A polishing liquid for processing an ultra-smooth surface of an optical element and a preparation method thereof

Abstract

The application provides a polishing liquid for processing an ultra-smooth surface of an optical element and a preparation method thereof, and relates to the technical field of optical cold working polishing liquids, and comprises 0.5-3% of abrasive, 0.1-0.8% of dispersant, 0.05-0.6% of active agent, 0.1-0.5% of PH regulator, and the rest is deionized water; wherein the abrasive is treated cerium oxide particles with a particle size range of 200-300 nm obtained by a high-speed polishing machine through a wet crushing method, and the particle size range of the high-purity cerium oxide particles is 1-1.5 microns; the dispersant is at least one of sodium hexametaphosphate and polyvinyl pyrrolidone, the active agent is at least one of sodium dodecyl sulfate and polyethylene glycol, and the PH regulator is at least one of tetramethylammonium hydroxide and triethanolamine. The polishing liquid prepared by the abrasive has a narrow particle size distribution, good dispersibility and is not prone to scratches, and can meet the requirement of a laser gyroscope reflector on a surface roughness of better than 0.3 nm.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of optical cold processing polishing liquid, in particular to a polishing liquid for processing an ultra-smooth surface of an optical element and a preparation method thereof. BACKGROUND

[0002] The improvement of the loss index of a high-precision laser gyroscope mirror makes the requirements for the surface roughness and surface defects of a substrate gradually improved during processing. The laser gyroscope mirror requires that the surface roughness be better than 0.3 nm, and the properties of a polishing liquid are one of important factors influencing the polishing surface quality.

[0003] During the polishing process, the particle size, particle shape and hardness of polishing powder all play very important roles, the particle size mainly influences the polishing force, and the largest particle size often plays an important role in scratches on the glass surface. Generally, the polishing liquid for optical processing of optical elements is composed of polishing powder, surfactant, dispersant, deionized water and the like, and is prepared into the polishing liquid through stirring, nitrogen blowing and the like. The particle size distribution of the general polishing liquid is relatively wide, the polishing liquid has poor dispersibility and is prone to scratches, and the polishing liquid is suitable for polishing of general optical elements and cannot meet the requirements of the laser gyroscope mirror for the surface roughness. SUMMARY

[0004] In view of the above defects or deficiencies in the prior art, the application aims to provide a polishing liquid for processing an ultra-smooth surface of an optical element and a preparation method thereof, so as to meet the polishing requirements of the optical element such as the laser gyroscope mirror for the surface roughness.

[0005] In a first aspect, the application provides a polishing liquid for processing an ultra-smooth surface of an optical element, which comprises 0.5-3% of abrasive, 0.1-0.8% of dispersant, 0.05-0.6% of active agent, 0.1-0.5% of PH regulator and the balance of deionized water, based on the total weight of the polishing liquid for processing the ultra-smooth surface of the optical element; wherein the abrasive is treated cerium oxide particles with a particle size range of 200-300 nm obtained by high-speed polishing machine through wet crushing method, the particle size range of the high-purity cerium oxide particles is 1-1.5 microns; the dispersant is at least one of sodium hexametaphosphate and polyvinylpyrrolidone, the active agent is at least one of sodium dodecyl sulfate and polyethylene glycol, and the PH regulator is at least one of tetramethylammonium hydroxide and triethanolamine.

[0006] According to the technical scheme provided in the embodiments of the application, the polishing liquid for processing an ultra-smooth surface of an optical element comprises 0.5-2% of abrasive, 0.1-0.5% of dispersant, 0.1-0.6% of active agent and 0.1-0.5% of PH regulator.

[0007] According to the technical scheme provided in the embodiment of the application, the polishing liquid for super-smooth surface processing of optical elements comprises 1-2% of abrasive, 0.3-0.5% of dispersant, 0.1-0.4% of active agent and 0.1-0.4% of pH regulator.

[0008] According to the technical scheme provided in the embodiment of the application, the polishing liquid for super-smooth surface processing of optical elements comprises 1-2% of abrasive, 0.3-0.5% of dispersant, 0.1-0.4% of active agent and 0.1-0.4% of pH regulator.

[0009] In the second aspect, the application provides a preparation method of the polishing liquid for super-smooth surface processing of optical elements, and the preparation method comprises the following steps:

[0010] The initial suspension is prepared by using high-purity cerium oxide particles with a particle size range of 1-1.5 um;

[0011] The second suspension is obtained by polishing the laser gyroscope mirror with the initial suspension through a high-speed polishing machine and performing wet crushing at the same time;

[0012] The third suspension is obtained by performing first water selection on the second suspension, ultrasonic dispersion of the second suspension, standing and then taking the middle layer solution;

[0013] The fourth suspension is obtained by performing second water selection on the third suspension, ultrasonic dispersion of the third suspension, standing and then taking the middle layer solution;

[0014] The fourth suspension is centrifuged and dried to obtain dried abrasive particles, and the dried abrasive particles are subjected to high-temperature heating treatment to obtain treated cerium oxide particles with a particle size range of 200-300 nm;

[0015] The treated cerium oxide particles, dispersant, active agent, pH regulator and deionized water are mixed and stirred uniformly according to the required concentration to obtain the polishing liquid for super-smooth surface processing of optical elements.

[0016] According to the technical scheme provided in the embodiment of the application, the preparation method of the initial suspension comprises:

[0017] The high-purity cerium oxide particles with a mass of 1 kg and a particle size distribution range of 1-1.5 um, 30 g of dispersant and 15 kg of deionized water are mixed and stirred to obtain the initial suspension;

[0018] Preferably, the stirring speed of the stirrer is 300-400 rpm, and the stirring time is 3-4 hours.

[0019] According to the technical scheme provided in the embodiment of the application, the preparation method of the second suspension comprises:

[0020] The polyurethane polishing disc is installed in the corresponding position of the polishing machine, and then the laser gyroscope mirror disc is placed above the polyurethane polishing disc;

[0021] The initial suspension is continuously delivered to the polishing area between the polyurethane polishing disc and the laser gyroscope mirror disc, the main shaft and the swing shaft of the polishing machine are started, the polyurethane polishing disc is rotated and the laser gyroscope mirror disc is swung, and polishing is performed;

[0022] During the polishing process, the polishing liquid circulates, and the abrasives in the polishing liquid are wet crushed while contacting the mirror surface to obtain a second suspension.

[0023] According to the technical scheme provided in the embodiments of the present application, the preparation method of the third suspension includes:

[0024] The second suspension is ultrasonically dispersed for 15-20 min at an ultrasonic frequency of 40 kHz, and then the middle layer solution is taken after standing for 1 h to obtain the third suspension;

[0025] Preferably, the ultrasonic dispersion time is 20 min.

[0026] According to the technical scheme provided in the embodiments of the present application, the preparation method of the dry abrasive particles includes:

[0027] The fourth suspension is centrifuged and dried at a centrifugal speed of 3000-4000 rpm for 20-30 min;

[0028] Preferably, the centrifugal drying time is 30 min.

[0029] According to the technical scheme provided in the embodiments of the present application, the preparation method of the treated cerium oxide particles includes:

[0030] The dry abrasive particles are heated in a high-temperature furnace, heated to 350-450℃ at a heating rate of 5-7℃ / min, and treated at 350-450℃ for 1.5 h to obtain treated cerium oxide particles;

[0031] Preferably, the heating rate is 6℃ / min, and the temperature is raised to 420℃.

[0032] Compared with the prior art, the application has the beneficial effects that: based on the consideration that the formation of high-quality super-smooth polishing surface is the comprehensive action of mechanical action, physical action and chemical action, the cerium oxide abrasive with uniform particle size distribution and in the range of 200-300 nm is obtained by a high-speed polishing machine in a wet crushing method, in the wet crushing process, the shear force is dominant in the force field, the original high-purity cerium oxide particles are more easily flattened under the shear action, and tend to be spherical, the high-molecular polymers such as sodium hexametaphosphate and polyethylene glycol are selected in the formula to adjust the viscosity of the polishing liquid, to control the evolution of the particle shape to a certain extent, to produce greater damping effect on the movement of the particles, so that the force received by the particles in the crushing process is more uniform and moderate, and finally not only the particle size range of the cerium oxide particles reaches 200-300 nm, but also the irregular structures such as sharp corners on the surface are flattened, and the particle surface morphology tends to be spherical, the polishing liquid prepared by the abrasive has narrow particle size distribution, good dispersibility, and is not easy to produce scratches, and can meet the requirement of the laser gyroscope reflector for the surface roughness of better than 0.3 nm. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The super-smooth surface roughness test graph provided for the embodiment 1 of the application;

[0034] Figure 2 The super-smooth surface roughness test graph provided for the embodiment 2 of the application;

[0035] Figure 3 The super-smooth surface roughness test graph provided for the embodiment 3 of the application;

[0036] Figure 4 The super-smooth surface roughness test graph provided for the embodiment 4 of the application;

[0037] Figure 5 The super-smooth surface roughness test graph provided for the embodiment 5 of the application. DETAILED DESCRIPTION

[0038] The application will be further described in detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related application, and not to limit the application. In addition, it should be noted that only the parts related to the application are shown in the drawings for ease of description.

[0039] It should be noted that the embodiments in the application and the features in the embodiments can be combined with each other without conflict. The application will be described in detail below with reference to the drawings and embodiments.

[0040] As mentioned in the background, in order to solve the problems in the prior art, the present application provides a polishing liquid for super-smooth surface processing of an optical element, wherein the polishing liquid for super-smooth surface processing of the optical element comprises 0.5-3% of abrasive, 0.1-0.8% of dispersant, 0.05-0.6% of active agent, 0.1-0.5% of pH regulator, and the balance is deionized water, based on the total weight of the polishing liquid; wherein the abrasive is treated cerium oxide particles with a particle size range of 200-300 nm obtained by high-speed polishing machine through wet crushing method, the high-purity cerium oxide particles have a particle size range of 1-1.5 μm; the dispersant is at least one of sodium hexametaphosphate and polyvinylpyrrolidone, the active agent is at least one of sodium dodecyl sulfate and polyethylene glycol, and the pH regulator is at least one of tetramethylammonium hydroxide and triethanolamine.

[0041] The preparation method of the polishing liquid for super-smooth surface processing of the optical element comprises the following steps:

[0042] An initial suspension is prepared using high-purity cerium oxide particles with a particle size range of 1-1.5 μm;

[0043] The initial suspension is used to polish a laser gyro reflector by high-speed polishing machine, and wet crushing is performed at the same time to obtain a second suspension;

[0044] The second suspension is subjected to first water selection, ultrasonic dispersion is performed on the second suspension, and then the middle layer solution is taken after standing to obtain a third suspension;

[0045] The third suspension is subjected to second water selection, ultrasonic dispersion is performed on the third suspension, and then the middle layer solution is taken after standing to obtain a fourth suspension;

[0046] The fourth suspension is subjected to centrifugal drying to obtain dried abrasive particles, and the dried abrasive particles are subjected to high-temperature heating treatment to obtain treated cerium oxide particles with a particle size range of 200-300 nm;

[0047] The treated cerium oxide particles are mixed with dispersant, active agent, pH regulator and deionized water according to the required concentration and stirred uniformly to obtain the polishing liquid for super-smooth surface processing of the optical element.

[0048] The preparation method adopts wet crushing of the polishing liquid by high-speed polishing machine, realizes control of the size and surface morphology of the abrasive particles, removes the sharp parts on the surface of large abrasive particles, makes the cutting edges of the abrasive particles smaller, avoids deep scratches on the super-smooth surface, and ensures the polishing effect.

[0049] The particle size distribution is controlled by secondary water selection, the particle size distribution of the polishing liquid is narrowed, the stability of the polishing liquid is improved, the dispersion and suspension of the polishing liquid are improved, the convergence of the surface roughness is facilitated, and a high-quality super-smooth surface is obtained.

[0050] In addition, the concentration of the selected polishing liquid is controlled by centrifugal drying method, and the concentration control is more conducive to the control of the surface roughness. Compared with the spray drying method, the centrifugal drying method is simple and easy to operate.

[0051] Meanwhile, the cerium oxide particles have large specific surface area and high surface energy, and are easily agglomerated in aqueous solution, and the chemical reaction between the particles and the surface of the optical part is insufficient. The use of active agents and dispersants in the polishing liquid can improve the dispersion stability of the polishing liquid, change the surface properties of the abrasive particles, and improve the dispersion uniformity and suspension of the polishing liquid. The use of active agents and dispersants in the polishing liquid can improve the dispersion uniformity and suspension of the polishing liquid. The use of active agents and dispersants in the polishing liquid can improve the dispersion uniformity and suspension of the polishing liquid.

[0052] The above comprehensive effects make the polishing liquid have excellent performance, and is suitable for super-polishing of high-precision laser gyroscope mirrors. The surface defect level reaches 0 level, and the surface roughness RMS is better than 0.3nm.

[0053] Example 1

[0054] S1-1, 1 kg of high-purity cerium oxide particles with a particle size distribution range of 1-1.5 um, 30 g of dispersant and 15 kg of deionized water are mixed and stirred, the stirring speed of the stirrer is 300-400 rpm, and the stirring time is 3-4 hours, to prepare an initial suspension;

[0055] S1-2, the initial suspension is used to polish the laser gyroscope mirror by a high-speed polisher, the polyurethane polishing disc has a diameter of 210 mm, the mirror disc has a diameter of 190 mm, the mirror disc is on the top, the polishing process parameters are: spindle speed 224 r / min, swing frequency 72 times / min, polishing pressure 0.4 MPa, polishing liquid flow rate 4 L / min, wet method crushing, polishing liquid circulation, polishing time 162 h, and the second suspension is obtained;

[0056] S1-3, the second suspension is subjected to first water selection, the suspension is ultrasonically dispersed for 20 min, the ultrasonic frequency is 40 kHz, and after standing for 1 hour, the middle layer solution (2 liters in volume) is taken to obtain a third suspension;

[0057] S1-4, the third suspension is subjected to secondary water selection, and the method is the same as step S1-3 to obtain a fourth suspension;

[0058] S1-5, centrifugal drying of the fourth suspension, centrifugal speed of 3000-4000 rpm, centrifugal drying for 20 min, to obtain the dry abrasive particles and placed in a high temperature furnace heating treatment, 7℃ / min to 350℃, 350℃ heat treatment for 1.5h;

[0059] S1-6, during the solution preparation, the mass percentage of the treated cerium oxide particles, dispersant, active agent and PH regulator is respectively: 0.5% of the abrasive, 0.1% of the dispersant, 0.6% of the active agent and 0.5% of the PH regulator;

[0060] Effect analysis of implementation:

[0061] The application of cerium oxide polishing solution, φ25mm super smooth mirror, after super polishing, with asphalt polishing pad, polishing time 40h, reference Figure 1 , the surface roughness is 0.229nm.

[0062] Example 2

[0063] S2-1, mix 1Kg of high-purity cerium oxide particles with a particle size distribution range of 1-1.5um, 30g of dispersant and 15Kg of deionized water, and stir at a speed of 300-400rpm for 3-4 hours to prepare an initial suspension;

[0064] S2-2, polish the laser gyroscope mirror with the initial suspension by using a high-speed polisher, the polyurethane polishing disc has a diameter of 210mm, the mirror disc has a diameter of 190mm, the mirror disc is on the top, the polishing process parameters are: spindle speed 230r / min, swing frequency 80 times / min, polishing pressure 0.2MPa, polishing liquid flow rate 5L / min, wet method crushing, polishing liquid is recycled, polishing time 168h, to obtain a second suspension;

[0065] S2-3, the second suspension is subjected to first water selection, first ultrasonic dispersion of the suspension, ultrasonic dispersion for 15min, ultrasonic frequency 40kHz; after standing for 1 hour, take the middle layer solution (volume of 2 liters), to obtain a third suspension;

[0066] S2-4, the third suspension is subjected to second water selection, the method is the same as step S1-3, to obtain a fourth suspension;

[0067] S2-5, centrifugal drying of the fourth suspension, centrifugal speed of 3000-4000 rpm, centrifugal drying for 20 min, to obtain the dry abrasive particles and placed in a high temperature furnace heating treatment, 7℃ / min to 350℃, 350℃ heat treatment for 1.5h;

[0068] S2-6, the mass percentage of the treated cerium oxide particles, dispersant, active agent and PH regulator is respectively: 1% of abrasive, 0.5% of dispersant, 0.1% of active agent and 0.4% of PH regulator; S2-7, the polishing liquid is ultrasonically dispersed for 20 minutes before use, and the ultrasonic frequency is 40 kHz.

[0069] Effect analysis of implementation:

[0070] The application of the cerium oxide polishing liquid, the φ25mm super smooth reflector, after super polishing, cooperates with the pitch polishing pad, and the polishing time is 40h, and the reference Figure 2 , the surface roughness is 0.195nm.

[0071] Example 3

[0072] S3-1, 1kg of high-purity cerium oxide particles with a particle size distribution range of 1-1.5um, 30g of dispersant and 15kg of deionized water are mixed and stirred, the stirring speed of the stirrer is 300-400rpm, and the stirring time is 3-4 hours, to prepare an initial suspension;

[0073] S3-2, the initial suspension is used to polish the laser gyroscope reflector through a high-speed polishing machine, the polyurethane polishing disc has a diameter of 210mm, the mirror disc has a diameter of 185mm, the mirror disc is on the top, the polishing process parameters are: the main shaft rotating speed is 240r / min, the swing frequency is 85 times / min, the polishing pressure is 0.3MPa, the polishing liquid flow rate is 6L / min, the wet method is used for crushing, the polishing liquid is recycled, the polishing time is 170h, and the second suspension is obtained;

[0074] S3-3, the second suspension is subjected to first water selection, the suspension is ultrasonically dispersed for 15 minutes, the ultrasonic frequency is 40kHz, and after being static for 1 hour, the middle layer solution (2 liters in volume) is taken to obtain a third suspension;

[0075] S3-4, the third suspension is subjected to second water selection, and the method is the same as that in step S1-3, to obtain a fourth suspension;

[0076] S3-5, the fourth suspension is subjected to centrifugal drying, the centrifugal rotating speed is 3000-4000rpm, the centrifugal drying time is 30min, the dried abrasive particles are obtained and placed in a high-temperature furnace for heating treatment, the temperature is raised to 420℃ at a speed of 6℃ / min, and the heating treatment is performed at 420℃ for 1.5h;

[0077] S3-6, the mass percentage of the treated cerium oxide particles, dispersant, active agent and PH regulator is respectively: 1.5% of abrasive, 0.3% of dispersant, 0.4% of active agent and 0.3% of PH regulator; S3-7, the polishing liquid is ultrasonically dispersed for 20 minutes before use, and the ultrasonic frequency is 40 kHz.

[0078] Effect analysis:

[0079] The application of cerium oxide polishing solution, φ 25 mm super smooth mirror, after super polishing, with pitch polishing pad, polishing time 40 h, reference Figure 3 , the surface roughness is 0.170 nm.

[0080] Example 4

[0081] S4-1, mix 1 kg of high-purity cerium oxide particles with a particle size distribution range of 1-1.5 um, 30 g of dispersant and 15 kg of deionized water, stir the mixture at a speed of 300-400 rpm for 3-4 hours, and prepare an initial suspension;

[0082] S4-2, polish the laser gyro mirror with the initial suspension by using a high-speed polisher, the polyurethane polishing disc has a diameter of 210 mm, the mirror disc has a diameter of 185 mm, the mirror disc is on the top, the polishing process parameters are: spindle speed 245 r / min, swing frequency 88 times / min, polishing pressure 0.3 MPa, polishing liquid flow rate 7 L / min, wet method crushing, polishing liquid recycling, polishing time 170 h, and the second suspension is obtained;

[0083] S4-3, the second suspension is subjected to first water selection, ultrasonic dispersion of the suspension is performed for 20 min at an ultrasonic frequency of 40 kHz; after standing for 1 hour, the middle layer solution (2 liters in volume) is taken to obtain a third suspension;

[0084] S4-4, the third suspension is subjected to second water selection, and the method is the same as step S1-3, to obtain a fourth suspension;

[0085] S4-5, the fourth suspension is subjected to centrifugal drying at a speed of 3000-4000 rpm for 25 min, and the dried abrasive particles are placed in a high-temperature furnace for heat treatment at a speed of 5 ℃ / min to 450 ℃, and heat treatment is performed at 450 ℃ for 1.5 h;

[0086] S4-6, during solution preparation, the mass percentages of the treated cerium oxide particles, dispersant, active agent and PH adjuster are respectively: abrasive 2%, dispersant 0.4%, active agent 0.3%, and PH adjuster 0.1%; S4-7, the polishing solution is ultrasonically dispersed for 10 min before use at an ultrasonic frequency of 40 kHz.

[0087] Effect analysis:

[0088] The application of cerium oxide polishing solution, φ 25 mm super smooth mirror, after super polishing, with pitch polishing pad, polishing time 40 h, reference Figure 4 , the surface roughness is 0.219 nm.

[0089] Example 5

[0090] S5-1, high purity cerium oxide particles with a mass of 1 kg and a particle size distribution range of 1-1.5 um, 30 g of a dispersant, and 15 kg of deionized water were mixed and stirred, the stirring speed of the stirrer was 300-400 rpm, and the stirring time was 3-4 hours to prepare an initial suspension;

[0091] S5-2, the initial suspension was used to polish a laser gyroscope mirror by a high-speed polisher, the polyurethane polishing disc had a diameter of 210 mm, the mirror disc had a diameter of 190 mm, the mirror disc was on top, the polishing process parameters were as follows: spindle speed 248 r / min, swing frequency 78 times / min, polishing pressure 0.35 MPa, polishing liquid flow rate 7 L / min, wet method crushing, polishing liquid circulation, polishing time 170 h, and a second suspension was obtained;

[0092] S5-3, the second suspension was subjected to a first water selection, the suspension was first ultrasonically dispersed for 18 min at an ultrasonic frequency of 40 kHz, and after standing for 1 hour, the middle layer solution (2 liters in volume) was taken to obtain a third suspension;

[0093] S5-4, the third suspension was subjected to a second water selection, and the method was the same as that in step S1-3 to obtain a fourth suspension;

[0094] S5-5, the fourth suspension was subjected to centrifugal drying at a centrifugal speed of 3000-4000 rpm for 28 min to obtain dried abrasive particles, and the abrasive particles were heated in a high-temperature furnace at a speed of 6 ℃ / min to 390 ℃, and then heat-treated at 390 ℃ for 1.5 h;

[0095] S5-6, during solution preparation, the mass percentages of the treated cerium oxide particles, the dispersant, the active agent, and the PH adjuster were as follows: abrasive 3%, dispersant 0.8%, active agent 0.05%, and PH adjuster 0.25%; S5-7, the polishing liquid was ultrasonically dispersed for 10 min before use at an ultrasonic frequency of 40 kHz.

[0096] Effect analysis:

[0097] After the application of the cerium oxide polishing liquid, a φ25 mm super-smooth mirror was polished for 40 h with a pitch polishing pad, and the surface roughness was 0.244 nm. Figure 5

[0098] Table 1 mass composition and implementation effect of examples 1-5

[0099]

[0100] ​As can be seen from Table 1, in the five specific embodiments of the preparation method of the polishing liquid for polishing the super-smooth surface of the optical element, the polishing liquid prepared by the method has a lens surface roughness of the super-smooth mirror below 0.3 nm after polishing the super-smooth mirror using the polishing liquid, indicating that the abrasive of the cerium oxide particles after the treatment of the particle size distribution of 200-300 nm has a structure approaching to a spherical shape, a smooth surface, and the polishing liquid obtained by the synergistic use of the specific dispersing agent, active agent and PH regulator can polish the lens of the super-smooth mirror to meet the use requirements of the lens of the super-smooth mirror.

[0101] The principles and implementation manners of the present application are described by using specific examples in the present text, and the above examples are only used to help understand the method of the present application and its core idea. The above description is only the preferred implementation manner of the present application, and it should be noted that due to the limited expression of the text, there are infinite specific structures in the objective world, and those skilled in the art can make some improvements, decorations or changes without departing from the principles of the present application, or the above technical features can be combined in a proper way; the improvements, decorations, changes or combinations, or the direct application of the inventive concept and technical solution to other occasions without improvement, shall be regarded as the protection scope of the present application.

Claims

1. A method for preparing a polishing liquid for processing an ultra-smooth surface of an optical element, characterized in that: The method comprises the following steps: An initial suspension is prepared using high-purity cerium oxide particles with a particle size range of 1-1.5 μm; A second suspension is obtained by polishing the laser gyroscope mirror with the initial suspension using a high-speed polisher while performing wet crushing; A third suspension is obtained by performing a first water selection on the second suspension, ultrasonic dispersion of the second suspension, and then taking the middle layer solution after standing; A fourth suspension is obtained by performing a second water selection on the third suspension, ultrasonic dispersion of the third suspension, and then taking the middle layer solution after standing; The fourth suspension is subjected to centrifugal drying to obtain dried abrasive particles, and the dried abrasive particles are subjected to high-temperature heating treatment to obtain treated cerium oxide particles with a particle size range of 200-300 nm; The treated cerium oxide particles, a dispersant, an active agent, a pH regulator, and deionized water are mixed and stirred uniformly according to the required concentration to obtain a polishing liquid for super-smooth surface processing of optical elements; The preparation method of the initial suspension comprises: 1 kg of high-purity cerium oxide particles with a particle size distribution range of 1-1.5 μm, 30 g of a dispersant, and 15 kg of deionized water are mixed and stirred to obtain the initial suspension; The preparation method of the treated cerium oxide particles comprises: The dried abrasive particles are placed in a high-temperature furnace for heating treatment, the temperature is raised to 350-450 °C at a temperature rising rate of 5-7 °C / min, and the treated cerium oxide particles are obtained by heating at 350-450 °C for 1.5 h; The polishing liquid for super-smooth surface processing of optical elements comprises 0.5%-3% of abrasive, 0.1%-0.8% of dispersant, 0.05%-0.6% of active agent, 0.1%-0.5% of pH regulator, and the balance of deionized water, wherein the abrasive is treated cerium oxide particles with a particle size range of 200-300 nm obtained by wet crushing of high-purity cerium oxide particles with a particle size range of 1-1.5 μm using a high-speed polisher, the dispersant is at least one of sodium hexametaphosphate and polyvinylpyrrolidone, the active agent is at least one of sodium dodecyl sulfate and polyethylene glycol, and the pH regulator is at least one of tetramethylammonium hydroxide and triethanolamine.

2. The method for preparing a polishing liquid for optical element super-smooth surface processing according to claim 1, characterized by, The polishing liquid for super-smooth surface processing of optical elements comprises 0.5%-2% of abrasive, 0.1%-0.5% of dispersant, 0.1%-0.6% of active agent, 0.1%-0.5% of pH regulator, and the balance of deionized water.

3. The method for preparing a polishing liquid for optical element super-smooth surface processing according to claim 1, characterized by, The polishing liquid for super-smooth surface processing of optical elements comprises 1%-2% of abrasive, 0.3%-0.5% of dispersant, 0.1%-0.4% of active agent, 0.1%-0.4% of pH regulator, and the balance of deionized water.

4. The method for preparing a polishing liquid for optical element super-smooth surface processing according to claim 1, characterized by, The polishing liquid for super-smooth surface processing of the optical element comprises 1-1.5% of abrasive, 0.3-0.5% of dispersant, 0.1-0.4% of active agent, 0.3-0.5% of PH regulator, and the rest is deionized water.

5. The method for preparing a polishing liquid for optical element super-smooth surface processing according to claim 1, characterized by, The preparation method of the second suspension comprises: The polyurethane polishing disc is installed at a corresponding position of the polishing machine, and then the laser gyroscope mirror disc is placed above the polyurethane polishing disc; The initial suspension is continuously delivered to the polishing area between the polyurethane polishing disc and the laser gyroscope mirror disc, the main shaft and the swing shaft of the polishing machine are started, the polyurethane polishing disc is rotated and the laser gyroscope mirror disc is swung, and polishing is performed. During the polishing process, the polishing liquid circulates, and the abrasive in the polishing liquid is wet crushed while contacting the mirror surface to obtain the second suspension.

6. The method for preparing a polishing liquid for optical element super-smooth surface processing according to claim 1, characterized by, The preparation method of the third suspension comprises: The second suspension is ultrasonically dispersed for 15-20 min at an ultrasonic frequency of 40 kHz, and then the middle layer solution is taken after standing for 1 h to obtain the third suspension.

7. The method for preparing a polishing liquid for optical element super-smooth surface processing according to claim 1, characterized by, The preparation method of the dry abrasive particles comprises: The fourth suspension is centrifugally dried at a centrifugal speed of 3000-4000 rpm for 20-30 min.

8. The method for preparing a polishing liquid for optical element super-smooth surface processing according to claim 1, characterized by, The stirring speed of the stirrer during preparation of the initial suspension is 300-400 rpm, and the stirring time is 3-4 hours; the ultrasonic dispersion time of the second suspension is 20 min; the centrifugal drying time of the fourth suspension is 30 min; and the heating rate of the dry abrasive particles in the high-temperature furnace is 6℃ / min, and the temperature is raised to 420℃.

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