A processing method of an ultra-thin plano-convex lens

Abstract

The application provides a processing method of an ultrathin plano-convex lens, comprising the following steps: fixing a blank on a parallel disc, performing rough grinding on a first surface to obtain a first rough grinding blank; polishing the first rough grinding blank to obtain a first rough grinding and polishing blank; fixing the first surface of the first rough grinding and polishing blank on the parallel disc, performing rough grinding on a second surface of the first rough grinding and polishing blank to obtain a second rough grinding blank; polishing the second rough grinding blank to obtain a second rough grinding and polishing blank; fixing the second surface of the second rough grinding and polishing blank on a light cementing disc, performing fine grinding on the first surface of the second rough grinding and polishing blank to obtain a first fine grinding lens; fixing the first surface of the first fine grinding lens on the light cementing disc through a backing plate, performing fine grinding on the overall shape of the first fine grinding lens to form a spherical surface, and obtaining a plano-convex lens. The problem that the existing ultrathin plano-convex lens parts are prone to deformation due to thin size and thus cannot meet the standards is solved.

Description

Technical Field

[0001] This application relates to the field of optical component processing technology, and more specifically, to a processing method for an ultrathin plano-convex lens. Background Technology

[0002] Among various optical lenses, plano-convex lenses are required. A plano-convex lens has one flat surface (first surface) and the other flat surface (second surface) (spherical surface). Plano-convex lenses have a positive focal length and are typically used to reduce the size of a light beam, decrease the focal length, or magnify an image. To reduce spherical aberration, when a plano-convex lens is used to collimate and focus a light beam, the beam is incident on the convex surface of the lens; when used to collimate a point light source, the beam is incident on the flat surface. Plano-convex lenses focus light rays into a single point and are commonly used for aiming and focusing monochromatic light sources. Ultra-thin plano-convex lenses are a special type of plano-convex lens, defined as having a center thickness to diameter ratio < 1:10 and an edge thickness < 0.5 mm (thinner at the edges).

[0003] In the processing of ultra-thin plano-convex lenses, the parts typically need to be bonded and fixed onto a parallel plate for grinding and polishing. Rosin wax is usually used as the adhesive, which exerts tension on the parts during bonding. After polishing and removing the parts from the plate, the internal stress causes the surface to tend to become concave. Therefore, the front surface of the plate needs to be convex to compensate for the surface deformation caused by the tension of the rosin wax. However, existing processing equipment often only guarantees planar processing when a flat surface is required, and it is difficult to guarantee the processing of convex surfaces. As a result, ultra-thin plano-convex lens parts cannot meet the high-precision quality requirements during processing.

[0004] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0005] The purpose of this application is to provide a processing method for ultra-thin plano-convex lenses, which solves the problem that existing ultra-thin plano-convex lens parts are prone to deformation due to their thin size during processing, resulting in products that cannot meet high-precision quality requirements.

[0006] To achieve the above objectives, the technical solution adopted in this application is as follows:

[0007] This application provides a method for manufacturing an ultrathin plano-convex lens, including the following steps:

[0008] Multiple blanks are fixed on a parallel disc, and the first surface of the blanks is rough ground to obtain the first rough-ground blank.

[0009] The first rough grinding blank is polished to release internal stress, resulting in the first rough grinding polished blank.

[0010] The first surface of the first rough polishing blank is fixed on the parallel disk, and the second surface of the first rough polishing blank is rough ground to obtain the second rough polishing blank.

[0011] The second rough grinding blank is polished to obtain the second rough grinding polished blank;

[0012] The second surface of the second rough polishing blank is fixed onto the optical adhesive disk, and the first surface of the second rough polishing blank is finely processed to obtain the first finely processed lens.

[0013] The first surface of the first finely processed lens is fixed on the optical film disk by a pad, and the overall shape of the second surface of the first finely processed lens is finely processed to form a spherical surface, thereby obtaining a plano-convex lens.

[0014] In an optional embodiment, in the step of fixing the blank on a parallel disk and rough grinding the first surface of the blank to obtain a first rough-ground blank:

[0015] The first surface of the blank is gradually polished until the polished blank reaches the first preset size, and the height difference of multiple polished blanks on the parallel disc is no greater than 0.005mm, wherein the grit of the polishing tool corresponding to the gradual polishing gradually increases.

[0016] In an optional embodiment, in the step of fixing the first surface of the first rough-polished blank to the parallel disk and performing rough grinding on the second surface of the first rough-polished blank to obtain the second rough-polished blank:

[0017] The first surface of the first rough polishing blank is fixed, and the second surface of the first rough polishing blank is gradually polished to obtain the second rough polishing blank. The second rough polishing blank reaches the second preset size, and the height difference of multiple second rough polishing blanks on the parallel disc is no greater than 0.005mm. The grit number of the polishing tool corresponding to the gradual polishing gradually increases.

[0018] In an optional embodiment, in the step of polishing the second rough-grind blank to obtain the second rough-grind polished blank:

[0019] The second rough grinding blank is polished in stages to obtain the first rough grinding polished blank, so that the second surface of the first rough grinding polished blank meets the preset planar surface shape requirements, wherein the polishing speed of the staged polishing process is gradually reduced.

[0020] In an optional embodiment, in the step of fixing the second surface of the second rough-polished blank to the optical adhesive disk and then finishing the first surface of the second rough-polished blank to obtain the first finished lens:

[0021] Fix it by second rough grinding and polishing the second surface of the blank, and gradually grind the first surface of the second rough grinding and polishing blank to make the second rough grinding and polishing blank after grinding reach the third preset size, and the height difference of multiple second rough grinding and polishing blanks after grinding on the optical cementing plate is not greater than 0.005 mm. The mesh number of the grinding tool corresponding to the gradual grinding gradually increases. The third preset size = standard size + convex surface machining allowance;

[0022] Perform step-by-step polishing on the second rough grinding and polishing blank after grinding to obtain the first precision-machined lens, so that the first surface of the first precision-machined lens meets the preset flat surface shape requirement, and the polishing speed in the step-by-step polishing process gradually decreases.

[0023] In an optional embodiment, in the step of fixing the first surface of the first precision-machined lens on the optical cementing plate through the backing plate and performing precision machining on the overall shape of the second surface of the first precision-machined lens to form a spherical surface and obtain a plano-convex lens:

[0024] Optically cement and fix the first surface of the first precision-machined lens on the backing plate, and adsorb the first precision-machined lens and the backing plate through tooling positioning during the optical cementing process;

[0025] Milling and grinding the overall shape of the first precision-machined lens to form a spherical surface with a predetermined size on the second surface of the first precision-machined lens. The height difference of the spherical surfaces of multiple first precision-machined lenses on the optical cementing plate is less than 0.03 mm, the spherical surface meets the preset surface shape requirement, and the first precision-machined lens after milling and grinding reaches the fourth preset size. The fourth preset size = standard size + fine grinding allowance;

[0026] Grind the spherical surface of the first precision-machined lens so that the first precision-machined lens after grinding reaches the upper limit value of the standard size and the surface shape of the spherical surface reaches 0 to -2 μm;

[0027] Polish the spherical surface of the first precision-machined lens after grinding so that the spherical surface aperture grade is N = ±3, the surface shape requirement <lambda / 10@633nm, and the roughness < 0.5 nm to obtain a plano-convex lens.

[0028] In an optional embodiment, the backing plate matches the outer contour of the plano-convex lens;

[0029] The surface shape deviation between the two opposite surfaces of the backing plate and the optical cementing plate is: N ≤ 0.2, ΔN ≤ 0.2, where N represents the aperture number and ΔN represents the local aperture number;

[0030] The parallelism of the two opposite surfaces of the backing plate is less than 30〃.

[0031] In an optional embodiment, the tooling includes: a bottom plate and a positioning plate, and the positioning plate is vertically arranged on the bottom plate;

[0032] The pad is placed on the base plate and abuts against the positioning plate, and the first precision-machined lens abuts against the positioning plate and is lowered onto the pad.

[0033] In an optional embodiment, before fixing the first surface of the first finished lens to the pad with photoresist, wherein the photoresist process involves positioning the first finished lens to adhere to the pad using a tooling, the method further includes:

[0034] The actual thickness of the pad is randomly checked and recorded. The actual thickness of the pad is used to calculate the grinding amount when grinding the spherical surface of the first precision-machined lens.

[0035] In an optional embodiment, in the step of fixing multiple blanks on a light-reflecting disc and rough grinding the first surface of the blanks to obtain a first rough-ground blank:

[0036] Heat the parallel plate and apply rosin wax, wherein the weight ratio of rosin to white wax in the rosin wax is 1:1;

[0037] The second surface of the blank is bonded to the parallel disc, and the edges of the blank are protected with adhesive.

[0038] The beneficial effects of the processing method for an ultrathin plano-convex lens provided in this application are at least as follows: First, the first surface of the blank is rough-ground to obtain a first rough-ground blank. The first rough-ground blank is then polished to release internal stress, resulting in a first rough-ground polished blank. This effectively reduces the internal stress generated in the first roughing process. Next, the second surface of the first rough-ground polished blank is rough-ground to obtain a second rough-ground blank. The second rough-ground blank is then polished to release the internal stress generated in the second roughing process. Because the internal stress is released, the deformation caused by the internal stress during the roughing process is greatly reduced in subsequent finishing. Then, a light adhesive pad is used for light adhesive fixation, and the first surface of the second rough-ground polished blank is finished to obtain a first finished lens. In this way, the use of light adhesive fixation instead of rosin wax or other adhesives for fixation during the finishing process avoids the problem of adhesives causing tensile stress on the part and thus deforming the finished part. Finally, the second surface of the first precision-machined lens is fixed to the optical adhesive tray using a pad, resulting in a plano-convex lens. This method not only avoids deformation caused by tension by using optical adhesive instead of rosin wax or other adhesives for fixation, but also increases the thickness of the workpiece by fixing the pad and the first precision-machined lens as a whole. Therefore, the pad enhances the structural strength of the first precision-machined lens during processing, especially increasing the thickness of the thinner edge, providing stable support for the thinner edge during processing. This makes the thinner edge of the first precision-machined lens less prone to deformation and damage during the finishing process, thus ensuring that the optical lens meets high-precision quality requirements during processing. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 A flowchart illustrating the main steps of a method for fabricating an ultrathin plano-convex lens according to an embodiment of this application;

[0041] Figure 2 A flowchart illustrating the detailed steps of a method for manufacturing an ultrathin plano-convex lens, as provided in this application embodiment.

[0042] Figure 3 A schematic diagram showing the dimensions of a plano-convex lens from a blank to a finished product, provided for an embodiment of this application, in a method for processing an ultrathin plano-convex lens.

[0043] Figure 4 A schematic diagram of the structure of the pad used in a processing method for an ultrathin plano-convex lens provided in this application embodiment;

[0044] Figure 5 A schematic diagram of the optical adhesive disk used in a method for processing an ultrathin plano-convex lens according to an embodiment of this application;

[0045] Figure 6 A schematic diagram illustrating the principle of the tooling used in a method for processing an ultrathin plano-convex lens according to an embodiment of this application;

[0046] Figure 7 This is a diagram showing the arrangement of the first precision-processed lens on the optical disc in a method for processing an ultrathin plano-convex lens according to an embodiment of this application.

[0047] The following are the labeling elements in the figure:

[0048] 10. Blank; 20. Plano-convex lens; 21. First-finished lens; 30. Optical disc; 40. Pad; 50. Tooling; 51. Base plate; 52. Positioning plate. Detailed Implementation

[0049] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0050] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it may be directly or indirectly located on that other component. When a component is referred to as "connected to" another component, it may be directly or indirectly connected to that other component. The terms "upper," "lower," "left," "right," "front," "rear," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate orientations or positions based on the accompanying drawings, and are for ease of description only, and should not be construed as limiting the technical solution. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features. "A plurality" means two or more, unless otherwise explicitly defined.

[0051] The technical terms related to the solution in this embodiment are explained as follows:

[0052] Surface shape: PV (Peak to Valley), also known as peak-to-valley value, is a common indicator of the surface shape quality of optical surfaces. It refers to the height difference between the highest and lowest points within a sampling range (based on 2D contour lines or 3D data maps), after removing the reference plane. PV values ​​are expressed in units of physical length. Based on the required reference plane, the maximum deviation range of all pixels directly reflects the current processing quality of the optical surface. Based on long-term experience in optical testing, PV values ​​and another important surface shape indicator, RMS, often maintain a certain proportional relationship, generally around 2:1.

[0053] Backing plate: A tooling used to support the machining of convex surfaces, with very high parallel accuracy, reaching the second level.

[0054] Rosin wax: Used to bond and fix optical components during surface processing.

[0055] Photopolymer bonding: A method for bonding complex optical components. Because there is no medium between the bonding surfaces, the optical properties remain unchanged. Compared with adhesive layer bonding, photopolymer bonding offers higher mechanical strength, more stable performance that can last for decades, less deformation, and better cold and heat resistance. However, the photopolymer bonding process requires very high manufacturing precision for the bonded surface.

[0056] The requirements for the gluing surface in the gluing process are as follows: Gluing is a process that relies on intermolecular attraction to tightly bond two surfaces together. The intermolecular attraction between surfaces is a statistical physical phenomenon; it does not act on the entire gluing surface, but rather between the microscopic peaks or troughs of the two surfaces. Because the peaks and troughs are small and densely packed, the statistical area generating molecular attraction is quite large, sufficient to bond the two surfaces together. Furthermore, gluing begins by applying pressure to the edges of the part, causing the gluing to proceed to that area first. Near the interface between the glued and unglued surfaces, deformation occurs due to molecular attraction, causing the unglued surfaces to reach the range of intermolecular attraction. Therefore, the gluing bonding surface gradually expands until the entire bonding surface is glued together.

[0057] Intermolecular forces can be expressed by the following formula:

[0058] In the formula: F represents the intermolecular force; λ and μ are coefficients, both positive numbers; r is the intermolecular distance; s and t are constants that vary with the substance, typically s = 9–12 and t = 4–7. The first term on the right-hand side represents the repulsive force, and the second term represents the attractive force. Because s > t, the attractive force is greater than the repulsive force. Since s and t are relatively large, F increases as r decreases.

[0059] Generally, attraction occurs when r = 10⁻³ μm to 10⁻⁴ μm, meaning that intermolecular attraction can only be observed when the distance between the two photoresist surfaces is in the range of 0.001 μm to 0.01 μm. This is based on the surface error requirements for the photoresist.

[0060]

[0061] Obviously, producing such a high-precision polished surface is very difficult, and even if it were achieved, it would be very difficult to inspect. The amount of deformation caused by minute changes in the surrounding medium would be 10 orders of magnitude larger than this error. Subsequently, the thickness of the gloss-coated parts, the matching of the gloss-coated parts' apertures, and the consistency of their outer diameters are selected according to technical requirements. The aperture size is N≤0.2, ΔN≤0.2, and the surface imperfection level is not lower than 3×0.16 as specified in the national standard GB1182-89. The gloss-coated parts should be placed at a constant temperature of 20℃±1℃ for several hours to ensure uniform temperature throughout.

[0062] CNC polishing: Computer numerical control uses computer code to convert 3D CAD models into machined parts. CNC has a high degree of data quantification, a high degree of parameterization in the product processing, is less affected by human factors, and has relatively stable product quality. It can achieve fixed time, fixed aperture, fixed size, and fixed surface shape.

[0063] High-efficiency polishing: The quasi-spherical high-speed polishing method is adopted to increase the spindle speed of the machine tool and increase the polishing pressure, so as to produce lenses that meet the quality requirements with the highest possible processing efficiency.

[0064] Classical polishing: Classical polishing is a traditional cold working method for glass. The polishing machine uses friction wheel drive, the spindle speed is relatively low, and pressure is applied by a planar swing tripod, with the pressure adjusted by the load weight.

[0065] Please see Figure 1 , Figure 3 This embodiment proposes a processing method for ultra-thin plano-convex lenses, used for processing ultra-thin plano-convex lens parts, and ensuring that the processed plano-convex lens 20 meets high-precision quality requirements. For ease of structural description, the plano-convex lens 20 (ultra-thin plano-convex lens type) has one side forming a plane as the first surface and the other side forming a convex surface (spherical surface) as the second surface (intermediate transition semi-cost parts formed during the forming process of ultra-thin plano-convex lens parts are also described with reference to this standard). The quality of the ultra-thin plano-convex lens obtained by this method can achieve the following: the surface shape requirement of the first surface (plane) is PV < Lambda / 10@633nm; the effective light transmission diameter of the first surface is Φ20mm. The surface shape requirement of the second surface (spherical surface) is PV < Lambda / 10@633nm; the effective light transmission diameter of the second surface is Φ20mm; the surface roughness of the second surface is RMS <0.5nm; and the center thickness of the entire ultra-thin plano-convex lens is ±0.1mm. The remaining surfaces of the ultra-thin plano-convex lens are frosted surfaces (e.g., the outer cylindrical side surface).

[0066] Please see Figure 3 In this embodiment, the specifications of the processed plano-convex lens 20 (ultra-thin plano-convex lens type) are as follows: outer circle size Φ21×2mm, spherical size SR 40mm, and edge thickness 0.5mm, which will be used as an example for specific explanation.

[0067] Please see Figure 3 The specifications of the blank 10 used in this embodiment are: size Φ22×2.6mm, chamfer size C0.3; machining allowance of 0.25mm for each surface.

[0068] like Figure 1 , Figure 2 As shown, the processing method of an ultrathin plano-convex lens in this embodiment includes the following steps:

[0069] Step S100: Fix multiple blanks on a parallel disc and perform rough grinding on the first surface of the blanks to obtain the first rough-ground blank.

[0070] In the specific process, after the blank is fixed by bonding with parallel discs, the first surface of the blank is rough machined.

[0071] Step S100 in this embodiment specifically includes:

[0072] Step S110: Heat the parallel plate and apply rosin wax, wherein the weight ratio of rosin to white wax in the rosin wax is 1:1.

[0073] Step S120: Attach the second surface of the blank to the parallel disc and apply adhesive to protect the edges of the blank.

[0074] In the above process, one side of the blank is first wiped clean and used as the second surface. Then, the parallel plate is heated and rosin wax is applied. The rosin wax formed by the ratio of rosin to white wax is 1:1 to ensure the bonding stability. The cleaned second surface is then bonded to the parallel plate, and finally, glue is applied for protection.

[0075] Step S130: The first surface of the blank is gradually polished so that the polished blank reaches the first preset size, and the height difference of multiple polished blanks on the parallel disc is no greater than 0.005mm, wherein the grit number of the polishing tool corresponding to the gradual polishing gradually increases.

[0076] In the specific process, the first preset dimension is 2.55 + 0.01 mm. Therefore, approximately 0.04-0.05 mm needs to be removed. This can be done in two stages of polishing, with the same thickness removed in each stage. The two stages use different grits of polishing tools: 303# for the first stage and 303.5# for the second. Therefore, the more stages of polishing, the finer the polishing tools used. Using coarser tools improves polishing efficiency, while using finer tools increases gloss and precision. This improves efficiency while ensuring product quality, allowing the height difference between the multiple polished blanks on the parallel disc to be controlled within Δt ≤ 0.005 mm.

[0077] Step S200: Polish the first rough grinding blank to release internal stress and obtain the first rough grinding polished blank.

[0078] In the specific process, the first surface after grinding is polished in a disc-like manner to increase the spindle speed of the machine tool and make the first surface bright. Due to its ultra-thin thickness, the ultra-thin plano-convex lens will have residual stress introduced during processing. By polishing one side of the first rough grinding blank, the residual stress caused by the change in product structure is eliminated, and the deformation of the part due to stress is avoided in subsequent processing.

[0079] After rough machining of the first surface of the blank, a first rough polished blank is obtained. The first rough polished blank is then removed from the parallel disc by heating it and cleaned.

[0080] Step S300: Fix the first surface of the first rough polishing blank onto the parallel disk, and perform rough grinding on the second surface of the first rough polishing blank to obtain the second rough polishing blank.

[0081] This step involves rough machining of the second surface of the blank using a parallel disc. Therefore, step S300 specifically includes:

[0082] Step S310: Use the polished first surface of the first rough grinding and polishing blank as the bonding surface, apply glue dots to the bonding surface, and bond it to the parallel disc.

[0083] In the specific process, the adhesive dots are rosin adhesive dots, and the diameter of the parallel disc is Φ183mm, so each disc can hold 54 first rough grinding and polishing blanks. After the blanks are placed on the disc, the edges of the first rough grinding and polishing blanks are coated with adhesive for protection (refer to...). Figure 7 Distribution in (the context).

[0084] Step S320: Fix the first surface of the first rough polishing blank, and gradually polish the second surface of the first rough polishing blank to obtain the second rough polishing blank. The second rough polishing blank reaches the second preset size, and the height difference of multiple second rough polishing blanks on the parallel disc is not greater than 0.005mm. The grit number of the polishing tool corresponding to the gradual polishing gradually increases.

[0085] In the specific process, the second preset dimension can be 2.38 + 0.02 mm, which is the center thickness dimension. The gradual polishing process can be divided into 3 steps: the first step uses a coarser polishing tool (280# abrasive) to remove 0.1 mm; the second step uses a slightly finer polishing tool (303# abrasive) to remove 0.05 mm; and the third step uses the finest polishing tool (303.5# abrasive) to remove 0.02 mm. Therefore, using coarser grinding tools results in a larger grinding thickness, while using finer grinding tools results in a smaller grinding thickness. The grinding thickness gradually decreases with each pass. This allows for faster grinding when the part is thicker, improving processing efficiency. As the part thickness decreases, the amount of grinding also decreases, preventing excessive pressure during grinding that could deform the part. This makes the part dimensions more controllable and improves product quality. Finally, fine grinding ensures that the center thickness of the second rough grinding blank is within 2.38 ± 0.02 mm, and the height difference between the various second rough grinding blanks can be controlled within Δt ≤ 0.005 mm. This ensures that the quality of all the second rough grinding blanks on the parallel disc is within the required range, improving the yield rate.

[0086] Step S400: Polish the second rough grinding blank to obtain the second rough grinding polished blank.

[0087] In the specific process, the second rough grinding blank is polished step by step to obtain the first rough grinding and polishing blank, so that the second surface of the first rough grinding and polishing blank meets the preset flat surface shape requirement, and the polishing speed in the step-by-step polishing process gradually decreases. By polishing the second surface of the second rough grinding blank, not only a high-precision processing reference is provided for the subsequent finishing process, but also the residual stress caused by the change of the product structure can be eliminated, so that the finally obtained lens part is not easily deformed.

[0088] The specific polishing process is as follows: First, perform disk high polishing to achieve detection polishing, so that the disk quality reaches N≤3fr; the speed of disk high polishing is fast, and lenses meeting the quality requirements are polished at the highest processing efficiency as much as possible. Then, perform disk low polishing. The speed of disk low polishing is slower than that of disk high polishing. Disk low polishing is used for polishing, and the polishing pressure adopted is small. Therefore, the influence on the deformation of the second rough grinding blank is small, and the polishing quality can be well guaranteed. The first rough grinding and polishing blank obtained can reach: B = 10 - 5, and the PV of the flat surface shape of the polished second surface < Lambda / 10 @ 633nm; before obtaining the live point, fine grinding with clear water is carried out to make the surface roughness RMS < 0.5nm, so as to provide a high-quality processing reference surface for the subsequent processing. Thus, the optical glue condition is met, which is convenient for the subsequent optical glue fixing process.

[0089] After polishing is completed, the second rough grinding blank is unloaded from the disk. The specific process can be to apply glue, freeze, and then tap to unload the disk. The unloaded second rough grinding blank is cleaned. The cleaning liquid is a mixture of acetone + alcohol. This cleaning liquid can effectively remove glue and lubricating liquid, ensure the surface of the second rough grinding blank is clean, and prepare for the next process.

[0090] Step S500: Fix the second surface of the second rough grinding and polishing blank to the optical glue disk, and perform finishing on the first surface of the second rough grinding and polishing blank to obtain the first finished lens.

[0091] This step is the finishing step of the first surface. The first surface of the first finished lens obtained after processing is used as the final plane (the first surface) of the final plano-convex lens product.

[0092] Step S500 of this embodiment specifically includes the following steps:

[0093] Step S510: Fix through the second surface of the second rough grinding and polishing blank, and gradually grind the first surface of the second rough grinding and polishing blank so that the polished second rough grinding and polishing blank reaches the third preset size, and the height difference between multiple polished second rough grinding and polishing blanks on the optical glue disk is not greater than 0.005mm. The mesh number of the grinding tool corresponding to the gradual grinding gradually increases, and the third preset size = standard size + convex surface processing allowance.

[0094] Since both sides of the second rough grinding and polishing blank are polished surfaces, the second surface of the second rough grinding and polishing blank is used as the bonding surface for optical gluing. It is optically glued and fixed to the optical gluing plate, still using 54 pieces / Φ183 plate. In this way, the 54 second rough grinding and polishing blanks on the whole plate are processed synchronously, thus improving the efficiency of mass production. After loading the plate, glue is applied to protect the edges of the second rough grinding and polishing blanks.

[0095] During the process of gradually grinding the first surface of the second rough grinding and polishing blank, it can be divided into two steps. In the first step, a coarser grinding tool (303# sand) is used to grind off 0.08 mm. In the second step, a slightly finer grinding tool (303.5# sand) is used to grind off 0.03 mm. By using the step-by-step grinding method, the deformation amount generated due to processing pressure during the grinding process can be effectively controlled, thus ensuring the dimensional controllability during the processing. The processing quality of the product is improved. Finally, through fine grinding, the central thickness of the second rough grinding and polishing blank after grinding can be ensured to be 2.27 + 0.02 mm (compared with the finished product size of 2 + 0.1), leaving a margin for processing the convex surface on the other side (the convex surface processing margin, for example, the convex surface processing margin can be 0.17 mm - 0.27 mm). The height difference between the processed second rough grinding and polishing blanks can be controlled to Δt ≤ 0.005 mm. In this way, the quality of all parts on the entire parallel plate can be controlled within the required range, improving the yield rate.

[0096] Step S520: Gradually polish the second rough grinding and polishing blank after grinding to obtain the first precision-machined lens, so that the first surface of the first precision-machined lens meets the preset flat surface shape requirement, where the polishing speed in the step-by-step polishing process gradually decreases.

[0097] In the specific process, the first surface of the second rough grinding and polishing blank after grinding is gradually polished. In the step-by-step polishing process, first, high-speed disk polishing is used. The polishing speed of high-speed disk polishing is fast, and rapid rotation is achieved for detection polishing, so that the disk quality reaches N ≤ 3 fr. Then, low-speed disk polishing is carried out. The speed of low-speed disk polishing is slower than that of high-speed disk polishing. Low-speed disk polishing is used for polishing, and the polishing pressure used is small. Therefore, the influence on the deformation of the second rough grinding blank after grinding is small, and the polishing quality can be well guaranteed. The first precision-machined lens obtained can reach: B = 10 - 5, and the PV of the flat surface shape of the polished first surface < Lambda / 10 @ 633 nm (the process requirement surface shape is controlled according to 0.2 fr, which can meet the process requirements); before obtaining the finished product, fine grinding with clear water is carried out to make the surface roughness RMS < 0.5 nm. Through polishing processing, the surface shape can be well controlled, thus providing a high-quality processing reference surface for subsequent processing, meeting the optical gluing conditions, and facilitating the subsequent optical gluing and fixing process.

[0098] The first precision-machined lens, obtained after polishing, is removed from the adhesive tray, specifically by applying adhesive and removing it from the tray with a cutting tool. The first precision-machined lens is then cleaned using a mixture of acetone and alcohol to ensure a clean surface. Next, the part's dimensions, surface shape, and center thickness are inspected to ensure quality, preparing for the next process.

[0099] Step S600: Fix the first surface of the first fine-processed lens onto the optical disc using a pad, and perform fine processing on the overall shape of the second surface of the first fine-processed lens to form a spherical surface, thereby obtaining a plano-convex lens.

[0100] In the specific process, due to the ultra-thin edge of the first precision-machined lens, neither CNC polishing nor high-efficiency polishing can be used for direct mounting. Therefore, a 40mm pad is used (e.g., Figure 4 As shown, the first precision-machined lens is raised by fixing it with optical adhesive, so that the first precision-machined lens and the pad are formed as a whole for processing, thereby processing the second surface of the part to form a spherical (convex) surface.

[0101] The specific steps are as follows:

[0102] Please see Figure 4 A pre-fabricated pad 40 is prepared before processing the plano-convex lens. This allows the pre-fabricated pad to be directly used during the first fine-machining of the lens, facilitating the loading and unloading of the plate during plano-convex lens processing and saving turnaround time. The pad processing flow is as follows:

[0103] Step 1: Process the first surface of the blank pad. When processing the first surface, apply sealing wax to the plate, and process the surface shape to N≤0.2, ΔN≤0.2, and chamfer the edges to C0.2. This will meet the quality requirements of the adhesive surface when fixing it to the first precision-machined lens or adhesive plate.

[0104] Step 2: Fix the first side of the processing pad blank to the gluing tray with gluing adhesive. Apply gluing adhesive to the side with good surface shape, ensuring parallelism <30".

[0105] Step 3: Process the second side of the blank pad. When processing the second side, apply a sealing wax plate, ensuring the surface shape is N≤0.2 and ΔN≤0.2, and chamfer the edges: C0.2. This meets the quality requirements of the adhesive surface when subsequently fixing it to the first precision-machined lens or adhesive plate.

[0106] Therefore, the surface shape deviation between the two opposing surfaces of the processed pad and the photoresist tray is: N≤0.2, ΔN≤0.2, where N represents the number of aperture stops and ΔN represents the number of local aperture stops; the parallelism between the two opposing surfaces of the pad is less than 30″. This satisfies the photoresist fixing conditions between the pad and the photoresist tray, enabling stable photoresist fixing.

[0107] Please see Figure 5 A pre-processed optical adhesive, 30, is prepared. This optical adhesive disc 30 is mainly used for the first precision lens processing. The diameter of the optical adhesive disc is φ300mm, the surface shape requirement is 0.1fr (0.05λ@633nm), and the parallelism between the upper and lower surfaces is θ<1″. First, the lower surface of the optical adhesive disc blank is processed. Then, the optical adhesive on the upper surface of the optical adhesive disc blank is applied to the large disc, and processed until N≤0.5, ΔN≤0.5, and the parallelism of the disc is controlled to ≤30″. Then, the upper surface of the optical adhesive disc blank is processed again to form an optical adhesive disc that meets the requirements.

[0108] After the preliminary work is completed, step S600 specifically includes:

[0109] Step S610: Randomly check and record the actual thickness of the pad. The actual thickness of the pad is used to calculate the grinding amount when grinding the spherical surface of the first precision-machined lens.

[0110] Sampling and recording the quality of the pads helps to precisely control the grinding amount of each part during subsequent grinding processes. This allows the grinding thickness of each part to be adjusted according to the thickness of the corresponding pad, ensuring that the ground parts meet quality requirements. This is especially important during the finishing process, when machining the spherical surface of the first finishing lens, which requires achieving the final required dimensions. Therefore, high dimensional quality is required. By recording the quality of the pads and adjusting the machining amount during the final processing, stable control of the final dimensional quality can be achieved.

[0111] Step S620: Fix the first surface of the first precision-machined lens onto the pad with photoresist, wherein the first precision-machined lens is adsorbed onto the pad by tooling positioning during the photoresist process.

[0112] Please see Figure 6 The first precision-machined lens 21 and the photoresist surface of the pad 40 are wiped clean, and then photoresist is applied. The tooling 50 is used for positioning. In this embodiment, the tooling 50 includes a base plate 51 and a positioning plate 52, with the positioning plate 52 vertically mounted on the base plate 51. When the tooling 50 is in use, the pad 40 is placed on the base plate 51 and abuts against the positioning plate 52, and the first precision-machined lens 21 abuts against the positioning plate 52 and is lowered onto the pad 40.

[0113] When the first precision-machined lens 21 is applied to the pad 40 using the tooling 50, the first precision-machined lens 21 and the pad 40 are naturally attracted to each other, and stripes can be seen; after the connection, the joint of the optical adhesive is coated with glue.

[0114] Then, the optical adhesive of the first fine-processed lens 21 and the overall structure of the backing plate 40 are fixed onto the optical adhesive tray 30 for subsequent processing.

[0115] Step S630: Milling and grinding the overall shape of the first precision-machined lens to form a spherical surface with a predetermined size on the second surface of the first precision-machined lens. Among them, the height difference of the spherical surfaces of multiple first precision-machined lenses on the optical cement disc is less than 0.03 mm, and the spherical surface meets the preset surface shape requirement, so that the first precision-machined lens after milling and grinding reaches the fourth preset size, where the fourth preset size = standard size + fine grinding allowance.

[0116] In the specific process, milling the outer circular side surface of the first precision-machined lens to ensure the outer dimension. Opening a spherical surface on the second surface of the first precision-machined lens, and the spherical surface size is: +SR40. Controlling the height difference △t of the spherical surfaces of each part < 0.03, controlling the surface shape of the spherical surface to be -1 to -10 μm, grinding the spherical surface to make the size of the spherical surface reach 2.2 + 0.05 (the finished product size is 2 ± 0.1, so the fine grinding allowance is 0.2 mm). Performing spherical chamfering on the spherical surface through a chamfering die: 0.5 + 0.1 mm.

[0117] Step S640: Grinding the spherical surface of the first precision-machined lens to make the first precision-machined lens after grinding reach the upper limit value of the standard size and the surface shape of the spherical surface reach 0 to -2 μm.

[0118] Precision-grinding the spherical surface of the formed first precision-machined lens. The size of the first precision-machined lens after precision-grinding is the upper limit value of the standard size (for example, 2.1 mm, and the finished product standard size is 2 + 0.1 mm); the precision-grinding surface shape reaches 0 to -2 μm, and controlling the height difference △t of the spherical surfaces of each part ≤ 0.03

[0119] Step S650: Polishing the spherical surface of the first precision-machined lens after grinding to make the spherical surface aperture grade N = ±3, the surface shape requirement <lambda / 10@633nm, and the roughness < 0.5 nm, obtaining a plano-convex lens.

[0120] Polishing the spherical surface of the first precision-machined lens after grinding to obtain the required plano-convex lens. Making the surface quality of the spherical surface meet the high-precision quality requirements: N = ±3, (PV <lambda / 10@633nm) inspected by ZYGO disc, B = 10 - 5, and the roughness RMS < 0.5 nm. Through polishing, the surface shape can be well controlled.

[0121] After obtaining the plano-convex lens, cleaning the plano-convex lens, and the cleaning liquid uses an acetone + alcohol mixture to improve the cleaning efficiency.

[0122] After cleaning the plano-convex lens, removing the plano-convex lens from the backing plate. Specifically: Disassembling it from the backing plate with a part blade, paying attention not to scratch the plane. After cleaning the backing plate, storing it in the warehouse for use in the next processing. Conducting quality inspection on the removed plano-convex lens to ensure that all indicators meet the requirements.

[0123] Next, the plano-convex lens is trimmed to ensure proper center deviation and outer diameter. After trimming, the finished product is inspected to check whether all indicators meet the quality requirements.

[0124] In summary, the processing method for an ultra-thin plano-convex lens provided in this application utilizes existing conventional processing equipment, such as photoresist technology, CNC machining, high-efficiency polishing (high-level polishing on a disc), and classical polishing (low-level polishing on a disc), to control the surface shape and other dimensional accuracy requirements of the product. This achieves stable processing of the ultra-thin plano-convex lens and ensures its high-precision quality. Due to the ultra-thin thickness of the part, processing can easily cause stress changes in the product. This method eliminates residual stress by polishing one side of the product first, and subsequent finishing uses photoresist for fixation, avoiding uncontrollable and out-of-tolerance surface shape changes after polishing due to the introduction of residual stress. Furthermore, during processing, by photoresisting the part onto a backing plate, a series of processes such as fine grinding and polishing of thin-edged parts can be performed, resulting in high dimensional certainty. Through polishing, the surface shape can be well controlled.

[0125] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for manufacturing an ultrathin plano-convex lens, characterized in that, The ultra-thin plano-convex lens has a center thickness to diameter ratio of <1:10 and an edge thickness of <0.5mm. The method includes the following steps: Multiple blanks are fixed on a parallel disk, and the first surface of the blanks is rough ground to obtain a first rough ground blank. The first rough-grind blank is polished to release internal stress, resulting in a first rough-grind polished blank. The first surface of the first rough grinding and polishing blank is fixed on the parallel disk, and the second surface of the first rough grinding and polishing blank is rough ground to obtain the second rough grinding blank. The second rough grinding blank is polished to obtain a second rough grinding polished blank, in order to release the internal stress generated in the second roughing process; The second surface of the second rough polishing blank is fixed onto the optical adhesive disk, and the first surface of the second rough polishing blank is finely processed to obtain the first finely processed lens. The first surface of the first finely processed lens is fixed on the optical film disk by a pad, and the overall shape of the second surface of the first finely processed lens is finely processed to form a spherical surface, thereby obtaining a plano-convex lens. The pad is matched with the outline of the plano-convex lens; the surface shape deviation between the two opposing surfaces of the pad and the optical disc is: N≤0.2, ΔN≤0.2, where N represents the aperture number and ΔN represents the local aperture number; the parallelism between the two opposing surfaces of the pad is less than 30″. In the step of fixing multiple blanks on a light-reflecting disc and performing rough grinding on the first surface of the blanks to obtain the first rough-ground blank: Heat a parallel plate and apply rosin wax, wherein the weight ratio of rosin to white wax in the rosin wax is 1:1; The second surface of the blank is bonded to the parallel disc, and the edges of the blank are protected with adhesive.

2. The processing method of the ultrathin plano-convex lens as described in claim 1, characterized in that, In the step of fixing the blank on a parallel disk and performing rough grinding on the first surface of the blank to obtain a first rough-ground blank: The first surface of the blank is gradually polished so that the polished blank reaches the first preset size, and the height difference of multiple polished blanks on the parallel disc is no greater than 0.005mm, wherein the grit number of the polishing tool corresponding to the gradual polishing gradually increases.

3. The processing method of the ultrathin plano-convex lens as described in claim 2, characterized in that, In the step of fixing the first surface of the first rough-polished blank to the parallel disk and performing rough grinding on the second surface of the first rough-polished blank to obtain the second rough-polished blank: The first surface of the first rough polishing blank is fixed, and the second surface of the first rough polishing blank is gradually polished to obtain a second rough polishing blank. The second rough polishing blank reaches a second preset size, and the height difference of multiple second rough polishing blanks on the parallel disk is not greater than 0.005mm. The grit number of the polishing tool corresponding to the gradual polishing gradually increases.

4. The processing method of the ultrathin plano-convex lens as described in claim 3, characterized in that, In the step of polishing the second rough-ground blank to obtain the second rough-ground polished blank: The second rough grinding blank is polished in stages to obtain the first rough grinding polished blank, so that the second surface of the first rough grinding polished blank meets the preset planar surface shape requirements, wherein the polishing speed of the staged polishing process is gradually reduced.

5. The processing method of the ultrathin plano-convex lens as described in claim 4, characterized in that, In the step of fixing the second surface of the second rough grinding and polishing blank to the optical cement plate and performing finishing on the first surface of the second rough grinding and polishing blank to obtain the first finished lens: Fixing through the second surface of the second rough grinding and polishing blank, gradually grinding the first surface of the second rough grinding and polishing blank, so that the second rough grinding and polishing blank after grinding reaches the third preset size, and the height difference between multiple second rough grinding and polishing blanks after grinding on the optical cement plate is not greater than 0.005 mm. The mesh number of the grinding tool corresponding to the gradual grinding gradually increases, and the third preset size = standard size + convex surface machining allowance; Performing step-by-step polishing on the second rough grinding and polishing blank after grinding to obtain the first finished lens, so that the first surface of the first finished lens meets the preset flat surface shape requirement, and the polishing speed in the step-by-step polishing process gradually decreases.

6. The method for processing an ultrathin plano-convex lens as described in claim 5, characterized in that, In the step of fixing the first surface of the first finished lens to the optical cement plate through a backing plate and performing finishing on the overall shape of the second surface of the first finished lens to form a spherical surface and obtain a plano-convex lens: Optically cementing and fixing the first surface of the first finished lens to the backing plate, and adsorbing the first finished lens and the backing plate through tooling positioning during the optical cementing process; Milling the overall shape of the first finished lens, so that the second surface of the first finished lens forms a spherical surface with a predetermined size. The height difference between the spherical surfaces of multiple first finished lenses on the optical cement plate is less than 0.03 mm, the spherical surface meets the preset surface shape requirement, and the first finished lens after milling reaches the fourth preset size, where the fourth preset size = standard size + fine grinding allowance; Grinding the spherical surface of the first finished lens, so that the first finished lens after grinding reaches the upper limit value of the standard size and the surface shape of the spherical surface reaches 0 to -2 μm; Polishing the spherical surface of the first finished lens after grinding, so that the spherical surface aperture grade is N = ±3, the surface shape requirement <lambda / 10@633 nm, and the roughness < 0.5 nm to obtain a plano-convex lens.

7. The method for processing an ultrathin plano-convex lens as described in claim 6, characterized in that, The tooling includes: a bottom plate and a positioning plate, and the positioning plate is vertically arranged on the bottom plate; The backing plate is placed on the bottom plate and abuts against the positioning plate, and the first finished lens abuts against the positioning plate and is lowered onto the backing plate.

8. The method for processing an ultrathin plano-convex lens as described in claim 6, characterized in that, Before the step of optically cementing and fixing the first surface of the first finished lens to the backing plate and adsorbing the first finished lens and the backing plate through tooling positioning during the optical cementing process, it further includes: Randomly checking and recording the actual thickness of the backing plate, and the actual thickness of the backing plate is used to calculate the grinding amount when grinding the spherical surface of the first finished lens.

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