Optical aspheric lens polishing and grinding integrated processing device and method

Abstract

The application discloses a kind of optical aspheric lens repair polishing integrated processing device and method, the device includes profiling tool, liquid supply pump, polishing liquid tank, adsorption fixture, rotating platform, rotating motor and three-axis motion platform.The present application designs corresponding profiling tool according to the surface profile curve of target aspheric lens, first by contact processing, quickly remove material, obtain the surface profile close to aspheric lens, then continue to use the profiling tool to use shear thickening polishing method to the aspheric lens after profiling is carried out non-contact polishing, obtain high quality high surface profile precision aspheric lens, while due to not needing to replace processing tool and processing equipment, can greatly improve processing efficiency.The profiling tool designed in the present application obtains better aspheric lens surface profile precision with higher material removal rate in the profiling stage, and in the polishing stage, non-contact mode is used, and high surface profile precision and surface quality can be adaptively realized.

Description

Technical Field

[0001] This invention belongs to the field of precision / ultra-precision machining, and specifically relates to an integrated processing device and method for repairing and polishing optical aspherical lenses. Background Technology

[0002] Compared to traditional spherical lenses, aspherical lenses offer advantages such as aberration elimination and a wider field of view. In an optical system, one aspherical lens can achieve the effect of three to four spherical lenses, enabling smaller and lighter optical components, thus reducing instrument weight and cost. Therefore, aspherical lenses are widely used in military fields such as satellites and missile seekers, as well as in optical, medical, and industrial fields such as cameras, X-ray lenses, and lithography lenses.

[0003] With the current trend towards miniaturization and precision in equipment, the requirements for the surface quality and shape accuracy of aspherical lenses are becoming increasingly stringent, often demanding nanometer-level surface roughness and micrometer-level shape accuracy. However, aspherical lenses have complex shapes and varying curvatures at different points on their surface. Ensuring both shape accuracy and high-quality surface quality has become a key challenge in the manufacturing and processing of aspherical lenses. While traditional glass molding technology can form aspherical lenses in one step, this technology relies heavily on high-precision molds, and residual stress inevitably arises during the molding process, affecting shape accuracy. Since the processing technology for spherical lenses is now very mature, the first step in mass production is to process the side of the aspherical lens that is closest to a sphere. Subsequent shaping and polishing processes are then used to obtain a high-quality aspherical lens. The shaping process requires significant material removal to quickly achieve the aspherical shape; while the polishing process primarily removes surface damage from the previous process, reduces surface roughness, and further improves shape accuracy, resulting in a relatively low material removal rate. The two processes have different focuses, therefore, the production of high-quality aspherical lenses requires switching between multiple processing equipment and methods, which increases equipment costs and reduces efficiency. Therefore, researching a simple and efficient integrated polishing and finishing equipment and method is of great significance for the mass production of high-quality aspherical lenses.

[0004] Chinese patent CN202111334756.6 discloses a method for shaping and combining polishing of sapphire aspherical elements based on temperature-controlled magnetorheology. This patent employs a combination of CCOS immersion polishing, magnetorheological polishing, and ion beam polishing to process sapphire aspherical elements. This combined processing method involves multiple techniques and requires switching between various methods and equipment based on surface defects, resulting in low efficiency. Furthermore, the magnetorheological polishing and ion beam polishing equipment are expensive and costly.

[0005] Chinese patent CN202310117169.4 discloses an integrated processing equipment for grinding, polishing, and inspection of small-diameter aspherical optical elements. This patent integrates grinding, polishing, and inspection mechanisms, enabling integrated processing and inspection of aspherical optical elements. However, it requires changing polishing heads of different sizes during processing, and the methods used are all traditional contact processing. Even in the final fine polishing process, damage and defects are easily left on the workpiece surface, and it is difficult to guarantee the surface accuracy of the aspherical optical elements.

[0006] Chinese patent CN202310027479.7 discloses a shear-thickening polishing device and method for optical lenses. This patent utilizes the shear-thickening effect of non-Newtonian fluids to design a contouring tool for non-contact polishing of optical lenses, thereby obtaining optical lenses with high surface quality. However, this device and method can only perform polishing and is difficult to use for reshaping aspherical lenses. Summary of the Invention

[0007] In view of the problems of high equipment cost, complicated processing steps and low efficiency in the current processing of optical aspherical lenses, this invention proposes an integrated processing device and method for repairing and polishing optical aspherical lenses that is low in cost, simple in processing steps and highly efficient.

[0008] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0009] An integrated processing device for repairing and polishing aspherical lenses includes a contouring tool, a liquid supply pump, a polishing liquid tank, an adsorption fixture, a rotary platform, a rotary motor, and a three-axis motion platform.

[0010] The three-axis motion platform includes a platform, an X-axis track, an X-axis slider, a truss, a Y-axis track, a Y-axis slider, a Z-axis track, and a Z-axis slider. The X-axis track is fixed to the platform, and the X-axis slider is slidably connected to the X-axis track. The Y-axis track is fixed to the crossbeam of the truss, and the Y-axis slider is slidably connected to the Y-axis track. The Z-axis track is fixed to the Y-axis slider, and the Z-axis slider is slidably connected to the Z-axis track. The X-axis slider, Y-axis slider, and Z-axis slider are controlled by corresponding ball screw structures to control their movement speed and distance.

[0011] The rotary motor is fixed on the Z-axis slider;

[0012] The contouring tool is coaxially mounted on a rotary motor and moves with the rotary motor;

[0013] The polishing liquid tank is fixed on the X-axis slider of the three-axis motion platform;

[0014] The rotating platform is fixed at the center of the polishing liquid tank, and the adsorption clamp is fixed on the rotating platform;

[0015] The liquid supply pump is installed above the polishing liquid tank and delivers coolant.

[0016] Furthermore, the contouring tool is a full-diameter aspherical contour contouring polishing head made of nickel-phosphorus alloy, with 0.5-0.7mm sandpaper or damping polishing pads adhered to its surface.

[0017] Furthermore, the rotation axis of the full-diameter aspherical contour polishing head is set to horizontal.

[0018] Furthermore, the polishing liquid tank has an outlet at the bottom, through which coolant is discharged.

[0019] Furthermore, the contouring tool includes a contouring tool for convex aspherical lenses and a contouring tool for concave aspherical lenses.

[0020] Furthermore, the coolant is a liquid medium used to cool the workpiece.

[0021] A method for integrated aspherical lens repair and polishing, utilizing an integrated aspherical lens repair and polishing device, includes the following steps:

[0022] Step 1: Based on the contour curve of the target aspherical lens, design the corresponding contouring tool in 3D software and create a model.

[0023] Step 2: Create the contour machining tool. Import the model into the programming software of the CNC single-point diamond turning machine, write the program for the tool movement trajectory, and turn the nickel-phosphorus alloy bar according to the program to obtain a high-precision contour machining tool.

[0024] Step 3: Perform contact-type shaping. Use hot melt adhesive to fix the suction fixture to the rotating platform. Then, fix the spherical lens closest to the target aspherical lens to the center of the polishing liquid tank using the suction fixture. During the fixing process, use a dial indicator to ensure that the concentricity error between the spherical lens and the rotating platform is within ±10μm. Attach sandpaper to the surface of the contouring tool and install it on the rotary motor. Adjust the Z-axis slider to make the surface of the contouring tool contact the surface of the spherical lens. Turn on the liquid supply pump and adjust the coolant flow rate to 200-250ml / min. Adjust the rotation speed of the rotating platform to 5-6r / min and the rotation speed of the rotary motor to 800-1000rpm. Move the Z-axis slider towards the lens at a speed of 0.5mm / min, with the maximum movement distance being the maximum deviation between the contours of the spherical and aspherical lenses.

[0025] Step 4: Inspect the surface profile. After reshaping, measure the surface profile of the aspherical lens. If the profile error of the aspherical lens after reshaping is less than 10μm, proceed to step 5; otherwise, return to step 3 and replace the sandpaper.

[0026] Step 5: Perform non-contact polishing. Close the outlet at the bottom of the polishing liquid tank, remove the liquid supply pump, replace the sandpaper on the surface of the contouring tool with a damping polishing pad, adjust the Z-axis slider of the three-axis motion platform to make the gap between the surface of the contouring tool and the surface of the aspherical lens 0.1-0.2mm, pour the shear-thickening polishing liquid into the liquid supply tank until the aspherical lens is completely submerged, adjust the rotation speed of the rotary platform to 4-5r / min, and adjust the rotation speed of the rotary motor to 1200-3000rpm to perform non-contact polishing on the aspherical lens.

[0027] Step 6: Inspect surface quality and contour error. Inspect the surface quality and contour of the aspherical lens after polishing. If the contour error of the aspherical lens is less than 1μm and the surface roughness is less than 10nm, then polishing is complete; otherwise, return to step 5.

[0028] Furthermore, the grit size of the sandpaper mentioned in the third step is: 800# for the first time, 1200# for the second time, 2500# for the third time, 3000# for the fourth time, and 3000# for the third time and thereafter.

[0029] Furthermore, the shear-thickening polishing fluid described in step five is a mixture of deionized water, polyhydroxy polymer particles, abrasive particles, and an oxidant. The polyhydroxy polymer particles comprise 25-35 wt.% of the mixture; the abrasive particles are selected from one or more combinations of alumina, silicon carbide, diamond, cerium oxide, and zirconium oxide, with a particle size of 0.05-5 μm and a proportion of 5-15 wt.%; the oxidant is selected from either hydrogen peroxide or potassium permanganate.

[0030] The beneficial effects of this invention are as follows:

[0031] 1. This invention designs a corresponding contouring tool based on the surface contour curve of the target aspherical lens. First, the material is quickly removed through contact processing to obtain a surface contour close to that of the aspherical lens. Then, the contouring tool is used to perform non-contact polishing on the modified aspherical lens using a shearing thickening polishing method to obtain a high-quality aspherical lens with high surface accuracy. At the same time, since there is no need to change the processing tools and equipment, the processing efficiency can be greatly improved.

[0032] 2. The contouring tool designed in this invention achieves better surface accuracy of the aspherical lens with a high material removal rate during the shaping stage. In the polishing stage, a non-contact method is adopted, which on the one hand avoids introducing defects and damage, and on the other hand can adaptively achieve high surface accuracy and surface quality, ultimately realizing the processing of aspherical lenses with high surface accuracy and low surface roughness. Attached Figure Description

[0033] Figure 1 A schematic diagram of the contouring and reshaping process for an outwardly convex spherical lens;

[0034] Figure 2 for Figure 1 Top view;

[0035] Figure 3 This is a schematic diagram of a reshaped convex aspherical lens.

[0036] Figure 4 This is a schematic diagram of the contour polishing process for a convex aspherical lens after reshaping.

[0037] Figure 5 A schematic diagram of the contouring and shaping process for a concave spherical lens;

[0038] Figure 6 This is a schematic diagram of a concave aspherical lens after reshaping.

[0039] Figure 7 This is a schematic diagram of the contour polishing process for a concave aspherical lens after reshaping.

[0040] Figure 8 A schematic diagram of the process for refinishing a spherical lens into an aspherical lens.

[0041] In the diagram: 1- Convex aspherical lens contouring tool; 2- Liquid supply pump; 3- Coolant; 4- Polishing fluid tank; 5- Convex spherical lens; 6- Adsorption fixture; 7- Rotary platform; 8- Rotary motor; 9- Three-axis motion platform; 10- Convex aspherical lens after shaping; 11- Shear-thickening polishing fluid; 12- Concave aspherical lens contouring tool; 13- Concave spherical lens; 14- Concave aspherical lens after shaping. Detailed Implementation

[0042] The principles and technical solutions of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the following implementations, other embodiments obtained by those skilled in the art without creative effort are all within the scope of protection of the present invention.

[0043] Example 1: Shaping and polishing of a 100mm diameter convex aspherical lens.

[0044] like Figure 1-4 As shown, the steps for reshaping and polishing a 100mm diameter convex spherical lens into an aspherical lens are as follows:

[0045] Step 1: Based on the surface contour of the target convex aspherical lens 10, a contouring tool 1 for the convex aspherical lens is machined using a single-point diamond turning process. 800# sandpaper is then applied to the surface of the contouring tool 1, and it is fixed to the rotary motor 8 via a coupling. The polishing fluid tank 4 is bolted to the X-axis slider of the three-axis motion platform 9. The rotary platform 7 is then bolted to the center of the polishing fluid tank 4. A 100mm convex spherical lens 5 is fixed to the rotary platform 7 using a suction clamp 6, ensuring the concentricity of the convex spherical lens 5 and the rotary platform 7. The X, Y, and Z-axis sliders of the three-axis motion platform 9 are adjusted to align the rotation center of the contouring tool 1 with the center of the convex spherical lens 5, bringing the contouring tool 1 into contact with the surface of the convex spherical lens 5.

[0046] Step 2: Open the outlet switch at the lower right corner of the polishing liquid tank 4. Set the flow rate of the liquid supply pump 2 to 200-250 ml / min, the rotation speed of the rotating platform 7 to 5-6 r / min, and the rotation speed of the rotating motor 8 to 800-1000 rpm. The speed of the rotating motor 8 moving in the negative Z-direction of the track should be 0.5 mm / min, and the maximum movement distance should be the maximum difference between the contours of the convex spherical lens 5 and the modified convex aspherical lens 10. Start the liquid supply pump 2, rotating platform 7, and rotating motor 8 in sequence.

[0047] Step 3: After the Z-axis slider of the three-axis motion platform 9 moves to the lowest point and returns to the initial point, replace the 800# sandpaper on the surface of the contouring tool 1 with 1200# sandpaper (replace with 2500# and 3000# sandpaper in sequence when returning later). After processing, measure the surface contour of the convex aspherical lens 10 after shaping. If the maximum error of the surface contour is less than 10μm, proceed to the next step. Otherwise, attach 3000# sandpaper to the contouring tool 1 and continue contact processing until the measurement is qualified.

[0048] Step 4: Close the outlet of the polishing slurry tank 4, remove the slurry supply pump 2, and replace the sandpaper on the surface of the contouring tool 1 with a damping pad. Set the rotation speed of the rotary platform 7 to 4-5 r / min and the rotation speed of the rotary motor 8 to 1200-3000 rpm. Adjust the Z-axis slider of the three-axis motion platform 9 to make the polishing gap between the contouring tool 1 and the modified convex aspherical lens 10 0.01-0.02 mm. Prepare the shear-thickening polishing slurry 11 and pour it into the polishing slurry tank 4 until it submerges the highest point of the modified convex aspherical lens 10. Start the rotary platform 7 and the rotary motor 8 in sequence to perform non-contact polishing. The material removal rate of the non-contact polishing method is mainly related to the polishing gap. Therefore, in non-contact polishing, the contour error caused by the unevenness left after contact polishing results in a higher material removal rate for the raised parts due to the smaller gap with the surface of the processing tool, while the material removal rate for the pits is slower due to the larger gap with the surface of the processing tool. Ultimately, this adaptively achieves high surface accuracy and high surface quality aspherical lens polishing.

[0049] Step 5: After polishing for 30 minutes, check the surface shape accuracy and surface roughness of the convex aspherical lens 10 after shaping. If the surface shape error is less than 1μm and the surface roughness is less than 10nm, then polishing is complete. Otherwise, return to step 4 and perform non-contact polishing again, and check again until it meets the processing requirements.

[0050] Step 6: Done.

[0051] Example 2: Shaping and polishing of a 100mm diameter concave aspherical lens.

[0052] like Figure 5-7 As shown, a 100mm diameter concave spherical lens is reshaped and polished into an aspherical lens. This embodiment differs from Example 1 in that the workpiece being processed is a concave spherical lens 13, and the corresponding contouring tool used is a concave aspherical lens contouring tool 12. Other steps and parameter settings are the same as in Example 1.

[0053] The above-described embodiments are merely illustrative of the implementation methods of the present invention, but should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the protection scope of the present invention.

Claims

1. A method for integrated repair and polishing of aspherical lenses, characterized in that: The aspherical lens is processed using an integrated processing device for repair and polishing. The device includes a contouring tool, a liquid supply pump (2), a polishing liquid tank (4), an adsorption fixture (6), a rotating platform (7), a rotating motor (8), and a three-axis motion platform (9). The aforementioned contouring tool is a full-diameter aspherical contour contouring polishing head, made of nickel-phosphorus alloy, with 0.5-0.7 mm sandpaper or damping polishing pads adhered to its surface; The method includes the following steps: Step 1: Based on the contour curve of the target aspherical lens, design the corresponding contouring tool in 3D software and create a model; Step 2: Create a contouring tool; import the model into the programming software of the CNC single-point diamond turning machine tool, write the program for the tool movement trajectory, and turn the nickel-phosphorus alloy bar according to the program to obtain a high-precision contouring tool. Step 3: Perform contact shaping; use hot melt adhesive to fix the adsorption fixture (6) on the rotating platform (7), and then fix the spherical lens closest to the target aspherical lens in the center of the polishing liquid tank (4) through the adsorption fixture (6). During the fixing process, use a dial indicator to ensure that the concentricity error between the spherical lens and the rotating platform (7) is within ±10 µm; attach sandpaper to the surface of the contouring tool and install it on the rotary motor (8), adjust the Z-axis slider to make the surface of the contouring tool contact the surface of the spherical lens, turn on the liquid supply pump (2) and adjust the flow rate of the coolant (3) to 200-250 ml / min, adjust the rotation speed of the rotating platform (7) to 5-6 r / min, adjust the rotation speed of the rotary motor (8) to 800-1000 rpm, and move the Z-axis slider towards the spherical lens at a speed of 0.5 mm / min. The maximum moving distance is the maximum distance of the contour deviation between the spherical lens and the aspherical lens. Step 4: Inspect the surface profile; After reshaping, measure the surface profile of the aspherical lens. If the profile error of the aspherical lens after reshaping is less than 10 μm, proceed to step 5; otherwise, return to step 3 and replace the sandpaper. Step 5: Perform non-contact polishing; close the outlet at the bottom of the polishing liquid tank (4), remove the liquid supply pump (2), replace the sandpaper on the surface of the contouring tool with a damping polishing pad, adjust the Z-axis slider of the three-axis motion platform (9) to make the gap between the surface of the contouring tool and the surface of the aspherical lens 0.1-0.2 mm, pour the shear thickening polishing liquid (11) into the polishing liquid tank (4) until the aspherical lens is completely submerged, adjust the rotation speed of the rotating platform (7) to 4-5 r / min, adjust the rotation speed of the rotary motor (8) to 1200-3000 rpm, and perform non-contact polishing on the aspherical lens; Step 6: Inspect surface quality and contour error; Inspect the surface quality and contour of the aspherical lens after polishing. If the contour error of the aspherical lens is less than 1 μm and the surface roughness is less than 10 nm, then polishing is complete; otherwise, return to step 5.

2. The integrated processing method for repairing and polishing aspherical lenses according to claim 1, characterized in that: The grit size of the sandpaper used in the third step is as follows: 800# for the first time, 1200# for the second time, 2500# for the third time, 3000# for the fourth time, and 3000# for the second time.

3. The integrated processing method for repairing and polishing aspherical lenses according to claim 1, characterized in that: The shear-thickening polishing fluid (11) mentioned in step 5 is a mixture of deionized water, polyhydroxy polymer particles, abrasive particles, and oxidant; the polyhydroxy polymer particles are in a proportion of 25-35 wt.%; the abrasive particles are selected from one or more of alumina, silicon carbide, diamond, cerium oxide, and zirconium oxide, with a particle size of 0.05-5 μm and a proportion of 5-15 wt.%; the oxidant is selected from hydrogen peroxide and potassium permanganate.

4. The integrated processing method for repairing and polishing aspherical lenses according to claim 1, characterized in that: The three-axis motion platform (9) includes a table, an X-axis rail, an X-axis slider, a truss, a Y-axis rail, a Y-axis slider, a Z-axis rail, and a Z-axis slider. The X-axis rail is fixed on the table, and the X-axis slider is slidably connected to the X-axis rail. The Y-axis rail is fixed on the crossbeam of the truss, and the Y-axis slider is slidably connected to the Y-axis rail. The Z-axis rail is fixed on the Y-axis slider, and the Z-axis slider is slidably connected to the Z-axis rail. The X-axis slider, Y-axis slider, and Z-axis slider are controlled by corresponding ball screw structures to control their movement speed and distance. The rotary motor (8) is fixed on the Z-axis slider; The contouring tool is coaxially mounted on the rotary motor (8) and moves with the rotary motor (8); The polishing liquid tank (4) is fixed on the X-axis slider of the three-axis motion platform (9); The rotating platform (7) is fixed at the center of the polishing liquid tank (4), and the adsorption clamp (6) is fixed on the rotating platform (7); The liquid supply pump (2) is installed above the polishing liquid tank (4) and delivers coolant (3).

5. The integrated processing method for repairing and polishing aspherical lenses according to claim 1, characterized in that: The rotation axis of the full-diameter aspherical contour polishing head is set to horizontal.

6. The integrated processing method for repairing and polishing aspherical lenses according to claim 1, characterized in that: The polishing liquid tank (4) has an outlet at the bottom, through which the coolant (3) is discharged.

7. The integrated processing method for repairing and polishing aspherical lenses according to claim 1, characterized in that: The contouring tools include a contouring tool (1) for convex aspherical lenses and a contouring tool (12) for concave aspherical lenses.

8. The integrated processing method for repairing and polishing aspherical lenses according to claim 1, characterized in that: The coolant (3) is a liquid medium used to cool the workpiece.

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