A high-precision, high-curvature focusing lens and its processing method

Abstract

This invention relates to a focusing lens and its processing method, particularly to a high-precision, large-curvature focusing lens and its processing method, solving the problems of low imaging stability during focusing in existing imaging equipment and low processing accuracy when processing spherical surfaces with large curvature radii using existing methods. The processing method is characterized by the following steps: Step 1: Selecting a glass substrate; Step 2: Fixing the substrate using an optical adhesive mounting method; polishing both surfaces of the substrate to achieve an RMS value better than 0.02λ; Step 3: Fabricating a fixture and installing it onto the substrate, using the fixture to completely block the area on the surface to be processed except for the area to be processed by the ion beam equipment in the next step; Step 4: Processing the exposed areas with the ion beam equipment, using an interferometer to detect the POWER value during processing to control the radius of curvature; once the radius of curvature meets the requirements, the ion beam equipment stops, and the fixture is removed; Step 5: Repeating steps 3 and 4 until all spherical areas are processed.

Description

Technical Field

[0001] This invention relates to a focusing lens and its processing method, and particularly to a high-precision, high-curvature focusing lens and its processing method. Background Technology

[0002] Most existing focusing lenses use resin or liquid lenses, which have relatively low precision and are widely used in the civilian industry. In the aerospace field, high lens precision is required, and lens materials are all glass. To achieve focusing functionality, lenses typically rely on moving components, which significantly reduces the stability of the imaging equipment.

[0003] On the other hand, in existing processing technologies, when processing spherical surfaces with a curvature radius of less than 2m, a ring-type sphere gauge is used to make a standard template to measure the curvature radius of the spherical surface being processed, with a measurement accuracy higher than 0.001mm. However, for processing spherical surfaces with a curvature radius of 20m to 100m, there is no practical processing method in existing processing technologies. If a ring-type sphere gauge is still used to make a standard template to measure the curvature radius of the spherical surface being processed, the measurement error is usually 1% to 5%, resulting in lower precision of the processed lens, which is difficult to meet the high precision requirements of the aerospace field, i.e., the error is usually required to be controlled within 1%. Summary of the Invention

[0004] The purpose of this invention is to provide a high-precision, large-curvature focusing lens and its processing method, in order to solve the technical problems of low imaging stability in existing focusing imaging devices used in the aerospace field, and low processing accuracy when processing large-curvature radius spherical surfaces using existing processing methods, which makes it difficult to meet the high-precision requirements of lenses in the aerospace field.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A high-precision, high-curvature focusing lens, its special feature is:

[0007] Including a glass substrate with an integrated structure;

[0008] The front and back surfaces of the substrate are defined as the first surface and the second surface, respectively.

[0009] The first surface is planar;

[0010] The second surface includes multiple spherical regions, each with a different radius of curvature, and includes spherical regions with a radius of curvature greater than or equal to 20,000 mm.

[0011] Furthermore, for ease of focusing, the glass substrate is circular in shape;

[0012] The multiple spherical regions are arranged concentrically adjacent to each other from the inside out, and the radius of curvature of the spheres increases sequentially from the inside out.

[0013] The second surface also includes an annular planar region located on the outermost side of the plurality of spherical regions.

[0014] Furthermore, in order to make the effective focusing aperture of the focusing lens larger, the width of the transition region between two adjacent spherical regions and between adjacent spherical regions and planar regions, projected onto the plane containing the outer contour line of the substrate, is less than 0.1 mm along the radial direction of the substrate.

[0015] Furthermore, in order to improve the optical stability and radiation resistance of the focusing lens and better meet the application requirements in the aerospace field, the glass material is fused silica glass.

[0016] Meanwhile, this invention also provides a method for processing high-precision, high-curvature focusing lenses, which is characterized by including the following steps:

[0017] Step 1: Select a substrate with corresponding radial and thickness dimensions and made of glass, based on the radial and thickness requirements of the focusing lens to be processed;

[0018] Step 2: Fix the substrate selected in Step 1 using optical adhesive mounting; then polish the front and back surfaces of the substrate. During the polishing process, use a planar template in conjunction with an interferometer to detect the planar surface shape error, and detect the planar surface shape of the two polished surfaces to ensure that the RMS value of the planar surface shape of the two surfaces is better than 0.02λ, where λ refers to the wavelength of the standard light source on the interferometer.

[0019] Step 3: Based on the distribution and radius of curvature of the areas to be processed on the substrate surface, as well as the spherical area to be processed, a corresponding fixture is made. The fixture is designed to completely cover the area on the substrate surface except for the area to be processed by the next ion beam equipment, leaving only the area to be processed by the next ion beam equipment exposed. Then, the fixture is installed on the substrate after polishing in Step 2.

[0020] Step 4: The exposed area to be processed by the next ion beam equipment in Step 3 is processed using an ion beam device. During the processing, an interferometer is used to detect the POWER value to control the radius of curvature of the processed sphere, so as to obtain a sphere with a radius of curvature that meets the design requirements. After the radius of curvature of the processed area meets the design requirements, the ion beam equipment stops processing and the tooling is removed. The height of the spherical cap is calculated based on the radius of curvature R of the spherical area to be processed and the base circle radius r of the corresponding spherical cap. The height of the spherical cap is the sagitta H of the spherical area to be processed. Then, the sagitta H is converted into a POWER value to obtain the POWER value.

[0021] Step 5: Repeat steps 3 and 4 until all spherical areas to be processed are completed, thus obtaining the required high-precision, high-curvature focusing lens.

[0022] Furthermore, in order to prevent contamination of the ion beam equipment during processing and avoid significant economic losses, the tooling in step three is a graphite tooling.

[0023] Furthermore, in order to facilitate focusing, and to better ensure the accuracy of the final processed focusing lens, and to make the effective focusing aperture of the final processed focusing lens larger, the substrate in step one is circular in shape.

[0024] In step three, the graphite fixture is a circular bottle cap with an opening on top and flanges around the edges; the internal radial dimension of the circular bottle cap matches the radial dimension of the substrate; the position and size of the opening on the top corresponds to the area to be processed by the ion beam equipment in step three; the dimensional accuracy of the graphite fixture should meet the following conditions: the width of the projection of the transition area of ​​each adjacent area on the plane of the outer contour line of the substrate after the spherical area has been processed is less than 0.1 mm along the radial direction of the substrate.

[0025] Furthermore, in order to achieve higher precision in the final processed focusing lens, in step four, when controlling the radius of curvature of the processed sphere using the method of detecting the POWER value with an interferometer, the standard lens used in the interferometer is a planar lens, and the POWER value detection precision of the interferometer is 0.001λ to 0.01λ.

[0026] Furthermore, in order to improve the optical stability and radiation resistance of the final processed focusing lens and better meet the application requirements in the aerospace field, the glass material in step one is fused silica glass.

[0027] Step five specifically involves repeating steps three and four until all spherical areas to be processed are completed. Then, using a coating machine, an antireflective coating is deposited on the substrate after all spherical areas have been processed. The outermost layer of the antireflective coating is made of SiO2, thus obtaining the desired high-precision, high-curvature focusing lens.

[0028] Furthermore, the substrate surface to be processed in step three includes multiple concentrically arranged spherical regions to be processed, arranged from the inside out, with their radii of curvature increasing sequentially. When processing in steps three and four in a cyclical manner to complete the processing of all spherical regions to be processed, each spherical region to be processed is processed sequentially from the outside in. When processing each spherical region to be processed, the area to be processed by the next ion beam device in step three is the area within the outer contour line of the spherical region to be processed, which is close to the outer edge of the substrate.

[0029] Alternatively: Step 3 describes a substrate surface to be processed that includes multiple concentrically arranged, adjacent regions with decreasing radii of curvature from the inside out. When processing all the spherical regions in Step 3 and Step 4 in a cyclical manner, each spherical region is processed sequentially from the inside out. Furthermore, when processing each spherical region, the area to be processed by the next ion beam device in Step 3 is the region between the outermost spherical region's outer contour line near the substrate's outer edge and the inner contour line of the spherical region to be processed near the substrate's center.

[0030] The beneficial effects of this invention are:

[0031] (1) The high-precision large curvature focusing lens processing method of the present invention utilizes the characteristic of ion beam equipment to precisely process specific areas. Then, by cooperating with tooling, all areas that do not need to be processed by the ion beam equipment are completely blocked, leaving only the areas that need to be processed by the ion beam equipment exposed. During the processing, an interferometer is used to detect the POWER value to control the radius of curvature of the processed sphere. This process is repeated to complete the processing of multiple spherical areas on the same surface. The processing and detection accuracy are both very high, avoiding the low measurement accuracy of existing processing technologies that use a ring-type sphere diameter meter to make a standard template for measurement during the processing of large curvature spheres, which is difficult to meet the requirements of aviation. The aerospace field faces the challenge of high-precision lens requirements. The high-precision, large-curvature focusing lens processing method of this invention produces a single-piece focusing lens that is stable and reliable, with minimal coaxiality and eccentricity errors. Focusing is achieved by utilizing the different curvatures of different areas of the lens, eliminating the need for moving components during focusing. When used in imaging equipment, it exhibits excellent imaging stability. Therefore, this invention solves the technical problems of low imaging stability in existing focusing-enabled imaging equipment used in the aerospace field, and low processing accuracy when processing large-curvature spherical surfaces using existing methods, making it difficult to meet the high-precision lens requirements of the aerospace industry. The high-precision, large-curvature focusing lens processing method of this invention can process spherical surfaces with curvature radii of 20m to 100m, with a focusing lens error within 1%.

[0032] (2) In the processing method of the high-precision large curvature focusing lens of the present invention, the tooling is preferably graphite tooling, which can prevent the ion beam equipment from being contaminated during processing and avoid significant economic losses.

[0033] (3) In the processing method of the high-precision large curvature focusing lens of the present invention, the graphite tooling is preferably a circular bottle cap with an opening on the top and flanges around the edges. This not only facilitates the installation of the tooling and the substrate, but also achieves higher fitting accuracy, thereby better ensuring the accuracy of the final processed focusing lens. At the same time, by controlling the dimensional accuracy of the graphite tooling, the width of the projection of the transition area of ​​each adjacent area on the plane of the outer contour line of the substrate on the surface of the processed spherical area along the radial direction of the substrate is less than 0.1 mm. Thus, the effective focusing aperture of the final processed focusing lens is also larger.

[0034] (4) The processing method of the high-precision large curvature focusing lens of the present invention preferably includes the step of depositing an anti-reflective coating, and the outermost layer of the anti-reflective coating is SiO2. In this way, the optical stability and radiation resistance of the final processed focusing lens are better, which can better meet the application needs of the aerospace field. Attached Figure Description

[0035] Figure 1 This is a front view of an embodiment of the high-precision, high-curvature focusing lens of the present invention;

[0036] Figure 2 It is along Figure 1 Sectional view of the middle FF line;

[0037] Figure 3 This is a flowchart of an embodiment of the processing method for the high-precision, high-curvature focusing lens of the present invention;

[0038] Figure 4 This is a schematic diagram illustrating the calculation of the sagitta of the spherical region to be processed in the processing method of the high-precision large curvature focusing lens of the present invention.

[0039] Figure 5 It is manufactured using the high-precision, high-curvature focusing lens processing method of this invention. Figure 1 and Figure 2 The manufacturing process flow chart for the focusing lens structure shown is as follows;

[0040] Figure 6 It is manufactured using the high-precision, high-curvature focusing lens processing method of this invention. Figure 1 and Figure 2 The schematic diagram of the tooling structure is shown for focusing lenses with the structure shown, wherein:

[0041] (A) is the tooling used to modify the radius of curvature of the spherical surface in the inner region of the bottom circle of the Φd2 spherical cap;

[0042] (B) is the tooling used to modify the radius of curvature of the spherical surface in the inner region of the bottom circle of the Φd1 spherical cap;

[0043] Figure 7 It is obtained by processing the high-precision, high-curvature focusing lens using the processing method of this invention. Figure 1 and Figure 2 The diagram shows the surface profile of the focusing lens with the structure shown, wherein:

[0044] (C) is the surface diagram of the Φd1 region;

[0045] (D) is the surface diagram of the region Φd1~Φd2;

[0046] (E) is the surface pattern diagram of the Φd2~Φd3 region;

[0047] Figure 8 This is a physical image of an embodiment of the high-precision, high-curvature focusing lens of the present invention.

[0048] The labels in the diagram are explained as follows:

[0049] 1-Region 1, 2-Region 2, 3-Region 3, 4-First surface, 5-Second surface, 6-Non-working surface, φd1±a-Diameter of the outer circular outline of Region 1 near the outer edge of the substrate, φd2±b-Diameter of the outer circular outline of Region 2 near the outer edge of the substrate. The outer diameter of the circular substrate, S±g - thickness of the substrate, G - required roughness of the first and second surfaces, R - radius of curvature of the spherical region to be processed, r - radius of the bottom circle of the spherical cap, H - sag, φd2±i - diameter of the circular opening on the top of the tooling used when changing the spherical curvature radius of the inner region of the bottom circle of the φd2 spherical cap, φd1±j - diameter of the circular opening on the top of the tooling used when changing the spherical curvature radius of the inner region of the bottom circle of the φd1 spherical cap, φd4 - bottom circle diameter of the outer cylindrical surface of the circular bottle cap-shaped tooling, φd3±h - bottom circle diameter of the inner cylindrical surface of the circular bottle cap-shaped tooling, K - height of the flange around the circular bottle cap-shaped tooling, L - thickness of the top of the circular bottle cap-shaped tooling. Detailed Implementation

[0050] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0051] See Figure 1 and Figure 2 The present invention discloses a high-precision, high-curvature focusing lens, comprising a glass substrate with an integral structure; defining the front and back surfaces of the substrate as a first surface 4 and a second surface 5, respectively; the first surface 4 is planar; the second surface 5 includes multiple spherical regions, each with a different radius of curvature, and includes spherical regions with a radius of curvature greater than or equal to 20,000 mm.

[0052] To improve the optical stability and radiation resistance of the focusing lens and better meet the application requirements in the aerospace field, the high-precision, high-curvature focusing lens of this embodiment preferably uses fused silica glass as the substrate material. For ease of focusing, see [link to documentation]. Figure 1 and Figure 2 In this embodiment of the high-precision, high-curvature focusing lens, the glass substrate is preferably circular; multiple spherical regions are arranged concentrically adjacent to each other from the inside out, and the radius of curvature of the spheres increases sequentially from the inside out; in this embodiment, all of the above-mentioned multiple spherical regions are convex. See also Figure 1 In this embodiment, the second surface 5 includes two spherical regions: region 1 and region 2. The second surface 5 also includes an annular planar region located on the outermost side of the plurality of spherical regions. Figure 1Region 3 is shown in the figure. In this embodiment, the high-precision, high-curvature focusing lens preferably has a width dimension of less than 0.1 mm in the radial direction of the projection of the transition region between two adjacent spherical regions and between adjacent spherical and planar regions onto the plane containing the outer contour line of the substrate. This results in a larger effective focusing aperture for the focusing lens.

[0053] The specific dimensions of the high-precision, high-curvature focusing lens in this embodiment are as follows: Figure 1 and Figure 2 As shown, where: φd1±a equals φ15.2±0.03mm; φd2±b equals φ22±0.03mm; equal mm; S±g equals 6±0.05mm; G equals 0.008±0.001μm; the radius of curvature of the sphere in region 1 is 22506±2000mm, the radius of curvature of the sphere in region 2 is 46082±2000mm, and the spheres in both region 1 and region 2 are convex; region 3 is planar; the circumferential cylindrical surface of the focusing lens is the non-working surface 6.

[0054] See Figure 3 The present invention also provides a method for processing high-precision, high-curvature focusing lenses, comprising the following steps:

[0055] Step 1: Select a substrate with corresponding radial and thickness dimensions and made of glass, based on the radial and thickness requirements of the focusing lens to be processed;

[0056] Step 2: Fix the substrate selected in Step 1 using the optical adhesive mounting method; then polish the front and back surfaces of the substrate. During the polishing process, use a planar template in conjunction with an interferometer to detect the planar surface shape error. Detect the planar surface shape of the two polished surfaces to ensure that the RMS value of the planar surface shape of the two surfaces is better than 0.02λ, where λ refers to the wavelength of the standard light source on the interferometer.

[0057] Step 3: Based on the distribution and radius of curvature of the areas to be processed on the substrate surface, as well as the spherical area to be processed, make corresponding fixtures. The fixtures are designed to completely cover the area on the substrate surface except for the area to be processed by the next ion beam equipment, leaving only the area to be processed by the next ion beam equipment exposed. Then, install the fixtures onto the substrate after polishing in Step 2.

[0058] Step Four: The exposed area to be processed by the next ion beam equipment in Step Three is processed using an ion beam device. During processing, an interferometer is used to detect the POWER value to control the radius of curvature of the processed sphere, so as to obtain a sphere with a radius of curvature that meets the design requirements. After the radius of curvature of the processed area meets the design requirements, the ion beam equipment stops processing, and then the tooling is removed; see [link to relevant documentation]. Figure 4 Based on the radius of curvature R of the spherical region to be processed and the radius r of the bottom circle of the corresponding spherical cap, the height of the spherical cap is calculated. The height of the spherical cap is the sagitta H of the spherical region to be processed. Then, the sagitta H is converted into a POWER value to obtain the above POWER value.

[0059] Step 5: Repeat steps 3 and 4 until all spherical areas to be processed are completed, thus obtaining the required high-precision, high-curvature focusing lens.

[0060] In order to improve the optical stability and radiation resistance of the final focusing lens and better meet the application requirements of the aerospace field, the glass material in step one above can preferably be fused silica glass.

[0061] To prevent contamination of the ion beam equipment during processing and avoid significant economic losses, the tooling in step three above can preferably be graphite tooling.

[0062] For ease of focusing, to better ensure the accuracy of the final processed focusing lens, and to increase the effective focusing aperture of the final processed focusing lens, the substrate shape in step one is preferably circular; in step three, the graphite fixture is preferably a circular bottle cap with an opening on top and flanges around the edges; the internal radial dimension of the circular bottle cap matches the radial dimension of the substrate; the position and size of the opening on top correspond to the area to be processed by the next step ion beam equipment in step three; the dimensional accuracy of the graphite fixture should preferably meet the following condition: the width of the projection of the transition area of ​​each adjacent area on the plane of the outer contour line of the substrate on the surface of the processed spherical area along the radial direction of the substrate is less than 0.1 mm.

[0063] To achieve higher precision in the final focusing lens, in step four above, when using an interferometer to detect the POWER value and controlling the radius of curvature of the processed sphere, the standard lens used in the interferometer is preferably a plane lens, and the POWER value detection precision of the interferometer is preferably 0.001λ to 0.01λ.

[0064] In the process of processing a high-precision, large-curvature focusing lens using the processing method of this invention, when steps three and four are executed cyclically to complete the processing of all spherical areas to be processed, different processing sequences can be selected for multiple spherical areas to be processed based on the distribution and radius of curvature of each area to be processed on the substrate surface to be processed, and different tooling can be used. The following provides two distributions and radii of curvature of each area to be processed on the substrate surface to be processed, along with the specific processing sequence and the specific areas to be processed by the ion beam equipment in the next step mentioned in step three. That is, it provides the areas that the tooling should block when preparing the tooling in step three, to facilitate the specific application of the high-precision, large-curvature focusing lens processing method of this invention; specifically:

[0065] In step three, the substrate surface to be processed includes multiple concentrically arranged spherical regions with increasing radii of curvature from the inside out. The processing is repeated in steps three and four to complete the processing of all spherical regions. Each spherical region is processed sequentially from the outside in. Furthermore, when processing each spherical region, the next area to be processed by the ion beam equipment in step three is the area within the outer contour line of the spherical region to be processed, closest to the outer edge of the substrate.

[0066] Alternatively: In step three, the substrate surface to be processed includes multiple concentrically arranged spherical regions to be processed, arranged from the inside out, with the radius of curvature decreasing from large to small. When processing in a cyclical manner according to steps three and four to complete the processing of all spherical regions to be processed, each spherical region to be processed is processed sequentially from the inside out. When processing each spherical region to be processed, the area to be processed by the next ion beam device in step three is the area between the outer contour line of the outermost spherical region to be processed near the outer edge of the substrate and the inner contour line of the spherical region to be processed near the center of the substrate.

[0067] To improve the radiation resistance of the high-precision high-curvature focusing lens processed by the processing method of the present invention, step five of the processing method of the high-precision high-curvature focusing lens in this embodiment is specifically as follows: Steps three and four are executed cyclically until all spherical areas to be processed are completed. Then, an antireflective coating is deposited on the substrate after all spherical areas to be processed are processed using a coating machine. The outermost layer of the antireflective coating is made of SiO2, thus obtaining the desired high-precision high-curvature focusing lens.

[0068] The following describes the processing method for high-precision, high-curvature focusing lenses using the present invention. Figure 1 and Figure 2 The structure shown is also the processing procedure for the high-precision, high-curvature focusing lens of this invention. Figure 5This is a process flow chart, which specifically includes the following steps:

[0069] Step 1: Select a substrate;

[0070] Select a radial dimension equal to A substrate with a thickness of 6 ± 0.05 mm;

[0071] Step 2: Fix the substrate selected in Step 1 using a photoresist mounting method; then polish the front and back surfaces of the substrate. During the polishing process, use a planar template in conjunction with an interferometer to detect the planar surface shape error, and detect the planar surface shape of the two polished surfaces to ensure that the RMS value of the planar surface shape of the two surfaces is better than 0.02λ, where λ refers to the wavelength of the standard light source on the interferometer. In this embodiment, λ is 632.8nm.

[0072] After the second polishing step is completed, steps three and four need to be repeated to complete the processing of all spherical areas. In this embodiment, the processing of spherical area 2 (area two) is completed first; then the processing of spherical area 1 (area one) is completed. Therefore, steps three and four are as follows:

[0073] Step 3: Modify the radius of curvature of the spherical surface within the bottom circle of the Φd2 spherical cap to make the radius of curvature of the spherical surface within this region 46082±2000mm, specifically:

[0074] First make such Figure 6 (A) shows a graphite fixture, in which: φd2±i equals φ22±0.01mm, φd3±h equals φ59±0.02mm, φd4 equals φ65mm, K equals 6mm, and L equals 2mm;

[0075] Then the tooling is installed onto the substrate that has been polished in the second step;

[0076] Next, an ion beam device is used to process the exposed areas of the surface to be processed that are not covered by the graphite tooling. During the processing, an interferometer is used to detect the POWER value to control the radius of curvature of the processed sphere in order to obtain a sphere with a radius of curvature that meets the design requirements. Figure 4 This is a schematic diagram illustrating the calculation of the sag of the spherical region to be processed. Figure 4 In this equation, R is the radius of curvature of the spherical region to be processed, r is the radius of the base circle of the spherical cap, and H is the sag. Therefore, the sag H can be calculated by the following formula [1]: Formula [1] is:

[0077]

[0078] The sag of region 2 was calculated to be 0.00126mm~0.00137mm using formula [1], and its POWER value was converted to -2.165λ~-1.991λ.

[0079] When the radius of curvature in region 2 reaches 46082±2000 mm, the ion beam equipment stops processing and then the tooling is removed.

[0080] Step 4: Modify the radius of curvature of the spherical surface within the bottom circle of the Φd1 spherical cap to make the radius of curvature of the spherical surface within this region 22506±2000mm, specifically as follows:

[0081] First make such Figure 6 (B) shows the graphite fixture, where: φd1±j equals φ15.2±0.01mm, φd3±h equals φ59±0.02mm, φd4 equals φ65mm, K equals 6mm, and L equals 2mm;

[0082] Then the tooling is installed onto the substrate that has been processed in the third step;

[0083] Next, an ion beam device was used to process the exposed area of ​​the graphite tooling on the surface to be processed. During the processing, the POWER value was detected by an interferometer to control the radius of curvature of the processed sphere so as to obtain a sphere with a radius of curvature that meets the design requirements. The sag of region 1 was calculated to be 0.00118mm to 0.00141mm by the above formula [1] and converted to a POWER value of -2.228λ to -1.865λ.

[0084] When the radius of curvature in region 1 reaches 22506±2000 mm, the ion beam equipment stops processing and then the tooling is removed.

[0085] Step 5: Using a coating machine, an antireflective coating is applied to the substrate with the two spherical regions processed in Step 4. The outermost layer of the antireflective coating is made of SiO2. This results in a focusing lens with better radiation resistance after the antireflective coating is applied.

[0086] In the processing of this embodiment, by controlling the dimensional tolerance of the graphite tooling, it can be ensured that the width of the transition area between region 1 and region 2, and between region 2 and region 3, projected onto the plane containing the outer contour line of the substrate along the radial direction of the substrate is less than 0.1mm, thus making the effective focusing aperture of the focusing lens larger.

[0087] Figure 7 It is obtained by processing the high-precision, high-curvature focusing lens using the processing method of this invention. Figure 1 and Figure 2 The structure shown is also the surface profile of the high-precision, high-curvature focusing lens of this embodiment of the invention, wherein: (C) is the surface profile of the region Φd1; (D) is the surface profile of the region Φd1~Φd2; (E) is the surface profile of the region Φd2~Φd3; from Figure 7As shown in (C), the POWER value in region 1 is -1.978λ; Figure 7 As shown in (D), the POWER value in region 2 is -2.164λ; Figure 7 As can be seen in (E), the RMS in region 3 is 0.015λ; therefore, it can be ensured that the radius curvature of each region meets the technical requirements.

[0088] Figure 8 This is a physical image of an embodiment of the high-precision, high-curvature focusing lens of the present invention.

[0089] In summary, the high-precision large curvature focusing lens processing method of the present invention can meet the processing requirements of large curvature radius spherical surfaces with curvature radius of 20m to 100m, and the processing focusing lens error is within 1%.

Claims

1. A method for processing a high-precision, high-curvature focusing lens, wherein the high-precision, high-curvature focusing lens comprises a circular substrate of glass material with an integral structure; the front and back surfaces of the substrate are defined as a first surface (4) and a second surface (5), respectively; the first surface (4) is planar; the second surface (5) includes multiple spherical regions, each with a different radius of curvature, and includes spherical regions with a radius of curvature greater than or equal to 20,000 mm; characterized in that, Includes the following steps: Step 1: Select a circular substrate with corresponding radial and thickness dimensions and made of glass, based on the radial and thickness requirements of the focusing lens to be processed; Step 2: Fix the substrate selected in Step 1 using optical adhesive mounting; then polish the front and back surfaces of the substrate. During the polishing process, use a planar template in conjunction with an interferometer to detect the planar surface shape error, and detect the planar surface shape of the two polished surfaces to ensure that the RMS value of the planar surface shape of the two surfaces is better than 0.02λ, where λ refers to the wavelength of the standard light source on the interferometer. Step 3: Based on the distribution and radius of curvature of the areas to be processed on the substrate surface, as well as the spherical area to be processed, a corresponding fixture is fabricated. This fixture is designed to completely cover the area on the substrate surface except for the area to be processed by the next ion beam equipment, exposing only the area to be processed. The fixture is a graphite fixture, shaped like a circular bottle cap with an opening at the top and flanged edges around the edges. The internal radial dimension of the circular bottle cap matches the radial dimension of the substrate. The position and size of the opening at the top correspond to the area to be processed by the next ion beam equipment. The dimensional accuracy of the graphite fixture should meet the following condition: the width of the projection of the transition area between adjacent areas on the plane of the substrate's outer contour line along the radial direction of the substrate surface after the spherical area has been processed is less than 0.1 mm. Then, the fixture is installed onto the substrate after polishing in Step 2. Step 4: The exposed area to be processed by the next ion beam equipment in Step 3 is processed using an ion beam device. During the processing, an interferometer is used to detect the POWER value to control the radius of curvature of the processed sphere, so as to obtain a sphere with a radius of curvature that meets the design requirements. After the radius of curvature of the processed area meets the design requirements, the ion beam equipment stops processing and the tooling is removed. The height of the spherical cap is calculated based on the radius of curvature (R) of the spherical area to be processed and the base circle radius (r) of the corresponding spherical cap. The height of the spherical cap is the sagitta (H) of the spherical area to be processed. Then, the sagitta (H) is converted into a POWER value to obtain the POWER value. Step 5: Repeat steps 3 and 4 until all spherical areas to be processed are completed, thus obtaining the required high-precision, high-curvature focusing lens.

2. The processing method for a high-precision, high-curvature focusing lens according to claim 1, characterized in that: In step four, when using an interferometer to detect the POWER value and controlling the radius of curvature of the processed sphere, the standard lens used in the interferometer is a plane lens, and the POWER value detection accuracy of the interferometer is 0.001λ~0.01λ.

3. The processing method for a high-precision, high-curvature focusing lens according to claim 1, characterized in that: In step one, the glass material is fused silica glass. Step five specifically involves repeating steps three and four until all spherical areas to be processed are completed. Then, using a coating machine, an antireflective coating is deposited on the substrate after all spherical areas have been processed. The outermost layer of the antireflective coating is made of SiO2, thus obtaining the desired high-precision, high-curvature focusing lens.

4. The processing method for a high-precision, large-curvature focusing lens according to any one of claims 1 to 3, characterized in that: The substrate surface to be processed in step three includes multiple concentrically arranged spherical regions to be processed, arranged from the inside out, with the radius of curvature increasing from small to large. When processing in steps three and four in a cyclical manner to complete the processing of all spherical regions to be processed, each spherical region to be processed is processed in the order of processing from the outside in. When processing each spherical region to be processed, the area to be processed by the next ion beam equipment in step three is the area within the outer contour line of the spherical region to be processed, which is close to the outer edge of the substrate. Alternatively: Step 3 describes a substrate surface to be processed that includes multiple concentrically arranged, adjacent regions with decreasing radii of curvature from the inside out. When processing all the spherical regions in Step 3 and Step 4 in a cyclical manner, each spherical region is processed sequentially from the inside out. Furthermore, when processing each spherical region, the area to be processed by the next ion beam device in Step 3 is the region between the outermost spherical region's outer contour line near the substrate's outer edge and the inner contour line of the spherical region to be processed near the substrate's center.

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