CN117733661A - High polishing method and high polishing equipment for ultra-smooth surface of optical element - Google Patents
High polishing method and high polishing equipment for ultra-smooth surface of optical element Download PDFInfo
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- CN117733661A CN117733661A CN202311873137.3A CN202311873137A CN117733661A CN 117733661 A CN117733661 A CN 117733661A CN 202311873137 A CN202311873137 A CN 202311873137A CN 117733661 A CN117733661 A CN 117733661A
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- 238000005498 polishing Methods 0.000 title claims abstract description 414
- 230000003287 optical effect Effects 0.000 title claims abstract description 55
- 238000000034 method Methods 0.000 title claims abstract description 49
- 239000007788 liquid Substances 0.000 claims abstract description 61
- 238000012545 processing Methods 0.000 claims abstract description 25
- 230000003746 surface roughness Effects 0.000 claims abstract description 22
- 229920002635 polyurethane Polymers 0.000 claims abstract description 14
- 239000004814 polyurethane Substances 0.000 claims abstract description 14
- 238000005507 spraying Methods 0.000 claims abstract description 13
- 239000000243 solution Substances 0.000 claims description 28
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 22
- 239000000741 silica gel Substances 0.000 claims description 20
- 229910002027 silica gel Inorganic materials 0.000 claims description 20
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims description 18
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 18
- 239000010985 leather Substances 0.000 claims description 17
- 238000000227 grinding Methods 0.000 claims description 14
- 238000001514 detection method Methods 0.000 claims description 11
- 239000000843 powder Substances 0.000 claims description 7
- 230000001678 irradiating effect Effects 0.000 claims description 6
- 235000006408 oxalic acid Nutrition 0.000 claims description 6
- 239000008188 pellet Substances 0.000 claims description 6
- 238000002360 preparation method Methods 0.000 claims description 6
- 239000008213 purified water Substances 0.000 claims description 6
- 238000001228 spectrum Methods 0.000 claims description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 6
- 239000011259 mixed solution Substances 0.000 claims description 5
- 238000004458 analytical method Methods 0.000 claims description 3
- 230000005540 biological transmission Effects 0.000 claims description 3
- 229910052751 metal Inorganic materials 0.000 claims description 3
- 239000002184 metal Substances 0.000 claims description 3
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- 238000005422 blasting Methods 0.000 claims 2
- 238000004519 manufacturing process Methods 0.000 abstract description 9
- 230000000694 effects Effects 0.000 abstract description 7
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- 239000000463 material Substances 0.000 description 9
- 230000008569 process Effects 0.000 description 8
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- 239000002245 particle Substances 0.000 description 5
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 3
- 238000007517 polishing process Methods 0.000 description 3
- 229910000420 cerium oxide Inorganic materials 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical group [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 description 2
- 239000004970 Chain extender Substances 0.000 description 1
- 229920001730 Moisture cure polyurethane Polymers 0.000 description 1
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- 230000007123 defense Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005187 foaming Methods 0.000 description 1
- 239000004088 foaming agent Substances 0.000 description 1
- 239000005350 fused silica glass Substances 0.000 description 1
- 238000010884 ion-beam technique Methods 0.000 description 1
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- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical group [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 description 1
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- Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
Abstract
The invention discloses a high polishing method for an ultra-smooth surface of an optical element, which belongs to the technical field of optical element polishing and comprises the following steps: firstly, selecting a polishing mold which is matched with the shape of the surface to be processed of a workpiece according to the type of the workpiece; then, the rough polishing liquid is sprayed onto a first polishing skin made of polyurethane, so that the rough polishing liquid flows between a workpiece and the first polishing skin, and the polishing of the surface accuracy delta N of the workpiece is less than or equal to 0.3fr; and then spraying the fine polishing liquid onto a second polishing skin made of polyurethane, so that the fine polishing liquid flows between the workpiece and the second polishing skin, and finally, the polishing with the surface roughness RMS of the workpiece being less than or equal to 0.5nm is realized. The polishing device can achieve the same ultra-smooth surface effect on various high polishing devices, is wide in application range, large in processing area and high in polishing efficiency, and is simple to operate and low in production cost and labor cost.
Description
Technical Field
The invention relates to the technical field of optical element polishing, in particular to a high polishing method for an ultra-smooth surface of an optical element and high polishing equipment implemented by adopting the high polishing method for the ultra-smooth surface of the optical element.
Background
In recent years, the optical element is increasingly widely applied in the fields of aerospace, national defense and military industry, nuclear energy industry, astronomical detection, photoelectric industry and the like, particularly the optical element applied in short-wave ultraviolet light and strong laser has high requirements on the surface shape and roughness of the optical element, for example, the roughness index is developed from tens of nanometers to less than 1 nanometer of the traditional optical element, namely the ultra-smooth surface processing of the optical element.
The existing ultra-smooth surface processing technology of the optical element mainly adopts the following methods: bath polishing, ultra-precise air bag polishing, magnetorheological polishing, ion beam polishing, abrasive jet polishing and other technologies have all obtained the smooth surface of the optical element with sub-nanometer precision, but all have certain limitations.
In the float polishing technology, the grinding disc is made of more than 99.99% of metallic tin, and fine spiral lines are turned on the surface of the grinding disc to perform softening treatment. During operation, the polishing liquid submerges the polishing disc and the processing surface of the workpiece, the tin coil main shaft rotates, the workpiece coils and floats on the tin disc to do self-fixed rotation, the dynamic pressure generated by the motion of the polishing liquid enables a liquid film with the thickness of a plurality of micrometers to exist between the workpiece and the millstone, and fine polishing particles move in the liquid film and collide with the surface of the workpiece continuously so as to remove materials. The method can process the ultra-smooth surface with the roughness RMS within 0.5nm and the surface type precision is higher than lambda/20, but the method is only suitable for polishing a planar workpiece, and the uniformity of polishing solution is kept continuously in the processing process, so that the requirements on the technological process are very strict.
The abrasive jet polishing technology is realized by utilizing jet liquid beams mixed with abrasive to impact the surface of an optical part, wherein the jet is in contact with a workpiece in a point or small area in the polishing process, the processing area is small, and the polishing efficiency is low.
Disclosure of Invention
In order to overcome the defects of the prior art, one of the purposes of the invention is to provide a high polishing method for an ultra-smooth surface of an optical element, which has the advantages of wider application range, larger processing area and higher polishing efficiency.
In order to overcome the defects of the prior art, the second aim of the invention is to provide high polishing equipment with wider application range, larger processing area and higher polishing efficiency.
One of the purposes of the invention is realized by adopting the following technical scheme:
a method of high polishing an ultra-smooth surface of an optical element, comprising the steps of:
rough polishing is carried out on the workpiece:
setting the rotating speed of a main shaft of high-polishing equipment;
according to the type of the workpiece, selecting a polishing mold which is matched with the shape of the surface to be processed of the workpiece, and then installing a first polishing leather made of polyurethane on the polishing mold connected with the main shaft;
placing a clamp holding a workpiece on a polishing mold so that a polishing surface of the workpiece is in contact with a first polishing leather surface;
putting down a swing shaft of the high-throwing equipment to enable the swing shaft to be in contact with the clamp;
starting high polishing equipment, driving a polishing mold and a first polishing skin to rotate by a main shaft, simultaneously running a swinging shaft and the main shaft, pressurizing a clamp by a pneumatic system, transferring the clamp to a workpiece, spraying rough polishing liquid onto the first polishing skin by a nozzle, enabling the rough polishing liquid to flow between the workpiece and the first polishing skin, and polishing the surface accuracy delta N of the workpiece is less than or equal to 0.3fr;
carrying out fine polishing on a workpiece:
setting the rotating speed of a main shaft of high-polishing equipment;
a second polishing leather made of polyurethane is arranged on a polishing mould connected with the main shaft;
placing a clamp holding the workpiece subjected to rough polishing on a polishing mold so that a polishing surface of the workpiece is in contact with a second polishing leather surface;
putting down a swing shaft of the high-throwing equipment to enable the swing shaft to be in contact with the clamp;
starting high polishing equipment, driving the polishing mold and the second polishing skin to rotate by the main shaft, simultaneously running the swinging shaft and the main shaft, pressurizing the clamp through the pneumatic system, transferring the clamp to the workpiece, spraying the fine polishing liquid onto the second polishing skin through the nozzle, enabling the fine polishing liquid to flow between the workpiece and the second polishing skin, and finally realizing polishing with the surface roughness RMS of the workpiece being less than or equal to 0.5 nm.
Further, in the rough polishing step of the workpiece, the model of the first polishing skin is LP66; the preparation method of the rough polishing liquid comprises the following steps: preparing 2815 polishing powder and purified water according to the specific weight of 1.005-1.01, and gradually adding oxalic acid or sodium hydroxide until the pH value of the prepared mixed solution reaches 6-8.
Further, in the step of performing finish polishing on the workpiece, the model of the second polishing skin is LP57 or LASER; the preparation method of the fine polishing liquid comprises the following steps: gradually adding the silica gel solution P-80 or the silica gel solution P-50 and purified water according to the volume of 1: 1.5-2, and gradually adding oxalic acid liquid or sodium hydroxide liquid until the pH value of the prepared mixed solution reaches 7-9.
Further, the method for highly polishing the ultra-smooth surface of the optical element further comprises a step of obtaining an initial surface morphology of the workpiece, wherein the step of obtaining the initial surface morphology of the workpiece is located before the step of rough polishing the workpiece, and specifically comprises the following steps: and placing the unpolished workpiece on an objective table, and acquiring the initial surface morphology of the unpolished workpiece by an image acquisition device for comparison analysis with the surface morphology of the workpiece after rough polishing.
Further, the method for highly polishing the ultra-smooth surface of the optical element further comprises a surface morphology detection step, wherein the surface morphology detection step is positioned between the step of rough polishing the workpiece and the step of finish polishing the workpiece, and specifically comprises the following steps:
placing the coarsely polished sample to be tested on an objective table, adjusting a light path to enable the sample to be tested and a standard reflector to be positioned at a zero optical path difference position, and scanning the sample to be tested according to a preset scanning path;
the method comprises the steps of obtaining sample light returned by a first light source irradiating a sample to be detected and standard light returned by a second light source irradiating a standard reflector to interfere with each other, and generating sample interference fringes;
sampling the sample interference fringes by utilizing a spectrometer to generate a sample interference spectrum;
performing image processing on the sample interference spectrum to obtain the current surface morphology of the sample to be detected;
and comparing the current surface morphology with the initial surface morphology to obtain the polishing degree of the workpiece to be tested.
Further, the high polishing method for the ultra-smooth surface of the optical element further comprises a step of performing high-speed fine polishing on the workpiece, wherein the step of performing high-speed fine polishing on the workpiece is positioned before the step of performing rough polishing on the workpiece, and specifically comprises the following steps of:
determining processing parameters, metal pellets and resin pellets of high-speed fine grinding equipment according to the finished product polishing requirements of the workpiece;
and controlling the low surface shape precision of the workpiece after high-speed finish grinding to be smaller than or equal to a preset value according to the finish grinding processing parameters, and simultaneously controlling the external dimension and the surface roughness of the workpiece to meet the finished product polishing requirement.
Further, in the step of performing rough polishing on the workpiece, the polishing removal amount is more than or equal to 0.02nm;
in the step of carrying out finish polishing on the workpiece, the polishing removal amount is more than or equal to 0.002nm, and the surface precision delta N is less than or equal to 0.3fr.
The second purpose of the invention is realized by adopting the following technical scheme:
the high polishing equipment for the ultra-smooth surface of the optical element is implemented by adopting the high polishing method for the ultra-smooth surface of any one of the optical elements, and comprises a main shaft, a polishing die, a swinging shaft, a clamp, a first polishing skin, a second polishing skin, a nozzle and a pneumatic system, wherein the main shaft is in transmission connection with the polishing die, the polishing die is matched with the surface of a workpiece in shape, the first polishing skin and the second polishing skin are made of polyurethane and are fixedly connected with the polishing die, the clamp clamps the workpiece, the swinging shaft is positioned above the clamp and the workpiece, the pneumatic system is used for pressurizing the clamp and the workpiece so that the workpiece is in surface contact with the first polishing skin and the second polishing skin, and the nozzle is used for spraying rough polishing liquid onto the first polishing skin so that the rough polishing liquid flows between the workpiece and the first polishing skin, and the surface precision delta N of the workpiece is less than or equal to 0.3; the nozzle is used for spraying the fine polishing liquid onto the second polishing skin, so that the fine polishing liquid flows between the workpiece and the second polishing skin, and finally polishing with the surface roughness RMS of the workpiece being less than or equal to 0.5nm is realized.
Further, the first polishing skin and the second polishing skin are both detachably arranged on the polishing mold.
Further, the number of the polishing dies is two, the first polishing leather is adhered to one polishing die, and the second polishing leather is adhered to the other polishing die.
Compared with the prior art, the high polishing method for the ultra-smooth surface of the optical element comprises the following steps of: firstly, selecting a polishing mold which is matched with the shape of the surface to be processed of a workpiece according to the type of the workpiece; then, the rough polishing liquid is sprayed onto a first polishing skin made of polyurethane, so that the rough polishing liquid flows between a workpiece and the first polishing skin, and the polishing of the surface accuracy delta N of the workpiece is less than or equal to 0.3fr; and then spraying the fine polishing liquid onto a second polishing skin made of polyurethane, so that the fine polishing liquid flows between the workpiece and the second polishing skin, and finally, the polishing with the surface roughness RMS of the workpiece being less than or equal to 0.5nm is realized. The method can achieve the same ultra-smooth surface effect on various high-polishing equipment, has the advantages of wide application range, large processing area and high polishing efficiency, and is simple to operate, low in production cost and labor cost; when the second polishing skin with the model of LP57 and the silica gel solution P-80 are adopted for matching, or the second polishing skin with the model of LASER and the silica gel solution P-80 are adopted for matching, the two processes can meet the requirement that the surface roughness is less than or equal to 0.5nm, the surface texture problem of the workpiece is not easy to occur, the workpiece is not damaged, and the polishing quality of the workpiece is ensured.
Drawings
FIG. 1 is a flow chart of the steps of the method for high polishing an ultra-smooth surface of an optical element according to the present invention;
FIG. 2 is a detailed step flow diagram of the method of high polishing the ultra-smooth surface of the optical element of FIG. 1;
FIG. 3 is a flow chart of a surface morphology detection step of the high polishing method of the ultra-smooth surface of the optical element of FIG. 2;
FIG. 4-a is a schematic illustration of the effect of the abrasive jet polishing technique of the background art;
FIG. 4-b is a schematic illustration of the effect of a high-polishing method employing an ultra-smooth surface of an optical element according to the present invention;
fig. 5 is a schematic structural view of the ultra-smooth surface high polishing apparatus of the optical element of the present invention.
In the figure: 10. a main shaft; 20. polishing the mold; 30. a swing shaft; 40. a clamp; 50. and (3) a nozzle.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It will be understood that when an element is referred to as being "fixed to" another element, it can be directly on the other element or be present as another intermediate element through which the element is fixed. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. When an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like are used herein for illustrative purposes only.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
As shown in fig. 1, the method for highly polishing the ultra-smooth surface of the optical element comprises the following steps:
rough polishing is carried out on the workpiece:
setting the rotating speed of a main shaft 10 of high-polishing equipment;
according to the type of the workpiece, selecting a polishing mold 20 which is matched with the shape of the surface to be processed of the workpiece, and then installing a first polishing skin made of polyurethane on the polishing mold 20 connected with the main shaft 10;
placing the jig 40 holding the workpiece on the polishing mold 20 so that the polished surface of the workpiece is in contact with the first polishing leather surface;
the swing shaft 30 of the high-throwing device is put down to be abutted against the clamp 40;
starting high polishing equipment, wherein the main shaft 10 drives the polishing mould 20 and the first polishing skin to rotate, the swinging shaft 30 and the main shaft 10 operate simultaneously, the clamp 40 is pressurized by a pneumatic system and is transferred to a workpiece, and the rough polishing liquid is sprayed onto the first polishing skin by the nozzle 50, so that the rough polishing liquid flows between the workpiece and the first polishing skin, and the polishing of the surface accuracy delta N of the workpiece is less than or equal to 0.3fr;
carrying out fine polishing on a workpiece:
setting the rotating speed of a main shaft 10 of high-polishing equipment;
a second polishing skin made of polyurethane is arranged on a polishing mould 20 connected with a main shaft 10;
placing a jig 40 holding the workpiece having undergone rough polishing onto the polishing mold 20 so that the polished surface of the workpiece is in contact with the second polishing skin surface;
the swing shaft 30 of the high-throwing device is put down to be abutted against the clamp 40;
starting high polishing equipment, driving the polishing mold 20 and the second polishing skin to rotate by the main shaft 10, simultaneously running the swing shaft 30 and the main shaft 10, pressurizing the clamp 40 by a pneumatic system, transferring the clamp to a workpiece, spraying the fine polishing liquid onto the second polishing skin by the nozzle 50, enabling the fine polishing liquid to flow between the workpiece and the second polishing skin, and finally realizing polishing with the surface roughness RMS of the workpiece being less than or equal to 0.5 nm.
In the rough polishing step of the workpiece, the rotation speed of the main shaft 10 of the high polishing device is set to 2000-2500r/min. Other processing parameters of the high-polishing device, such as angle, swing, pressure, time, etc., can be set according to actual production requirements, and are not described herein.
The existing optical element is mainly divided into two major types of planar workpieces and spherical workpieces, the adaptive polishing die 20 can be selected for use according to the type of the workpiece to be processed, the inner diameter of the polishing die 20 is larger than the outer diameter of the workpiece surface, the polishing surface of the workpiece is in surface contact with the polishing skin, and the contact area is large.
In this embodiment, a concave mirror with a material of N-SF11, model R124.266, and diameter of 21.2mm was used for rough polishing test, and the use parameters and test results are shown in table 1:
TABLE 1
Wherein, the material of first polishing skin is polyurethane, is made by a special micropore foaming material, and the manufacturing method specifically comprises: the polyurethane prepolymer, the hardener (chain extender) and the foaming agent are mixed according to the prescribed amount, then are injected into a shaping container to be made into a block shape, and then are processed into a final sheet-shaped polished skin by a slicing machine, and the polished skin can be very hard and maintain porous at the same time, so that high-level flatness, such as polishing of optical lenses, is processed. In addition, it can be concluded that: the first polishing leather with the model of LP57 (no filling abrasive) or LP66 (the filling abrasive is cerium oxide) is adopted to carry out rough polishing by matching with rough polishing liquid, the surface roughness RMS and the surface type precision delta N of a workpiece are not greatly different, and the roughness RMS and the surface type precision delta N of the processing of LP26 (the filling abrasive is zirconium oxide) are obviously higher than those of LP57 and LP66, so that the rough polishing effect of the first polishing leather of LP26 is poor; in addition, because the polishing finish of the LP57 processing is poor, when the workpiece is roughly polished, a first polishing skin with the model of LP66 and a rough polishing liquid containing 2815 powder are selected, and the specific preparation method of the rough polishing liquid is as follows: preparing 2815 polishing powder and purified water according to the specific weight of 1.005-1.01, and gradually adding oxalic acid or sodium hydroxide until the pH value of the prepared mixed solution reaches 6-8. Finally, the polishing of the surface type precision delta N of the workpiece is not more than 0.3fr, and the polishing removal amount is not less than 0.02nm.
In the step of carrying out finish polishing on the workpiece, the rotating speed of the main shaft 10 of the high polishing equipment is set to be 1000-2000r/min. Other processing parameters of the high-polishing device, such as angle, swing, pressure, time, etc., can be set according to actual production requirements, and are not described herein.
In an embodiment, a concave mirror with a material of N-SF11, a model of R124.266, and a diameter of 21.2mm is used for the rough polishing and fine polishing test, wherein the rough polishing test uses a first polishing pad with a model of LP66 and a rough polishing solution containing 2815 powder in combination, and the use parameters and test results of the fine polishing test are shown in table 2:
TABLE 2
Wherein, the material of the second polishing skin is substantially the same as that of the first polishing skin, which is not described herein, and in addition, it can be concluded that: the polishing skin and the polishing liquid are 2 key factors influencing the surface roughness of the workpiece, so that the proper polishing skin and polishing liquid are required to obtain the ideal surface roughness; since the surface roughness is to within 0.5nm, test 4 shows that LP66 may be unsuitable because the size of the particle size of the cerium oxide contained in LP66 cannot be determined; experiment 2 and experiment 5 show that the longer the LP57 is used, the better the roughness of the workpiece is, so when the workpiece is subjected to fine polishing, the second polishing skin with the model of LP57 or LASER and the fine polishing liquid containing the silica gel solution P-50 or the silica gel solution P-80 are selected, and the preparation method of the fine polishing liquid is as follows: gradually adding the silica gel solution P-50 or the silica gel solution P-80 and purified water according to the volume of 1: 1.5-2, and gradually adding oxalic acid liquid or sodium hydroxide liquid until the pH value of the prepared mixed liquid reaches 7-9, wherein the silica gel solution P-80 consists of colloidal silica particles with high purity, the particle diameter is 72nm, the phenomenon of scratch generated by processing elements can be avoided, and the polishing solution is particularly suitable for polishing optical elements and the like, but the silica gel solution P-80 is produced by American company, has high price and higher domestic production and use cost; the silica gel solution P-50 is produced by domestic cloud light company, and has smaller particle diameter compared with the silica gel solution P-80, has the same use effect as the silica gel solution P-80, and has convenient domestic purchase and lower cost. Finally, the polishing with the surface roughness RMS of the workpiece being less than or equal to 0.5nm and the polishing removal amount being more than or equal to 0.002nm is realized.
In another embodiment, a convex mirror with a material of N-SF11, a model of R37.815, and a diameter of 21.2mm is used for the rough polishing and fine polishing test, wherein the rough polishing test uses a first polishing pad with a model of LP66 and a rough polishing solution containing 2815 powder in combination, and the use parameters and test results of the fine polishing test are shown in table 3:
TABLE 3 Table 3
It can be further determined that: the process of matching the second polishing skin with the model LP57 and the silica gel solution P-80 polishing liquid can meet the requirement that the surface roughness is less than or equal to 0.5 nm; in addition, as shown in fig. 4-a, if the abrasive jet polishing technology in the background technology is adopted to realize large-area processing, the processing texture problem is easily caused on the surface of the workpiece in the process of controlling the workpiece to move, and the surface texture of the workpiece subjected to finish polishing by adopting the above two matching modes in the application is checked, as shown in fig. 4-b, the surface of the workpiece has no obvious texture, so that the high polishing method is not easy to cause the surface texture problem, cannot damage the workpiece, ensures the polishing quality of the workpiece, and particularly, can meet the requirements of customers when the customers have high quality requirements on optical elements.
In yet another embodiment, a rough polishing and fine polishing test is performed by using an optical element made of fused quartz, wherein the rough polishing test uses a first polishing pad with a model of LP66 and a rough polishing solution containing 2815 powder in combination, and the parameters and test results of the fine polishing test are shown in table 4:
TABLE 4 Table 4
It can be concluded that: tests 8 and 9 show that the same process is adopted, and the surface roughness of the optical element can be different due to different materials of the optical element to be processed, but no matter what material is adopted, the second polishing skin with the model of LASER and the fine polishing liquid containing the silica gel solution P-80 are matched for use, the surface type precision is higher, and the requirement that the surface roughness is less than or equal to 0.5nm is met.
As shown in fig. 2, the high polishing method for the ultra-smooth surface of the optical element further comprises a step of obtaining the initial surface morphology of the workpiece, a step of performing high-speed fine polishing on the workpiece, and a surface morphology detection step.
The specific step of obtaining the initial surface morphology of the workpiece is located before the step of rough polishing the workpiece, and specifically comprises the following steps: and placing the unpolished workpiece on an objective table, and acquiring the initial surface morphology of the unpolished workpiece by an image acquisition device for comparison analysis with the surface morphology of the workpiece after rough polishing.
The high-speed finish grinding step is positioned between the step of obtaining the initial surface morphology of the workpiece and the step of rough polishing the workpiece, and is mainly completed by high-speed finish grinding equipment, and the advantages of high pressure, high rotating speed, accurate control and the like of the high-speed finish grinding equipment are mainly achieved, so that the workpiece is preliminarily and quickly formed, a damaged layer existing on the workpiece can be removed, and the workpiece is rapidly polished to a mirror surface from a blank state. The method specifically comprises the following steps:
determining processing parameters, metal pellets and resin pellets of high-speed fine grinding equipment according to the finished product polishing requirements of the workpiece;
the low surface shape precision of the workpiece after high-speed finish grinding is controlled to be smaller than or equal to a preset value according to the finish grinding machining parameters, and the external dimension and the surface roughness of the workpiece are controlled to meet the finished product polishing requirement.
Controlling the external dimension of the workpiece to meet the requirement of a finished product, comprising:
if the workpiece is a lens, the curvature radius and the center thickness of the workpiece are controlled within the tolerance range required by the finished product.
The surface morphology detection step is located between the rough polishing step and the finish polishing step of the workpiece, and as shown in fig. 3, the surface morphology detection specifically includes the following steps:
placing the coarsely polished sample to be tested on an objective table, adjusting a light path to enable the sample to be tested and a standard reflector to be positioned at a zero optical path difference position, and scanning the sample to be tested according to a preset scanning path;
the method comprises the steps of obtaining sample light returned by a first light source irradiating a sample to be detected and standard light returned by a second light source irradiating a standard reflector to interfere with each other, and generating sample interference fringes;
sampling the sample interference fringes by utilizing a spectrometer to generate a sample interference spectrum;
performing image processing on the sample interference spectrum to obtain the current surface morphology of the sample to be detected;
and comparing the current surface morphology with the initial surface morphology to obtain the polishing degree of the workpiece to be tested. The polishing degree can be judged by roughness, finish, surface shape size information and the like, if the polishing degree reaches a preset value, finish polishing is carried out, and a second polishing skin with the model of LP57 and a silica gel solution P-80 finish polishing solution are adopted for matching; and if the polishing degree does not reach the preset value, repeating the rough polishing step until the polishing degree reaches the preset value.
In the prior art, as the scattering degree of the polishing solution is higher, the polishing solution adhered to the surface of the optical element is required to be cleaned and then subjected to surface morphology detection, so that the detection efficiency is influenced.
In the application, a polishing mold matched with the shape of the surface to be processed of a workpiece is selected according to the type of the workpiece; then, the rough polishing liquid is sprayed onto the first polishing skin, so that the rough polishing liquid flows between the workpiece and the first polishing skin, and polishing of the surface accuracy delta N of the workpiece is realized, wherein delta N is less than or equal to 0.3fr; then, the fine polishing liquid is sprayed onto the second polishing skin, so that the fine polishing liquid flows between the workpiece and the second polishing skin, and finally, the polishing with the surface roughness RMS less than or equal to 0.5nm of the workpiece is realized, therefore, the high polishing method can achieve the same ultra-smooth surface effect on various high polishing equipment, has wider application range, larger processing area and higher polishing efficiency, and is simple to operate, and lower in production cost and labor cost; when the second polishing skin with the model of LP57 and the silica gel solution P-80 are adopted for matching, or the second polishing skin with the model of LASER and the silica gel solution P-80 are adopted for matching, the two processes can meet the requirement that the surface roughness is less than or equal to 0.5nm, the surface texture problem of the workpiece is not easy to occur, the workpiece is not damaged, and the polishing quality of the workpiece is ensured.
As shown in fig. 4, the application further provides a high polishing device for an ultra-smooth surface of an optical element, which is implemented by adopting the high polishing method for the ultra-smooth surface of any one of the optical elements, and comprises a main shaft 10, a polishing mold 20, a swinging shaft 30, a clamp 40, a first polishing skin, a second polishing skin, a nozzle 50 and a pneumatic system, wherein the main shaft 10 is in transmission connection with the polishing mold 20, the polishing mold 20 is matched with the surface of a workpiece in shape, the first polishing skin and the second polishing skin are both made of polyurethane and are fixedly connected with the polishing mold 20, the clamp 40 clamps the workpiece, the swinging shaft 30 is positioned above the clamp 40, the pneumatic system is used for pressurizing the clamp 40 and the workpiece 70, the nozzle 50 is used for spraying rough polishing liquid onto the first polishing skin, so that the rough polishing liquid flows between the workpiece and the first polishing skin, and the polishing precision delta N of the surface of the workpiece is less than or equal to 0.3fr; the nozzle is used for spraying the fine polishing liquid onto the second polishing skin, so that the fine polishing liquid flows between the workpiece and the second polishing skin, and finally polishing with the surface roughness RMS of the workpiece being less than or equal to 0.5nm is realized.
In an embodiment, the first polishing pad and the second polishing pad are detachably mounted on the polishing mold 20, so that only one high polishing device is needed, and the rough polishing and the fine polishing processes can be realized by replacing the first polishing pad and the second polishing pad.
In another embodiment, the number of polishing dies 20 is two, the first polishing skin is adhered to one polishing die 20, the second polishing skin is adhered to the other polishing die 20, and the rough polishing and the fine polishing processes are realized by replacing the two polishing dies 20, so that the operation is convenient, the efficiency is higher, and the production cost is relatively higher.
Compared with the prior art, the high polishing equipment has the advantages of simpler and more compact structure, less occupied space, improved polishing efficiency and lower production cost.
The foregoing examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that, for those skilled in the art, it is possible to make several modifications and improvements without departing from the concept of the present invention, which are equivalent to the above embodiments according to the essential technology of the present invention, and these are all included in the protection scope of the present invention.
Claims (10)
1. The high polishing method for the ultra-smooth surface of the optical element is characterized by comprising the following steps of:
rough polishing is carried out on the workpiece:
setting the rotating speed of a main shaft of high-polishing equipment;
according to the type of the workpiece, selecting a polishing mold which is matched with the shape of the surface to be processed of the workpiece, and then installing a first polishing leather made of polyurethane on the polishing mold connected with the main shaft;
placing a clamp holding a workpiece on a polishing mold so that a polishing surface of the workpiece is in contact with a first polishing leather surface;
putting down a swing shaft of the high-throwing equipment to enable the swing shaft to be in contact with the clamp;
starting high polishing equipment, driving a polishing mold and a first polishing skin to rotate by a main shaft, simultaneously running a swinging shaft and the main shaft, pressurizing a clamp by a pneumatic system, transferring the clamp to a workpiece, spraying rough polishing liquid onto the first polishing skin by a nozzle, enabling the rough polishing liquid to flow between the workpiece and the first polishing skin, and polishing the surface accuracy delta N of the workpiece is less than or equal to 0.3fr;
carrying out fine polishing on a workpiece:
setting the rotating speed of a main shaft of high-polishing equipment;
a second polishing leather made of polyurethane is arranged on a polishing mould connected with the main shaft;
placing a clamp holding the workpiece subjected to rough polishing on a polishing mold so that a polishing surface of the workpiece is in contact with a second polishing leather surface;
putting down a swing shaft of the high-throwing equipment to enable the swing shaft to be in contact with the clamp;
starting high polishing equipment, driving the polishing mold and the second polishing skin to rotate by the main shaft, simultaneously running the swinging shaft and the main shaft, pressurizing the clamp through the pneumatic system, transferring the clamp to the workpiece, spraying the fine polishing liquid onto the second polishing skin through the nozzle, enabling the fine polishing liquid to flow between the workpiece and the second polishing skin, and finally realizing polishing with the surface roughness RMS of the workpiece being less than or equal to 0.5 nm.
2. The method of high polishing an ultra-smooth surface of an optical element according to claim 1, wherein: in the rough polishing step of the workpiece, the model of the first polishing skin is LP66; the preparation method of the rough polishing liquid comprises the following steps: preparing 2815 polishing powder and purified water according to the specific weight of 1.005-1.01, and gradually adding oxalic acid or sodium hydroxide until the pH value of the prepared mixed solution reaches 6-8.
3. The method of high polishing an ultra-smooth surface of an optical element according to claim 1, wherein: in the step of performing finish polishing on the workpiece, the model of the second polishing skin is LP57 or LASER; the preparation method of the fine polishing liquid comprises the following steps: gradually adding the silica gel solution P-80 or the silica gel solution P-50 and purified water according to the volume of 1: 1.5-2, and gradually adding oxalic acid liquid or sodium hydroxide liquid until the pH value of the prepared mixed solution reaches 7-9.
4. The method of high polishing an ultra-smooth surface of an optical element according to claim 1, wherein: the method for highly polishing the ultra-smooth surface of the optical element further comprises a step of obtaining the initial surface morphology of the workpiece, wherein the step of obtaining the initial surface morphology of the workpiece is positioned before the step of roughly polishing the workpiece, and specifically comprises the following steps: and placing the unpolished workpiece on an objective table, and acquiring the initial surface morphology of the unpolished workpiece by an image acquisition device for comparison analysis with the surface morphology of the workpiece after rough polishing.
5. The method for highly polishing an ultra-smooth surface of an optical element according to claim 4, wherein: the high polishing method for the ultra-smooth surface of the optical element further comprises a surface morphology detection step, wherein the surface morphology detection step is positioned between the rough polishing step and the fine polishing step for the workpiece, and specifically comprises the following steps:
placing the coarsely polished sample to be tested on an objective table, adjusting a light path to enable the sample to be tested and a standard reflector to be positioned at a zero optical path difference position, and scanning the sample to be tested according to a preset scanning path;
the method comprises the steps of obtaining sample light returned by a first light source irradiating a sample to be detected and standard light returned by a second light source irradiating a standard reflector to interfere with each other, and generating sample interference fringes;
sampling the sample interference fringes by utilizing a spectrometer to generate a sample interference spectrum;
performing image processing on the sample interference spectrum to obtain the current surface morphology of the sample to be detected;
and comparing the current surface morphology with the initial surface morphology to obtain the polishing degree of the workpiece to be tested.
6. The method of high polishing an ultra-smooth surface of an optical element according to claim 1, wherein: the high polishing method for the ultra-smooth surface of the optical element further comprises a high-speed fine polishing step for the workpiece, wherein the high-speed fine polishing step for the workpiece is positioned before the rough polishing step for the workpiece, and specifically comprises the following steps of:
determining processing parameters, metal pellets and resin pellets of high-speed fine grinding equipment according to the finished product polishing requirements of the workpiece;
and controlling the low surface shape precision of the workpiece after high-speed finish grinding to be smaller than or equal to a preset value according to the finish grinding processing parameters, and simultaneously controlling the external dimension and the surface roughness of the workpiece to meet the finished product polishing requirement.
7. The method of high polishing an ultra-smooth surface of an optical element according to claim 1, wherein: in the step of rough polishing the workpiece, the polishing removal amount is more than or equal to 0.02nm, and the surface precision delta N is less than or equal to 0.3fr;
in the step of carrying out finish polishing on the workpiece, the polishing removal amount is more than or equal to 0.002nm, and the surface precision delta N is less than or equal to 0.3fr.
8. A high-polishing device for an ultra-smooth surface of an optical element, which is characterized in that: the method for high polishing the ultra-smooth surface of the optical element according to any one of claims 1 to 7 comprises a main shaft, a polishing die, a swinging shaft, a clamp, a first polishing skin, a second polishing skin, a nozzle and a pneumatic system, wherein the main shaft is in transmission connection with the polishing die, the polishing die is matched with the surface of a workpiece in shape, the first polishing skin and the second polishing skin are both made of polyurethane and are fixedly connected with the polishing die, the clamp clamps a workpiece, the swinging shaft is positioned above the clamp, the pneumatic system is used for pressurizing the clamp and the workpiece so that the workpiece is in surface contact with the first polishing skin and the second polishing skin, and the nozzle is used for spraying rough polishing liquid onto the first polishing skin so that the rough polishing liquid flows between the workpiece and the first polishing skin to realize polishing of which the surface precision delta N of the workpiece is less than or equal to 0.3fr; the nozzle is used for spraying the fine polishing liquid onto the second polishing skin, so that the fine polishing liquid flows between the workpiece and the second polishing skin, and finally polishing with the surface roughness RMS of the workpiece being less than or equal to 0.5nm is realized.
9. The ultra-smooth surface blasting apparatus of claim 8, wherein: the first polishing leather and the second polishing leather are detachably arranged on the polishing die.
10. The ultra-smooth surface blasting apparatus of claim 8, wherein: the number of the polishing dies is two, the first polishing leather is adhered to one polishing die, and the second polishing leather is adhered to the other polishing die.
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| CN202311873137.3A CN117733661A (en) | 2023-12-29 | 2023-12-29 | High polishing method and high polishing equipment for ultra-smooth surface of optical element |
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