the mirror blank assembly to form a micro-nano structure to obtain an initial micro-nano structure reflector comprises: A micro-nano structure having one or more of a single-layer step, a multi-layer step, and a continuous surface structure is formed on the plane optical surface of the mirror blank component after polishing to obtain an initial micro-nano structure reflector.

5. The method according to claim 2, characterized in that: in, The preset threshold includes a first preset threshold and a second preset threshold; The step of polishing the planar optical surface of the mirror blank assembly so that the surface shape of the planar optical surface reaches a preset threshold value comprises: Performing primary polishing on the planar optical surface so that the surface shape of the planar optical surface of the mirror blank assembly reaches a first preset threshold; Performing secondary polishing on the planar optical surface so that the surface shape of the planar optical surface of the mirror blank assembly reaches a second preset threshold; The face shape requirement represented by the second preset threshold is higher than the face shape requirement represented by the first preset threshold.

6. The method according to claim 5, characterized in that The step of performing secondary polishing on the planar optical surface comprises: The plane optical surface is subjected to secondary polishing by adopting a magnetorheological polishing method.

7. The method according to claim 1, characterized in that The lightweight processing of the initial mirror blank to obtain the lightweight mirror blank comprises: One or more blind holes of a set shape are formed on the non-optical surface of the initial mirror blank; wherein the blind holes include mounting holes for mounting a flexible support unit.

8. The method according to claim 7, characterized in that The flexible joint support unit comprises a flexible joint and a support plate, one end of the flexible joint is connected to the initial mirror blank through a mounting hole, and the other end of the flexible joint is fixed on the support plate; or, The flexible joint support unit includes a connecting component, a flexible joint and a support plate; the connecting component is arranged in the mounting hole and is used to connect with the initial mirror blank and one end of the flexible joint, and the other end of the flexible joint is fixedly mounted on the support plate.

9. A planar micro-nanostructure reflector, characterized in that: A planar micro-nanostructure reflector manufactured using the method described in any one of claims 1 to 8.

10. The planar micro-nanostructure reflector according to claim 9, characterized in that: A micro-nano structure is arranged on the planar optical surface of the planar micro-nano structure reflector, and the micro-nano structure includes one or more micro-nano structures selected from the group consisting of single-layer steps, multi-layer steps, and continuous surface structures.

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