Solution-assisted ultra-precision machining method and device for optical crystal

Abstract

The application relates to a solution-assisted ultra-precision machining method and device of an optical crystal. First, the surface to be polished is modified by plasma to make the surface super-hydrophilic; a micro water mist with a certain concentration is formed by mixing gas and micro liquid drops, the micro water mist spreads into a liquid film on the super-hydrophilic surface, the liquid film slightly dissolves the surface of the workpiece and quickly reaches saturation; then, in the process of rotation of the polishing head, the high points are continuously removed and the low points are reserved by relying on the pseudo-random motion between the workpieces, and finally the machining of the ultra-precision surface is realized. The method can not use the polishing pad in the traditional sense, and relies on mutual polishing of the same kind of crystal, so that the one-sided removal of the crystal material caused by the inconsistency of the hardness and other properties between the polishing pad and the crystal can be avoided, and multiple workpieces can be machined at the same time in one machining process, the machining efficiency is improved, and the method is an efficient and low-damage ultra-precision machining method.

Description

Technical Field

[0001] This invention belongs to the field of materials processing and relates to surface polishing technology for optical crystals, especially a solution-assisted ultra-precision processing method for soft and brittle functional crystals that are soluble in water. Background Technology

[0002] Soft and brittle functional optical crystals are a class of optical crystal materials used as optical media. Potassium dihydrogen phosphate (KH2PO4, abbreviated as KDP) is a typical example of a water-soluble, soft and brittle functional optical crystal, characterized by large electro-optic and nonlinear optical coefficients, high laser damage threshold, low optical absorption coefficient, and high transmittance from the near-infrared to the ultraviolet bands. Currently, KDP crystals are the only nonlinear optical crystals that can be used in laser frequency doubling, electro-optic modulation, and optoelectronic switching devices in inertial confinement fusion (ICF) optical path systems. ICF projects require hundreds of large-size (410 mm × 410 mm × 10 mm), ultra-high-quality (nanometer-level surface roughness) KDP crystal components, which places extremely stringent requirements on the growth and processing of KDP crystals. However, KDP crystals are soft, hygroscopic, brittle, and sensitive to temperature changes, which are very unfavorable for their processing. Large-size, high-precision KDP crystal parts are currently recognized as one of the most difficult optical components to process.

[0003] Researchers have conducted extensive studies on the polishing of KDP crystal surfaces, and significant progress has been made in ultra-precision polishing technology for KDP crystals. Currently, KDP crystal surface polishing techniques are mainly divided into two types: contact polishing, such as single-point diamond fly-cut (SPDT), ultra-precision grinding, and magnetorheological polishing; and non-contact polishing, such as laser polishing and ion beam polishing. However, these methods all have certain problems to varying degrees: when processing KDP crystals using ultra-precision grinding, abrasive grains detached from the grinding wheel easily embed into the crystal surface, and are difficult to remove after embedding; when processing crystals using magnetorheological polishing, the residual magnetorheological polishing fluid on the polished surface is difficult to clean; and ion beam polishing has low processing efficiency and high cost. SPDT, as the main processing method for KDP crystals at present, still cannot effectively avoid small-scale ripple defects, resulting in a low laser damage threshold, which seriously affects the performance of KDP crystals.

[0004] Among the previous patented technologies for polishing methods of this type that are soluble in water crystal materials, there are some different types of examples:

[0005] Chinese patent CN101310922A discloses a "Method for Polishing Potassium Dihydrogen Phosphate Crystals by Deliquescence". This method uses a polishing slurry prepared from ethanol and water in a specific ratio to perform ultra-precision polishing on KDP crystals treated with SPDT technology, effectively avoiding the drawback of abrasive grains embedding into the crystal processing surface. However, due to the volatile nature of ethanol, the properties of the polishing slurry can change, thus affecting the processing quality of the crystal surface. Summary of the Invention

[0006] This invention addresses the high requirements for surface roughness and surface accuracy in the application of soft and brittle functional optical crystals, as well as the characteristics of such crystals, such as softness, brittleness, easy solubility in water, and sensitivity to temperature changes. It proposes a solution-assisted ultra-precision mutual polishing method to achieve high-precision, ultra-smooth, low-surface and subsurface damage ultra-precision machining of a class of optical crystals.

[0007] To remove small-scale ripples and other surface and subsurface damage generated during conventional ultra-precision machining, and to prevent the influence of inconsistent hardness between the polishing pad and the crystal to be polished on the surface quality and shape of the crystal during polishing, thus obtaining a high-quality crystal surface that meets the requirements, a solution-assisted ultra-precision mutual polishing method for water-soluble soft and brittle functional optical crystals is proposed.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] The first aspect of this invention is to provide a solution-assisted ultra-precision mutual polishing method for water-soluble, soft, and brittle functional optical crystals.

[0010] The pretreated surface to be polished is treated with plasma in real time, and the high-energy active particles in the plasma are used to modify the surface to be polished into a superhydrophilic state.

[0011] A solution of a certain concentration is prepared using deionized water and the crystal to be polished. Microdroplets of the solution are generated using methods including, but not limited to, direct evaporation and ultrasonic vibration. The microdroplets are mixed evenly with compressed gas to form a micro water mist, which is then added to the surface of the modified superhydrophilic crystal to be polished through a gas delivery pipeline. Due to the superhydrophilicity of the surface, the micro water mist will quickly adsorb onto the crystal surface and form a liquid film. Because the crystal is easily soluble in water, this liquid film will dissolve and soften the surface crystal. At the same time, the part of the liquid film closest to the crystal will first reach saturation. The saturated liquid film will prevent the crystal from dissolving further, making the dissolution rate and amount somewhat controllable. However, this controllability cannot achieve a good level of crystal surface quality. The polishing disc is needed to promote the selectivity and controllability of water mist dissolution.

[0012] The crystals to be polished are fixed onto the polishing head and polishing disc of the polishing mechanism and pressed together under certain pressure. The polishing mechanism is then activated, causing the polishing head to rotate. During polishing, the solution layers at the high points of the crystal surface come into contact with each other. Under the mechanical action of the rotating polishing head, the solution layers at the high points of the crystal are removed, exposing the material at these points. After real-time plasma treatment to modify them into superhydrophilic material, a liquid film reforms on the surface of the high points exposed in the micro-water mist, continuing the dissolution process. The solution layers are then removed again by the mechanical action of the rotating polishing head. The high points gradually decrease in size, achieving selective removal of these high points. Initially, the solution layers at the low points do not come into contact with each other, and the presence of a saturated solution layer limits further dissolution of the crystal at these low points. Once the high points are removed, the entire solution layer begins to come into contact with each other, and the solution layer is removed, achieving global planarization of the polished area of ​​the crystal.

[0013] The optical crystal is a soft and brittle functional optical crystal that is easily soluble in water, such as potassium dihydrogen phosphate crystal, lithium cesium borate crystal, ammonium dihydrogen phosphate crystal, lithium triborate crystal, sodium iodide crystal, potassium bromide crystal, or sodium chloride crystal.

[0014] The pretreatment involves spraying a waterproof membrane, applying a waterproof coating, attaching waterproof tape, or filling the surface of the crystal to be polished, to prevent other parts of the crystal from being dissolved during the polishing process.

[0015] The plasma treatment involves using helium, argon, nitrogen, or other gases to form a layer of hydrophilic groups on the surface of the crystal to be polished, thus transforming the crystal surface into a superhydrophilic state. The compressed gas used is the same as that used in the plasma treatment.

[0016] The solution for polishing the crystal is prepared by mixing deionized water and the crystal in a certain proportion. Different concentrations of solution can be used depending on the required removal rate.

[0017] The micro water mist is a uniform mist mixture generated by mixing microdroplets produced by ultrasonication or other methods with compressed gas using the aforementioned solution. This mixture can remove materials through dissolution. The parameters of the micro water mist have a significant impact on the surface morphology and processing rate of subsequent ultra-precision machining. By adjusting parameters such as the size and density of the microdroplets and the flow rate of the compressed gas, the removal rate, surface accuracy, and surface roughness of the crystals can be adjusted, ultimately resulting in a highly efficient and precise machining process.

[0018] In this polishing process, both the polishing pad and the polishing head are made of the same type of crystal, resulting in mutual polishing of the same crystals. This method overcomes the drawback of using only micro-water mist to achieve a satisfactory surface quality, avoids one-sided material removal caused by the inconsistent hardness between the polishing pad and the workpiece in traditional polishing processes, and also increases processing efficiency.

[0019] A second aspect of the present invention is to provide an apparatus for implementing the above-described method, comprising: a micro water mist generating apparatus, a plasma surface modification apparatus, and an ultra-precision machining apparatus.

[0020] The micro water mist generator mixes microdroplets formed from an aqueous solution of the optical crystal to be polished with compressed gas to form a micro water mist, which is then delivered to the modified, superhydrophilic surface of the optical crystal to be polished via a gas delivery pipeline. The micro water mist generator ensures that the micro water mist uniformly fills the area around the crystal. The micro water mist generator comprises a gas cylinder, a gas delivery pipeline, and a microdroplet generator connected in sequence. The micro water mist is regulated by adjusting the gas flow rate, the amount of microdroplets generated, and the concentration of microdroplets, thereby adjusting the polishing rate and precision. The plasma surface modification device comprises an upper electrode plate, a radio frequency power supply, a radio frequency power matching unit, and a lower electrode plate connected in sequence. The ultra-precision machining device comprises a polishing head and a polishing disc. The polishing head and polishing disc respectively clamp the optical crystal to be polished and perform planetary motion under a certain pressure to achieve ultra-precision machining of the workpiece.

[0021] This device also includes an outer casing and a temperature control device. The outer casing can isolate the workpiece from the external environment to prevent the influence of impurities in the air and changes in ambient temperature on the processing. The temperature control device can ensure the stability of the ambient temperature during polishing and prevent the influence of temperature changes on the dissolution rate and solubility of the crystal.

[0022] Compared with existing patented technologies, the present invention has the following advantages and beneficial effects:

[0023] 1. The solution-assisted mutual polishing method used in this invention removes materials through the dissolution effect of the solution. The mutual polishing of homogeneous crystals promotes the selectivity and controllability of material removal while avoiding damage. It avoids the shortcomings of using only micro water mist dissolution and only using homogeneous crystal mutual polishing, which cannot achieve a good level of surface quality. As a result, a better surface quality is obtained.

[0024] 2. The solution-assisted mutual polishing method used in this invention achieves efficient preparation of ultra-smooth crystal surfaces. In this mutual polishing method, the polishing material and the polished object are the same substance, avoiding one-sided material removal caused by the inconsistent hardness between the polishing pad and the polished object during traditional polishing pad polishing.

[0025] 3. In the method used in this invention, the polishing liquid is a crystal solution of a certain concentration, and both the polishing material and the material being polished are of the same substance, without introducing other impurities. Therefore, the complex cleaning steps that follow are avoided.

[0026] 4. The device of the present invention integrates plasma modification and micro water mist dissolution polishing, realizes real-time plasma modification, ensures that the processed surface is always covered with a liquid film, and improves processing efficiency and accuracy.

[0027] 5. This invention does not involve mechanical processing stress in the traditional sense during the processing and does not produce subsurface damage, making it a truly non-destructive micro-nano fabrication method. Attached Figure Description

[0028] Figure 1 This is a schematic diagram illustrating the material removal and surface planarization principles in this invention.

[0029] Figure 2 The processing technology for ultra-precision machining of optical crystal solutions.

[0030] Figure 3 This is a schematic diagram of the device used in this invention.

[0031] Figure 4 This is a schematic diagram of the planetary motion of the polishing mechanism.

[0032] Figure 5 The results show the surface roughness measurement of the workpiece on the polishing head before the experiment.

[0033] Figure 6 The results show the surface roughness measurement of the workpiece on the polishing pad before the experiment.

[0034] Figure 7 The results show the surface roughness measurement of the workpiece on the polishing head after the experiment.

[0035] Figure 8 The results show the surface roughness measurement of the workpiece on the polishing pad after the experiment.

[0036] Figure 9 The results show the surface roughness measurement after ordinary polishing.

[0037] Figure 10 The results show the surface roughness measurement after dissolution using plasma combined with micro water mist.

[0038] Figure 11 The results show the surface roughness measurement after polishing using plasma combined with micro water mist.

[0039] Figure 12 The surface roughness measurement results are obtained after using micro water mist to dissolve and combine homogeneous crystals for mutual polishing.

[0040] In the diagram: 1. Saturated solution layer; 2. Unsaturated solution layers of different concentrations; 3. High point of the workpiece; 4. Low point of the workpiece; 5. Workpiece; 6. Gas cylinder; 7. Valve; 8. Gas pipeline; 9. Microdroplet generator; 10. Outer shell; 11. Upper electrode plate; 12. Polishing head; 13. Workpiece; 14. Polishing disc; 15. Lower electrode plate; 16. Gas outlet; 17. Radio frequency power supply; 18. Radio frequency power supply matching device; 19. Temperature control device; 20. Insulating support; 21. Revolution direction; 22. Rotation direction; 23. Center of revolution. Detailed Implementation

[0041] The present invention will be further described in detail below through specific embodiments. The following embodiments are merely descriptive and not limiting, and should not be used to limit the scope of protection of the present invention.

[0042] Figure 1 This is a schematic diagram of the technical solution used in this invention. First, a waterproof film is applied to the workpiece to prevent dissolution in other parts of the workpiece. Then, surface modification methods such as plasma are used to modify the surface of the workpiece in real time, making the surface superhydrophilic. Due to the superhydrophilicity of the surface, it can adsorb micro-droplets in the air. The droplets quickly spread on the surface to form a uniform liquid film. Under the action of the liquid film, the workpiece surface undergoes a small amount of dissolution, and a saturated solution layer is quickly formed in the liquid film. This solution layer isolates the crystal surface from the environment, preventing further dissolution of the crystal. However, the liquid film alone cannot achieve a good level of surface quality. The movement of the polishing disc is needed to increase the selectivity and controllability of dissolution. The workpiece, which is fixed on the polishing head and polishing disc respectively, moves planetarily at a certain speed. The solution layers at the high points of the workpiece surface will first come into contact with each other and be removed. Then, the removed parts expose new surfaces, which will continue to form new liquid films in the micro-water mist environment and continue to be removed. The solution layers at the low points do not come into contact with each other at the beginning and will not be removed. At the same time, the presence of the saturated solution layer limits the continued dissolution of the crystals at the low points. Finally, the global flattening of the polished area of ​​the workpiece is achieved. During the high-point removal process, since the two contacting workpieces are made of the same material and have consistent physical and chemical properties, the high points of the upper and lower parts of the workpieces will be removed simultaneously. This avoids problems such as workpiece damage and surface quality degradation caused by inconsistent hardness between the polishing pad and the workpiece during traditional polishing. At the same time, the workpieces on the polishing head and polishing disc are processed simultaneously, improving processing efficiency.

[0043] Figure 2 This is the main process flow used in this invention. (Combined with...) Figure 2The steps of this ultra-precision machining method are described as follows: First, the blank is cut using methods such as diamond wire cutting. A waterproof film is then coated onto the cut blank to prevent other parts of the workpiece from dissolving during machining. Next, surface modification methods such as plasma are used to modify the surface of the workpiece in real time, making the surface to be machined superhydrophilic. Then, a prepared micro-water mist is introduced near the surface to be machined. The micro-droplets in the micro-water mist are adsorbed onto the surface. Due to the superhydrophilicity of the surface, the droplets quickly spread into a uniform liquid film on the workpiece surface. The surface undergoes slight dissolution under the action of the liquid film, rapidly forming a saturated solution layer within the liquid film. This solution layer isolates the crystal surface from the environment, preventing further dissolution. The workpieces, fixed on the polishing head and polishing disc respectively, move in a planetary motion at a certain speed. The solution layers at the high points of the workpiece surface will first come into contact with each other and be removed. Subsequently, the removed parts expose new surfaces, which will continue to form new liquid films in the micro-water mist environment and be removed. Thus, high points are continuously removed, while low points are prevented from being removed due to the saturated solution layer, ultimately achieving global flattening of the polished area of ​​the workpiece.

[0044] Figure 3 A schematic diagram of the processing apparatus for implementing the above method mainly includes the following parts:

[0045] 1. Micro-water mist generator: The micro-water mist generator consists of a gas cylinder 6, a valve 7, a gas supply line 8, and a micro-droplet generator 9 connected in sequence. This device can regulate the micro-water mist by adjusting the gas flow rate, the amount of micro-droplets generated, and the concentration of micro-droplets, thereby adjusting the polishing rate and precision. The gas cylinder contains plasma modification gases, such as helium, argon, and nitrogen.

[0046] 2. Ultra-precision machining device: The ultra-precision machining device includes a housing 10, a polishing head 12, a workpiece 13, upper and lower polishing discs 14, an air outlet 16, and a temperature control device 19. The air outlet 16 is formed on the housing 10, and the temperature control device 19 is installed inside the housing. The housing 10 can prevent changes in external ambient temperature and humidity from affecting the machining process, and also prevent external impurities from contaminating the workpiece surface. The polishing head 12 and polishing discs 14 can stably hold the workpiece to be polished and enable the workpiece 13 to perform planetary motion under a certain pressure, achieving ultra-precision machining of the workpiece. The upper and lower polishing discs 14 are driven by motors (not shown in the figure).

[0047] 3. Plasma Surface Modification Device: The plasma surface modification device includes an upper electrode plate 11, an RF power supply 17, an RF power supply matching device 18, and a lower electrode plate 15 connected in sequence. The upper and lower electrode plates can be set to be fixed or rotate with the upper and lower polishing discs. Therefore, the upper and lower electrode plates can be fixed on the insulating support 20, or on the upper and lower polishing discs, respectively. The upper and lower electrode plates are connected to the RF power supply and the RF power supply matching device through wires.

[0048] Figure 4 This is a schematic diagram of a planetary motion of a polishing mechanism. The polishing head 12 performs planetary motion relative to the polishing disk 14, and while rotating on its own axis, it also revolves around the center of revolution 23 with a certain radius.

[0049] To demonstrate the effectiveness of the proposed method, experiments were conducted on solution-assisted ultra-precision mutual polishing of KDP crystals (a typical water-soluble, soft, and brittle functional optical crystal) and polishing experiments using other methods.

[0050] Example 1

[0051] An experiment on solution-assisted ultra-precision mutual polishing was conducted. The polishing pressure was 600 g, the polishing time was 30 min, the polishing disc rotation speed was 30 rpm, the polishing solution was an aqueous solution of KDP crystal, the micro water mist addition rate was 0.5 ml / min, the lower polishing pad material was homogeneous KDP crystal, the plasma modification gas was argon, and the power was 40 W.

[0052] The surface roughness of the KDP crystal before and after processing was observed using a white light interferometer to obtain information. The results are as follows: Figure 5-8 As shown. Among them Figure 5 and Figure 6 The figure shows the surface roughness measurements of the KDP crystals on the polishing head and polishing disc before processing. As can be seen from the figure, the surface roughness of both KDP crystals is approximately 20 nm (Sa). Figure 7 , 8 After solution-assisted ultra-precision mutual polishing experiments, the surface roughness of the two KDP crystals were 1.23 nm (Sa) and 1.23 nm (Sa), respectively, which significantly reduced the surface roughness compared with that before processing.

[0053] Comparative Example 1

[0054] Ordinary polishing was used, with a polishing pressure of 600 g, a polishing time of 30 min, a polishing disc rotation speed of 30 rpm, an oil-based polishing slurry with ethylene glycol as the base, cerium dioxide as the abrasive particles with a mass fraction of 1%, and an addition rate of 0.5 ml / min via dropwise addition. The lower polishing pad was made of polyurethane. Figure 9The measurement results are after ordinary polishing, with a surface roughness of 4.19 nm (Sa).

[0055] Comparative Example 2

[0056] The difference from Example 1 is that the micro water mist generator and plasma generator are turned on, but the ultra-precision machining device is not turned on.

[0057] The addition rate of the micro water mist was 0.5 ml / min, the plasma modification gas was argon, and the power was 40 W. Figure 10 The surface measurement results were obtained by using plasma combined with micro water mist dissolution, which could not achieve a good surface quality, with a surface roughness of 238 nm (Sa).

[0058] Comparative Example 3

[0059] The difference from Example 1 is that the polishing material of the polishing pad is not a homogeneous crystal, but a polyurethane polishing pad.

[0060] The polishing pressure was 600 g, the polishing time was 30 min, the polishing disc rotation speed was 30 rpm, the polishing fluid was an aqueous solution of KDP crystals, the micro water mist addition rate was 0.5 ml / min, the lower polishing pad material was polyurethane, the plasma modification gas was argon, and the power was 40 W.

[0061] Figure 11 The surface roughness measurement results are obtained by using plasma combined with micro water mist to dissolve and polish the surface, which cannot achieve a good surface quality.

[0062] Comparative Example 4

[0063] The difference from Example 1 is that the ultra-precision machining device and the micro water mist generator are turned on, but the plasma surface modification device is not turned on.

[0064] The polishing pressure was 600 g, the polishing time was 30 min, the polishing disc rotation speed was 30 rpm, the polishing fluid was an aqueous solution of KDP crystals, the addition rate of the polishing fluid was 0.5 ml / min, and the material of the lower polishing pad was homogeneous KDP crystals.

[0065] Figure 12 The surface measurement results are obtained after dissolving and polishing homogeneous crystals using micro water mist. The surface roughness is 8.22 nm (Sa), which also fails to achieve a good surface quality.

[0066] Comparative Example 5

[0067] The difference from Example 1 is that the ultra-precision machining device and the plasma surface modification device are turned on, but the micro water mist generator is not turned on.

[0068] The polishing pressure was 600 g, the polishing time was 30 min, the polishing disc rotation speed was 30 rpm, the lower polishing pad material was homogeneous KDP crystal, the plasma modification gas was argon, and the power was 40 W.

[0069] The surface is scratched and cracked due to mechanical removal, making it impossible to achieve a good surface quality.

[0070] The above examples and comparative examples demonstrate that this solution-assisted mutual polishing method can significantly improve the surface roughness of the workpiece. The results are not only superior to ordinary polishing, but also superior to the surface treated with plasma combined with micro-water mist dissolution, and superior to the results of micro-water mist dissolution combined with homogeneous crystal mutual polishing. Furthermore, it does not introduce other substances that could cause surface contamination. Simultaneously, the two KDP crystals involved in the mutual polishing are processed, improving processing efficiency. It is suitable for ultra-precision surface processing of soft and brittle functional optical crystals that are soluble in water. Table 1 also compares the experimental results of water-based dissolution polishing for several other crystals (lithium cesium borate, ammonium dihydrogen phosphate, potassium dideuterium phosphate, lithium triborate, sodium iodide, potassium bromide, and sodium chloride).

[0071] Table 1 Deliquescent crystals that can be processed with solution assistance

[0072]

[0073] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several modifications and improvements can be made without departing from the inventive concept, and these all fall within the protection scope of the present invention.

Claims

1. A solution-assisted ultra-precision machining method for optical crystals, characterized in that, The surface of the optical crystal to be polished is modified into a superhydrophilic state by using plasma to process the pretreated optical crystal surface in real time. A solution of a certain concentration is prepared using deionized water and the optical crystal to be polished, and the solution is made into microdroplets. The microdroplets are mixed with compressed gas to form micro water mist, which is then delivered to the surface of the modified superhydrophilic optical crystal to be polished through a gas delivery pipeline. The micro water mist is adsorbed on the surface of the optical crystal and forms a liquid film. This liquid film can dissolve and soften the surface of the optical crystal. The optical crystal to be polished is fixed on the polishing head and polishing disc of the polishing mechanism and pressed together with a certain pressure for polishing.

2. The solution-assisted ultra-precision machining method for optical crystals according to claim 1, characterized in that, The optical crystal is a potassium dihydrogen phosphate crystal, a lithium cesium borate crystal, an ammonium dihydrogen phosphate crystal, a lithium triborate crystal, a sodium iodide crystal, a potassium bromide crystal, or a sodium chloride crystal.

3. The solution-assisted ultra-precision machining method for optical crystals according to claim 1, characterized in that, The pretreatment involves spraying a waterproof membrane, applying a waterproof coating, attaching waterproof tape, or filling the crystal with waterproof material around it to be polished.

4. The solution-assisted ultra-precision machining method for optical crystals according to claim 1, characterized in that, The gases used in real-time plasma processing are helium, argon, and nitrogen.

5. The solution-assisted ultra-precision machining method for optical crystals according to claim 4, characterized in that, The compressed gas is the same gas used in plasma processing.

6. The solution-assisted ultra-precision machining method for optical crystals according to claim 1, characterized in that, Microdroplets are formed by direct evaporation or ultrasonic oscillation.

7. The solution-assisted ultra-precision machining method for optical crystals according to claim 1, characterized in that, The removal rate, surface accuracy, and surface roughness of crystals can be adjusted by regulating the size and density of microdroplets and the flow rate of compressed gas.

8. A processing apparatus for implementing the solution-assisted ultra-precision processing method for optical crystals according to any one of claims 1-7, characterized in that, include: The micro water mist generator mixes micro droplets formed from the aqueous solution of the optical crystal to be polished with compressed gas to form micro water mist, which is then delivered to the modified superhydrophilic surface of the optical crystal to be polished through a gas guide pipe. Plasma surface modification device: comprising an upper electrode plate, a radio frequency power supply, a radio frequency power supply matching unit, and a lower electrode plate connected in sequence; And an ultra-precision machining device: including a polishing head and a polishing disc, wherein the polishing head and the polishing disc respectively clamp the optical crystal to be polished and perform planetary motion under a certain pressure to achieve ultra-precision machining of the workpiece.

9. The processing apparatus according to claim 8, characterized in that, It also includes the outer casing and a temperature control device.

10. The processing apparatus according to claim 8, characterized in that, The micro water mist generator includes a gas cylinder, a gas pipeline, and a micro droplet generator connected in sequence. The micro water mist is adjusted by regulating the gas flow rate, the amount of micro droplets generated, and the concentration of micro droplets, thereby adjusting the polishing rate and precision.

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