Processing method of ultrathin plano-convex lens

Abstract

The invention provides a processing method of an ultrathin plano-convex lens, which comprises the following steps: fixing a blank on a parallel disc, and carrying out rough grinding processing on a first surface to obtain a first rough grinding blank; the first rough grinding blank is polished, and a first rough grinding and polishing blank is obtained; the first surface of the first rough grinding and polishing blank is fixed to a parallel disc, and rough grinding machining is conducted on the second surface of the first rough grinding and polishing blank to obtain a second rough grinding blank; the second rough grinding blank is polished, and a second rough grinding and polishing blank is obtained; the second surface of the second rough grinding and polishing blank is fixed to an optical cement disc, and finish machining is conducted on the first surface of the second rough grinding and polishing blank to obtain a first finish machining lens; the first surface of the first finish machining lens is fixed to an optical cement disc through a base plate, finish machining is carried out on the overall appearance of the first finish machining lens to form a spherical surface, and the plano-convex lens is obtained. The problem that an existing ultra-thin plano-convex lens part is thin in size and prone to deformation, and consequently products do not reach the standard is solved.

Description

Technical Field

[0001] The present application relates to the technical field of optical parts processing, and more specifically, to a processing method of an ultra-thin plano-convex lens. Background Art

[0002] Among various optical lenses, plano-convex lenses are needed. One side (first surface) of the plano-convex lens is a plane and the other side (second surface) is a convex surface (spherical surface). Plano-convex lenses have a positive focal length and are usually used to narrow light beams, reduce focal length, or magnify images. In order to reduce spherical aberration, when a plano-convex lens is used to focus a collimated light beam, the light beam is incident on the convex surface of the lens; when it is used to collimate a point light source, the light beam is incident on a plane. Plano-convex lenses focus light into a point and are often used for aiming and focusing monochromatic light sources. The ultra-thin plano-convex lens is a special-sized plano-convex lens. The ultra-thin plano-convex lens means that the ratio of the center thickness to the diameter of the lens is less than 1:10, and the thickness of the edge of the lens is less than 0.5mm (the edge is thinner).

[0003] In the process of processing ultra-thin plano-convex lenses, it is usually necessary to bond and fix the parts to parallel plates for grinding, polishing and other processes. Parts usually use rosin wax as an adhesive, which exerts tension on the parts during bonding. After the parts are polished to the lower plate, due to the effect of internal stress, the surface shape tends to become concave, so the front shape of the lower plate needs to be convex, so as to compensate for the surface shape changes caused by the tension of the rosin wax. However, when the existing processing equipment requires the processing surface to be flat, it can often only guarantee flat surface processing, and it is not easy to guarantee the processing of convex surface shape, resulting in ultra-thin plano-convex lens parts failing to meet high-precision quality requirements during the processing process.

[0004] Therefore, the prior art still needs to be improved and developed. Summary of the invention

[0005] The purpose of the present application is to provide a method for processing an ultra-thin plano-convex lens, which solves the problem that the existing ultra-thin plano-convex lens parts cannot meet the high-precision quality requirements due to their thin size and easy deformation during the processing.

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

[0007] The present application provides a method for processing an ultra-thin plano-convex lens, comprising the steps of:

[0008] Fixing a plurality of blanks on the parallel disks, and performing rough grinding on the first surface of the blanks to obtain first rough-ground blanks;

[0009] Polishing the first roughly ground blank to release internal stress, thereby obtaining a first roughly ground and polished blank;

[0010] Fixing the first surface of the first roughly ground and polished blank to the parallel disk, and roughly grinding the second surface of the first roughly ground and polished blank to obtain a second roughly ground blank;

[0011] Polishing the second roughly ground blank to obtain a second roughly ground and polished blank;

[0012] The second surface of the second roughly ground and polished blank is fixed to the optical plastic disc, and the first surface of the second roughly ground and polished blank is finely processed to obtain a first finely processed lens;

[0013] The first surface of the first finely processed lens is fixed on the optical plastic disc through a pad, and the overall shape of the second surface of the first finely processed lens is finely processed to form a spherical surface to obtain a plano-convex lens.

[0014] In an optional embodiment, in the step of fixing the blank on the 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 ground so that the ground blank reaches a first preset size, and the height difference of the multiple ground blanks on the parallel disk is no more than 0.005 mm, wherein the mesh number of the grinding tool corresponding to the step-by-step grinding is gradually increased.

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

[0017] The first surface of the first rough-ground polishing blank is fixed, and the second surface of the first rough-ground blank is gradually ground to obtain a second rough-ground blank, the second rough-ground blank reaches a second preset size, and the height difference of multiple second rough-ground blanks on the parallel disk is not greater than 0.005mm, wherein the mesh number of the grinding tool corresponding to the step-by-step grinding gradually increases.

[0018] In an optional embodiment, in the step of polishing the second roughly ground blank to obtain the second roughly ground and polished blank:

[0019] The second roughly ground blank is polished step by step to obtain a first roughly ground and polished blank, so that the second surface of the first roughly ground and polished blank meets the preset plane surface shape requirement, wherein the polishing speed of the step-by-step polishing process is gradually reduced.

[0020] In an optional embodiment, in the step of fixing the second surface of the second roughly ground and polished blank to the optical plastic disc and fine-machining the first surface of the second roughly ground and polished blank to obtain the first fine-machining 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 ground and polished blank so that the second rough ground and polished blank after grinding reaches the third preset dimension, and the height difference of multiple second rough ground and polished blanks on the optical cementing plate is not greater than 0.005 mm, wherein the mesh number of the grinding tool corresponding to the gradual grinding gradually increases, and the third preset dimension = standard dimension + convex surface machining allowance;

[0022] Perform step-by-step polishing on the second rough ground and polished 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, wherein 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 a 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, wherein during the optical cementing process, the first precision-machined lens is adsorbed to the backing plate through tooling positioning;

[0025] Milling and grinding the overall shape of the first precision-machined lens so that the second surface of the first precision-machined lens forms a spherical surface with a predetermined dimension. Among them, 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 dimension, wherein the fourth preset dimension = standard dimension + precision 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 dimension 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 is <lambda / 10@633nm, and the roughness is <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 number of apertures and ΔN represents the number of local apertures;

[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 bottom plate and abuts against the positioning plate, and the first fine-machined lens abuts against the positioning plate and is lowered onto the pad.

[0033] In an optional embodiment, before the first surface optical glue of the first fine-machined lens is fixed on the pad, wherein before the step of adsorbing the first fine-machined lens to the pad by positioning the tool during the optical glue process, the step further includes:

[0034] The actual thickness of the backing plate is randomly inspected and recorded. The actual thickness of the backing plate is used to calculate the grinding amount when grinding the spherical surface of the first fine-machined lens.

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

[0036] Heat the parallel plates 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 disk, and the edge of the blank is coated with glue for protection.

[0038] The beneficial effect of the processing method of an ultra-thin plano-convex lens provided by the present application is at least that: firstly, the first surface of the blank is roughly ground to obtain a first roughly ground blank, and the first roughly ground blank is polished to release the internal stress to obtain a first roughly ground and polished blank, thereby effectively reducing the internal stress generated by the part in the first roughing process. Then, the second surface of the first roughly ground and polished blank is roughly ground to obtain a second roughly ground blank, and the second roughly ground and polished blank is polished to obtain a second roughly ground and polished blank to release the internal stress generated in the second roughing process. Since the internal stress is released, the deformation effect caused by the internal stress in the roughing of the blank is greatly reduced in the subsequent fine processing. Then, a light glue disk is used for light glue fixation, and the first surface of the second roughly ground and polished blank is finely processed to obtain a first finely processed lens. In this way, the light glue fixation is replaced by the fixing method of adhesives such as rosin wax during the fine processing process, thereby avoiding the problem of deformation of the finely processed parts caused by the adhesive generating tension on the parts. Finally, the backing plate is fixed on the optical glue disk, and the second surface of the first fine-processing lens is fine-processed to obtain a plano-convex lens; in this way, not only the deformation caused by tension is avoided by fixing with optical glue instead of fixing with adhesives such as rosin wax, but also the backing plate and the first fine-processing lens are fixed as a whole, thereby increasing the thickness of the workpiece, and thus the structural strength of the first fine-processing lens during processing is enhanced by the backing plate, especially the thickness of the thinner edge of the first fine-processing lens is increased, so that the thinner edge of the first fine-processing lens is stably supported during the processing, so the thinner edge of the first fine-processing lens is not easily deformed or damaged during the fine-processing process. This ensures that the optical lens meets the high-precision quality requirements during the processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0040] Figure 1 A flowchart of the main steps of a method for processing an ultra-thin plano-convex lens provided in an embodiment of the present application;

[0041] Figure 2 A flowchart of detailed steps of a method for processing an ultra-thin plano-convex lens provided in an embodiment of the present application;

[0042] Figure 3 A schematic diagram of the dimensions of a plano-convex lens from a blank to a finished product according to a method for processing an ultra-thin plano-convex lens provided in an embodiment of the present application;

[0043] Figure 4 A schematic structural diagram of a backing plate used in a method for processing an ultra-thin plano-convex lens provided in an embodiment of the present application;

[0044] Figure 5 A schematic structural diagram of an optical plastic disc used in a method for processing an ultra-thin plano-convex lens provided in an embodiment of the present application;

[0045] Figure 6 A schematic diagram of the principle of using a tool in a method for processing an ultra-thin plano-convex lens provided in an embodiment of the present application;

[0046] Figure 7 A distribution diagram of the arrangement positions of the first fine-machined lens on a photoresist disk in a method for machining an ultra-thin plano-convex lens provided in an embodiment of the present application.

[0047] Among them, the reference numerals in the figure are:

[0048] 10. Blank; 20. Plano-convex lens; 21. First finishing lens; 30. Optical plastic disc; 40. Backing plate; 50. Tooling; 51. Base plate; 52. Positioning plate. DETAILED DESCRIPTION

[0049] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0050] It should be noted that when a component is referred to as being "fixed on" or "disposed on" another component, it may be directly or indirectly located on the other component. When a component is referred to as being "connected to" another component, it may be directly or indirectly connected to the other component. The directions or positions indicated by the terms "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are based on the directions or positions shown in the accompanying drawings and are only for the convenience of description and cannot be understood as limitations on the present technical solution. The terms "first" and "second" are only used for the convenience of description and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features. "Multiple" means two or more, unless otherwise clearly and specifically defined.

[0051] The professional terms related to this embodiment are explained as follows:

[0052] Surface shape: PV (Peak to valley), surface shape requirement is also called peak to valley value, which is a common indicator of optical surface shape quality. It refers to the height difference between the highest point and the lowest point within the sampling range (based on 2D contour line or 3D data map), after removing the reference plane. The PV value is in physical length units. Based on the required reference plane, the maximum deviation range of all pixels directly reflects the processing quality of the current optical surface. According to the experience of long-term optical testing in the past, the PV value and another important surface shape indicator RMS often maintain a certain proportional relationship, generally around 2:1.

[0053] Pad: Used to support the tooling for machining convex surfaces, with high parallel accuracy, reaching the second level.

[0054] Rosin wax: used to bond and fix optical parts when processing their surface.

[0055] Optical bonding: A method of bonding complex optical parts. Since there is no medium between the bonding surfaces, the optical properties remain unchanged. Compared with the adhesive layer bonding method, the optical bonding method has higher mechanical strength and stable performance that can be maintained for decades; it has small deformation and good cold and heat resistance. However, the optical bonding process requires high manufacturing precision of the optical bonding surface.

[0056] The requirements of the photo-bonding process for the photo-bonding surface are as follows: Photo-bonding is a process that relies on the attraction between molecules to tightly bond two surfaces together. The attraction between molecules on the surfaces is a statistical physical phenomenon. It does not work on the entire photo-bonding surface, but works between the microscopic peaks or troughs of the two surfaces. Since the peaks and troughs are small and dense, the statistical area that produces molecular attraction is quite large, enough to bond the two surfaces together. In addition, the photo-bonding process first applies pressure to the edge of the photo-bonded part to bond that part first. In the area near the interface between the photo-bonded and un-photo-bonded parts, the molecular attraction causes deformation, causing the un-photo-bonded surfaces that are in contact with each other to reach the range of molecular attraction, so that the photo-bonding bonding surface gradually expands until the entire bonding surface is bonded together.

[0057] The intermolecular forces can be expressed as follows:

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

[0059] Generally speaking, when r = 10-3μm ~ 10-4μm, gravity will be exhibited, that is, the distance between the two photoresist surfaces can only show the intermolecular attraction effect when it is within the range of 0.001μm ~ 0.01μm. This is the error requirement of the photoresist surface:

[0060]

[0061] Obviously, it is difficult to machine such a high-precision polished surface, and even if it is machined, it is difficult to detect. The amount of deformation of the part due to a slight change in the surrounding medium will be 10 orders of magnitude larger than this error. The thickness of the optical glue parts, the aperture pairing of the optical glue parts, and the consistency of the outer diameter are selected according to the technical requirements. The aperture size is N≤0.2, ΔN≤0.2, and the surface rust level is not less than 3×0.16 specified in the national standard GB1182-89; the optical glue parts should be placed at a constant temperature of 20℃±1℃ for several hours to make the temperature of each part uniform.

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

[0063] High-efficiency polishing: Adopt quasi-spherical center high-speed polishing method, increase the machine tool spindle speed, increase the polishing pressure, and maximize the processing efficiency to produce lenses that meet quality requirements.

[0064] Classical polishing: Classical polishing is a traditional glass cold processing method. The polishing machine uses friction wheel transmission, the spindle speed is low, and pressure is applied by a flat swinging tripod, and the pressure is adjusted by the load weight.

[0065] See also Figure 1 , Figure 3 , this embodiment proposes a method for processing an ultra-thin plano-convex lens, which is used for processing ultra-thin plano-convex lens parts, and ensures that the processed plano-convex lens 20 meets high-precision quality requirements. For the convenience of structural description, the plano-convex lens 20 (ultra-thin plano-convex lens type) has a side that forms a plane as the first surface, and a side that forms a convex surface (spherical surface) as the second surface (the intermediate transition half-cost parts formed in the molding 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 reach: the surface shape requirement of the first surface (plane) is PV<Lambda / 10@633nm; the effective light-clearance 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-clearance diameter of the second surface is Φ20mm; the second surface roughness 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 (such as the outer circular side surface).

[0066] See also 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 surface size SR 40mm, edge thickness 0.5mm, as an example for specific description.

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

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

[0069] Step S100: fix a plurality of blanks on parallel plates, and perform rough grinding on a first surface of the blanks to obtain a first rough-ground blank.

[0070] In a specific process, after the blank is fixed by bonding through parallel disks, the first surface of the blank is rough-machined.

[0071] Step S100 of this embodiment specifically includes:

[0072] Step S110, heating the parallel disk and applying rosin wax, wherein the weight ratio of rosin to white wax in the rosin wax is 1:1.

[0073] Step S120, bonding the second surface of the blank to the parallel disk, and applying glue to protect the edge of the blank.

[0074] In the above process, first wipe one of the surfaces of the blank clean and use this surface as the second surface, then heat the parallel disk, apply rosin wax, and the rosin wax formed by the ratio of rosin to white wax of 1:1 ensures the bonding stability, and adhere the wiped clean second surface to the parallel disk, and finally apply glue for protection.

[0075] Step S130, gradually grinding the first surface of the blank so that the ground blank reaches a first preset size, and the height difference of the multiple ground blanks on the parallel disk is no more than 0.005 mm, wherein the mesh number of the grinding tool corresponding to the step-by-step grinding gradually increases.

[0076] In the specific process, the first preset size is 2.55+0.01mm. Therefore, it is necessary to erase about 0.04-0.05mm. Grinding can be performed twice, and the thickness of the grinding is the same in the two grindings. The coarseness of the grinding tools used in the two grindings is different. The mesh number of the grinding tool used in the first grinding is 303#, and the mesh number of the grinding tool used in the second grinding is 303.5#. Therefore, the more times the step-by-step grinding is performed, the finer the grinding tool used, so that the coarser grinding tool can provide grinding efficiency, and the finer grinding tool is used to improve the brightness and fineness. While improving efficiency, the product quality is guaranteed, and the height difference of multiple polished blanks on the parallel disk can be controlled at Δt≤0.005mm.

[0077] Step S200: polishing the first roughly ground blank to release internal stress, thereby obtaining a first roughly ground and polished blank.

[0078] In the specific process, the first surface after grinding is high-polished, and the spindle speed of the machine tool is increased to make the first surface polished. Ultra-thin plano-convex lenses will have residual stress introduced during processing due to their ultra-thin thickness. By polishing one side of the first roughly ground blank, the residual stress caused by the change in product structure is eliminated to avoid part deformation due to stress in subsequent processing.

[0079] After the first surface of the blank is roughly processed, a first roughly ground and polished blank is obtained. The first roughly ground and polished blank is removed from the parallel disk by heating the parallel disk and cleaned.

[0080] Step S300: fix the first surface of the first roughly ground and polished blank onto the parallel disk, and perform rough grinding on the second surface of the first roughly ground and polished blank to obtain a second roughly ground blank.

[0081] This step is to perform rough machining on the second surface of the blank by means of the parallel disk. Therefore, step S300 specifically includes:

[0082] Step S310: Use the polished first surface of the first rough-ground and polished blank as a bonding surface, apply glue dots on the bonding surface, and bond it to the parallel disk.

[0083] In the specific process, the glue point is rosin glue point, and the diameter of the parallel plate is Φ183mm, so each plate can hold 54 pieces of the first rough grinding and polishing blanks. After the plate is placed, the edge of the first rough grinding and polishing blank is coated with glue for protection (refer to Figure 7 distribution in ).

[0084] Step S320, fix the first surface of the first rough-ground and polished blank, and gradually grind the second surface of the first rough-ground blank to obtain a second rough-ground blank, the second rough-ground blank reaches a second preset size, and the height difference of the multiple second rough-ground blanks on the parallel disk is not greater than 0.005 mm, wherein the mesh number of the grinding tool corresponding to the gradual grinding gradually increases.

[0085] In the specific process, the second preset size can be 2.38+0.02mm, which is the center thickness size. The gradual grinding process can be divided into three steps. The first step is to use a coarser grinding tool (280# sand) to grind off 0.1mm; the second step is to use a slightly finer grinding tool (303# sand) to grind off 0.05mm; the third step is to use the finest grinding tool (303.5# sand) to grind off 0.02mm. Therefore, the thickness of the part ground by a coarser grinding tool is large, and the thickness of the part ground by a finer grinding tool is small. Then the thickness of the part ground gradually decreases. When the thickness of the part is relatively large, it can be ground quickly to improve the processing efficiency. When the thickness of the part gradually decreases, the amount of grinding also gradually decreases to avoid deformation of the part caused by excessive pressure during the grinding process, making the part size more controllable and improving the processing quality of the product. Finally, fine grinding can ensure that the center thickness of the second coarse-ground blank is 2.38+0.02mm, so that the height difference of each second coarse-ground blank obtained by processing can be controlled within Δt≤0.005mm. In this way, the quality of the second coarse-ground blank on the entire parallel disk can be controlled within the required range, thereby improving the yield rate.

[0086] Step S400: polishing the second roughly ground blank to obtain a second roughly ground and polished blank.

[0087] In the specific process, the second rough-ground blank is polished step by step to obtain the first rough-ground and polished blank, so that the second surface of the first rough-ground and polished 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-ground blank, not only a high-precision machining 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-speed polishing to achieve detection polishing, so that the disk quality reaches N≤3fr; the speed of disk high-speed polishing is fast, and lenses meeting the quality requirements are polished at the highest possible processing efficiency. Then, perform disk low-speed polishing. The speed of disk low-speed polishing is slower than that of disk high-speed polishing. Disk low-speed polishing is used for polishing, and the polishing pressure used is small. Therefore, the influence on the deformation of the second rough-ground blank is small, and the polishing quality can be well guaranteed. The first rough-ground and polished 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, grind it finely with clear water to make the surface roughness RMS < 0.5nm, so as to provide a machining reference surface that meets high quality for the subsequent processing. Thus, the optical cementing condition is satisfied, which is convenient for the subsequent optical cementing and fixing process.

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

[0090] Step S500: Fix the second surface of the second rough-ground and polished blank to the optical cementing disk, and perform finishing on the first surface of the second rough-ground and polished 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-ground and polished blank, and gradually grind the first surface of the second rough-ground and polished blank so that the polished second rough-ground and polished blank reaches the third preset size, and the height difference between multiple polished second rough-ground and polished blanks on the optical cementing 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 machining 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 bonding. It is optically bonded and fixed to the optical bonding plate, and still 54 pieces / Φ183 plate are used, so that the 54 second rough grinding and polishing blanks on the whole plate can be processed synchronously, thus improving the efficiency of mass production. After loading the plate, the edges of the second rough grinding and polishing blanks are coated with glue for protection.

[0095] During the process of gradually grinding the first surface of the second rough grinding and polishing blank, it can be divided into 2 steps. In the first step of grinding, a coarser grinding tool (303# sand) is used to grind off 0.08 mm; in the second step of grinding, 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 the processing pressure during the grinding process can be effectively controlled, so the dimensional controllability during the processing is ensured. 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 of each second rough grinding and polishing blank after processing can be controlled within Δt ≤ 0.005 mm. In this way, the quality of the parts on the entire parallel plate can be controlled within the required range, and the yield rate is improved.

[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 use high-speed disk polishing. The polishing speed of high-speed disk polishing is fast, and rapid rotation is realized for detection polishing, so that the disk quality reaches N ≤ 3 fr. Then perform low-speed disk polishing. 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 value 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, grind it finely with clear water to make the surface roughness RMS < 0.5 nm. Through polishing, the surface shape can be well controlled, thus providing a high-quality processing reference surface for subsequent processing, meeting the optical bonding conditions, and facilitating the subsequent optical bonding and fixing process.

[0098] Remove the first finely processed lens obtained after polishing from the optical plastic plate, specifically by applying glue and removing the plate with a blade. Clean the first finely processed lens after removing the plate, using a mixture of acetone and alcohol as the cleaning fluid to ensure that the surface of the first finely processed lens is clean, and then inspect the part size, surface shape and center thickness to ensure that the quality is qualified, and prepare for the next process.

[0099] Step S600: fix the first surface of the first fine-machined lens on the optical disk through a pad, and fine-machine the overall shape of the second surface of the first fine-machined lens to form a spherical surface to obtain a plano-convex lens.

[0100] In the specific process, since the edge of the first finely processed lens is ultra-thin, it is impossible to directly clamp it by using CNC polishing or high-efficiency polishing, so a pad 40 (such as Figure 4 The first finishing lens is raised by fixing it with optical glue (as shown in the figure), so that the first finishing lens and the pad form a whole for processing, thereby processing the second surface of the part to form a spherical surface (convex surface).

[0101] The specific steps are as follows:

[0102] See also Figure 4 , the pad 40 is pre-processed, and the pad is processed before the plano-convex lens is processed. In this way, when the first fine-processing lens is processed, the processed pad can be directly used, so as to facilitate the upper and lower plates in the process of processing the plano-convex lens, saving circulation time. The processing flow of the pad is:

[0103] Step 1: Process the first side of the backing plate blank. When processing the first side, use sealing wax to plate it, and process the surface shape to N≤0.2, ΔN≤0.2, and edge chamfer: C0.2. This will meet the quality requirements of the optical glue surface when it is subsequently fixed with the first finely processed lens or optical glue plate.

[0104] Step 2: Fix the first side of the processed pad blank to the polishing plate with polishing glue. Put the polishing glue on the surface with good surface shape to ensure the parallelism is less than 30〃.

[0105] Step 3: Process the second side of the backing plate blank. When processing the second side, use wax sealing to plate, and the surface shape is N≤0.2, ΔN≤0.2, and the edge chamfer: C0.2. This will meet the quality requirements of the optical glue surface when fixing with the first finely processed lens or optical glue plate.

[0106] Therefore, the surface deviations between the two opposite surfaces of the processed pad and the optical adhesive disc are: N≤0.2, ΔN≤0.2, where N represents the aperture number and ΔN represents the local aperture number; the parallelism of the two opposite surfaces of the pad is less than 30". In this way, the optical adhesive fixing conditions are met between the pad and the optical adhesive disc, and stable optical adhesive fixing can be achieved.

[0107] See also Figure 5 , pre-process the optical resin, 30, the optical resin disc 30 is mainly used for processing the first fine-machining lens, the diameter of the optical resin disc is φ300mm, the surface shape requirement is 0.1fr (0.05λ@633nm), and the parallelism between the upper surface and the lower surface is θ<1″. Firstly process the lower surface of the optical resin disc blank, and put the optical resin of the upper surface of the optical resin disc blank on the large disc, and process it to N≤0.5, ΔN≤0.5, and the parallelism of the disc is controlled to be ≤30″. Then process the upper surface of the optical resin disc blank to form an optical resin disc that meets the requirements.

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

[0109] Step S610: spot check the actual thickness of the backing plate and record it. The actual thickness of the backing plate is used to calculate the grinding amount when grinding the spherical surface of the first fine-machined lens.

[0110] Randomly checking the pads for quality records will help to finely control the grinding amount of each part during the subsequent grinding process, so that the grinding thickness of each part can be adjusted according to the thickness of the corresponding pad, so that the parts obtained after grinding meet the quality requirements. Especially in the fine machining process, when machining the spherical surface of the first fine-machined lens, the final required size needs to be achieved, so high requirements are placed on the dimensional quality. By recording the quality of the pads and adjusting the machining amount during the final machining process, stable control of the final dimensional quality can be achieved.

[0111] Step S620, fix the first surface of the first fine-machined lens on the backing plate with optical glue, wherein the first fine-machined lens and the backing plate are adsorbed by tooling positioning during the optical glue process.

[0112] See also Figure 6 , clean the optical glue surface of the first fine-machined lens 21 and the backing plate 40, then perform optical glue, and use the tooling 50 to position. In this embodiment, the tooling 50 includes: a bottom plate 51 and a positioning plate 52, and the positioning plate 52 is vertically arranged on the bottom plate 51; when the tooling 50 is in use, the backing plate 40 is placed on the bottom plate 51 and abuts against the positioning plate 52, and the first fine-machined lens 21 abuts against the positioning plate 52 and is lowered onto the backing plate 40.

[0113] When the first fine-machined lens 21 is optically glued to the backing plate 40 by the tooling 50, the first fine-machined lens 21 and the backing plate 40 are naturally adsorbed and stripes can be seen; after connection, the optical glue connection seam is coated with glue.

[0114] Then, the optical glue of the first fine-processed lens 21 and the overall structure of the backing plate 40 are fixed to the optical glue 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 between the spherical surfaces of multiple first precision-machined lenses on the optical cementing disc is less than 0.03 mm, and the spherical surface meets the preset surface shape requirements, 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 shape size. 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 between the spherical surfaces of each part to be less than 0.03, and 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). Chamfering 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 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.

[0118] Precision grinding the spherical surface of the already 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 ground surface shape reaches 0 to -2 μm, and controlling the height difference △t between the spherical surfaces of each part to be ≤ 0.03

[0119] Step S650: Polishing 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 is <lambda / 10@633nm, the roughness is < 0.5 nm, and a plano-convex lens is obtained.

[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) ZYGO disc inspection, B = 10 - 5, 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 using a mixed solution of acetone + alcohol as the cleaning liquid 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] Then the plano-convex lens is edge cut to ensure the center deviation and outer diameter. After edge cutting, the finished product is tested to check whether all indicators meet the quality requirements.

[0124] In summary, the present application provides a method for processing an ultra-thin plano-convex lens, which uses existing traditional processing equipment, such as optical glue technology, CNC numerical control, high-efficiency polishing (high polishing of the disc), classical polishing (low polishing of the disc), etc. to control the surface shape and other dimensional accuracy requirements of the product, thereby achieving stable processing of the ultra-thin plano-convex lens and ensuring the high-precision quality requirements of the ultra-thin plano-convex lens. Since the thickness of the parts is ultra-thin, it is very easy to cause stress changes in the product after processing. This method can eliminate residual stress by first polishing one side of the product, and the subsequent fine processing is fixed with optical glue to avoid the problem of uncontrollable and out-of-tolerance shape changes of the product after polishing due to the introduction of residual stress. Moreover, during the processing, by optically gluing the parts to the pad, a series of processes such as fine grinding and polishing can be performed on the parts with thin edges, and the processing size is highly certain. Through polishing processing, the surface shape can be well controlled.

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

Claims

1. A method for processing an ultra-thin plano-convex lens, characterized in that: The method comprises the steps of: Fixing a plurality of blanks on the parallel disks, and performing rough grinding on the first surface of the blanks to obtain first rough-ground blanks; Polishing the first roughly ground blank to release internal stress, thereby obtaining a first roughly ground and polished blank; Fixing the first surface of the first roughly ground and polished blank onto a parallel plate, and performing rough grinding on the second surface of the first roughly ground and polished blank to obtain a second roughly ground blank; Polishing the second roughly ground blank to obtain a second roughly ground and polished blank; Fixing the second surface of the second roughly ground and polished blank onto a photoresist plate, and fine-machining the first surface of the second roughly ground and polished blank to obtain a first fine-machining lens; The first surface of the first finely processed lens is fixed on the optical plastic disc through a pad, and the overall shape of the second surface of the first finely processed lens is finely processed to form a spherical surface to obtain a plano-convex lens.

2. The method for processing an ultra-thin plano-convex lens according to claim 1, characterized in that: In the step of fixing the blank on the parallel disk and rough grinding the first surface of the blank to obtain a first rough-ground blank: The first surface of the blank is gradually ground so that the ground blank reaches a first preset size, and the height difference of the multiple ground blanks on the parallel disk is no more than 0.005 mm, wherein the mesh number of the grinding tool corresponding to the step-by-step grinding is gradually increased.

3. The method for processing an ultra-thin plano-convex lens according to claim 2, characterized in that: In the step of fixing the first surface of the first roughly ground and polished blank onto a parallel disk and roughly grinding the second surface of the first roughly ground and polished blank to obtain a second roughly ground blank: The first surface of the first rough-ground and polished blank is fixed, and the second surface of the first rough-ground blank is gradually ground to obtain a second rough-ground blank, the second rough-ground blank reaches a second preset size, and the height difference of the multiple second rough-ground blanks on the parallel disk is not greater than 0.005 mm, wherein the mesh number of the grinding tool corresponding to the step-by-step grinding gradually increases.

4. The method for processing an ultra-thin plano-convex lens according to claim 3, characterized in that: In the step of polishing the second roughly ground blank to obtain a second roughly ground and polished blank: The second roughly ground blank is polished step by step to obtain a first roughly ground and polished blank, so that the second surface of the first roughly ground and polished blank meets the preset plane surface shape requirement, wherein the polishing speed of the step-by-step polishing process is gradually reduced.

5. The method for processing an ultra-thin plano-convex lens according to claim 4, characterized in that: In the step of fixing the second surface of the second roughly ground and polished blank to the optical plastic disc and fine-machining the first surface of the second roughly ground and polished blank to obtain a first finely-machined lens: The second rough-ground and polished blank is fixed by the second surface, and the first surface of the second rough-ground and polished blank is gradually ground, so that the second rough-ground and polished blank after grinding reaches a third preset size, and the height difference of the plurality of second rough-ground and polished blanks after grinding on the optical plastic disc is not greater than 0.005 mm, wherein the mesh number of the grinding tool corresponding to the step-by-step grinding is gradually increased, and the third preset size = standard size + convex surface machining allowance; The second roughly ground and polished blank is polished in steps to obtain a first finely processed lens, so that the first surface of the first finely processed lens meets the preset plane surface shape requirement, wherein the polishing speed of the step-by-step polishing process is gradually reduced.

6. The method for processing an ultra-thin plano-convex lens according to claim 5, characterized in that: In the step of fixing the first surface of the first precision-machined lens on a cemented disk through a 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 obtaining a plano-convex lens: Optically cement and fix the first surface of the first precision-machined lens on the backing plate, and during the optical cementing process, position the first precision-machined lens and the backing plate to adsorb each other through a tooling. Milling 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 cemented disk is less than 0.03 mm, and the spherical surface meets the preset surface shape requirements, so that the first precision-machined lens after milling reaches the fourth preset size, where the fourth preset size = standard size + fine grinding allowance. Polishing the spherical surface of the first precision-machined lens so that the first precision-machined lens after polishing 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 precision-machined lens after polishing so that the spherical surface aperture grade is N = ±3, the surface shape requirement is <lambda / 10@633 nm, and the roughness is < 0.5 nm to obtain a plano-convex lens.

7. The method for processing an ultra-thin plano-convex lens according to claim 6, wherein: The backing plate matches the outer contour of the plano-convex lens. The surface shape deviation between the two opposite surfaces of the backing plate and the cemented disk is: N ≤ 0.2, ΔN ≤ 0.2, where N represents the number of apertures and ΔN represents the number of local apertures. The parallelism of the two opposite surfaces of the backing plate is less than 30〃.

8. The method for processing an ultra-thin plano-convex lens according to claim 6, wherein: 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 precision-machined lens abuts against the positioning plate and is lowered onto the backing plate.

9. The method for processing an ultra-thin plano-convex lens according to claim 6, wherein: Before the step of optically cementing and fixing the first surface of the first precision-machined lens on the backing plate and positioning the first precision-machined lens and the backing plate to adsorb each other through a tooling during the optical cementing process, it further includes: Randomly inspect and record 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 precision-machined lens.

10. The method for processing an ultra-thin plano-convex lens according to claim 1, wherein: In the step of fixing multiple blanks on a cemented disk and performing rough grinding on the first surface of the blanks to obtain the first rough-ground blank: Heat the parallel disk and apply rosin wax, where the weight ratio of rosin to white wax in the rosin wax is 1:

1. Bond the second surface of the blank to the parallel disk and apply glue for protection at the edge of the blank.

Images