Processing method of yttrium lutetium silicate crystal

Abstract

The invention relates to a processing method of a lutetium yttrium silicate crystal. The processing method comprises the following steps: selecting a polishing solution; adding a dispersing agent and a pH regulator into the polishing solution; fixing the cut yttrium lutetium silicate crystal on processing equipment; through the steps of the rough polishing stage, the fine polishing stage and the post-treatment stage, the nanoscale surface shape precision RMS can be better than 0.5 nm, the sub-nanoscale surface roughness Ra is smaller than or equal to 0.55 nm, the surface quality of the LYSO crystal is remarkably improved, and the problem that at present, the surface roughness Ra is smaller than or equal to 0.55 nm is solved. The polishing technology for the LYSO crystal mainly comprises traditional mechanical polishing, chemical mechanical polishing is difficult to meet the requirements of the LYSO crystal for high-precision machining and difficult control of technological parameters, the use of chemical reagents may cause pollution to the environment, and the adaptability is poor when the LYSO crystal is in a complex shape. And high-precision deterministic processing cannot be realized.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of crystal processing technology, and particularly to a method for processing yttrium lutetium silicate crystals. Background Technology

[0002] The processing precision of yttrium lutetium silicate (LYSO) crystals has a crucial impact on their performance. For example, surface roughness significantly affects light output efficiency. When surface roughness is high, light scatters at the crystal surface, leading to reduced light output and consequently lower PET imaging sensitivity. Simultaneously, subsurface damage generated during processing also affects electron transport and luminescence processes within the crystal, reducing energy resolution. Currently, polishing techniques for LYSO crystals mainly include conventional mechanical polishing (CMP) and chemical mechanical polishing (CMP). While CMP can reduce surface roughness to some extent, it easily generates mechanical scratches and subsurface damage, making it difficult to meet the high-precision processing requirements of LYSO crystals. CMP utilizes the synergistic effect of chemical reactions and mechanical abrasion; however, its process parameters are difficult to control, and the use of chemical reagents may cause environmental pollution. Furthermore, some existing polishing techniques have poor adaptability to the complex shapes of LYSO crystals (such as aspherical and freeform surfaces), failing to achieve high-precision deterministic processing. Therefore, developing a method that can achieve high-precision, non-destructive processing of LYSO crystals with various shapes is of significant practical importance.

[0003] The processing precision of LYSO crystals has a crucial impact on their performance. For example, surface roughness significantly affects light output efficiency. When surface roughness is high, light is scattered at the crystal surface, leading to reduced light output and consequently lower PET imaging sensitivity. Simultaneously, subsurface damage generated during processing also affects electron transport and luminescence processes within the crystal, reducing energy resolution. Currently, polishing techniques for LYSO crystals mainly include conventional mechanical polishing (CMP) and chemical mechanical polishing (CMP). While CMP can reduce surface roughness to some extent, it easily generates mechanical scratches and subsurface damage, making it difficult to meet the high-precision processing requirements of LYSO crystals. CMP utilizes the synergistic effect of chemical reactions and mechanical abrasion; however, its process parameters are difficult to control, and the use of chemical reagents may cause environmental pollution. Furthermore, some existing polishing techniques have poor adaptability to the complex shapes of LYSO crystals (such as aspherical and freeform surfaces), failing to achieve high-precision deterministic processing. Therefore, developing a method that can achieve high-precision, non-destructive processing of LYSO crystals with various shapes is of significant practical importance.

[0004] Currently, polishing techniques for LYSO crystals mainly include conventional mechanical polishing and chemical mechanical polishing. While conventional mechanical polishing can reduce surface roughness to some extent, it is prone to mechanical scratches and subsurface damage, making it difficult to meet the high-precision machining requirements of LYSO crystals. Chemical mechanical polishing utilizes the synergistic effect of chemical reactions and mechanical abrasion; however, its process parameters are difficult to control, and the use of chemical reagents may cause environmental pollution. Furthermore, some existing polishing techniques have poor adaptability to the complex shapes of LYSO crystals (such as aspherical and free-form surfaces), and cannot achieve high-precision deterministic machining. Summary of the Invention

[0005] The purpose of this invention is to provide a solution that can meet the high-precision machining requirements of LYSO crystals.

[0006] To achieve the above objectives, embodiments of the present invention provide a method for processing yttrium lutetium silicate crystals, comprising the following steps:

[0007] Step S10: Polishing slurry selection; select a polishing slurry; then add a dispersant and a pH adjuster to the polishing slurry; proceed to step S20;

[0008] Step S20: Fix the cut lutetium yttrium silicate crystal onto the processing equipment; proceed to step S30;

[0009] Step S30: Rough Polishing Stage: Fix the cut yttrium lutetium silicate crystals, and use a polishing slurry containing alumina abrasive particles with a particle size of 100-200nm, along with a polyurethane polishing pad, for rough polishing. The polishing pressure is set to 0.3MPa, the rotation speed is 150rpm, and the time is 30-60 minutes to remove the cutting damage layer and achieve a surface roughness of Ra≤2nm. The alumina polishing slurry contains a dispersant, polyacrylic acid or polyethylene glycol, and a pH adjuster, ammonia or citric acid, to maintain the pH value at 9-10. Proceed to Step S40.

[0010] Step S40: Fine polishing stage: Switch to a polishing slurry containing cerium oxide abrasive particles with a particle size of 50-100nm, and perform fine polishing using a magnetorheological polishing device; set the magnetic field strength to 1.2T, the polishing slurry flow rate to 10L / min, and the residence time to 15 seconds / area, reducing the surface roughness to Ra≤0.55nm; the cerium oxide polishing slurry also contains a dispersant, polyacrylic acid or polyethylene glycol, and a pH adjuster, ammonia or citric acid, to maintain the pH value at 9-10; proceed to step S50;

[0011] Step S50: Post-treatment stage: First, use ultrapure water for ultrasonic cleaning at a frequency of 40kHz for 10 minutes to remove residual abrasive particles, and then perform ultraviolet ozone treatment at a wavelength of 185nm and a power of 100W to eliminate organic pollution.

[0012] Furthermore, in the processing method of yttrium lutetium silicate crystals described in this invention, the magnetorheological fluid used in the magnetorheological polishing equipment is composed of magnetic particles, a base liquid, and a stabilizer; the magnetic particles are iron-based or rare earth materials, and the base liquid is an insulating liquid; the iron-based material is Fe3O4; and the base liquid is silicone oil.

[0013] Furthermore, in the processing method of lutetium yttrium silicate crystals described in this invention, before the rough polishing stage in step S30, the lutetium yttrium silicate crystals are cleaned and pretreated to remove surface impurities and oil stains.

[0014] Furthermore, in the processing method of yttrium lutetium silicate crystals described in this invention, the processing steps S20, the rough polishing stage in step S30, the fine polishing stage in step S40, and the post-processing stage in step S50 are all operated in a Class 100 cleanroom to control the cleanliness of the processing environment.

[0015] Furthermore, in the processing method of yttrium lutetium silicate crystals described in this invention, during the fine polishing stage in S40, the path and dwell time of magnetorheological polishing are optimized by computer simulation to achieve more precise material removal and surface quality control.

[0016] Furthermore, in the processing method of lutetium yttrium silicate crystal of the present invention, between the rough polishing stage in step S30 and the fine polishing stage in step S40, the surface roughness and flatness of the lutetium yttrium silicate crystal are detected, and the magnetic field strength, polishing fluid flow rate and residence time of the fine polishing stage are adjusted according to the detection results.

[0017] Furthermore, in the processing method of lutetium yttrium silicate crystals described in this invention, after ultrasonic cleaning with ultrapure water in the post-processing stage, the lutetium yttrium silicate crystals are dried by low-temperature drying or nitrogen blowing.

[0018] Furthermore, in the processing method of yttrium lutetium silicate crystals described in this invention, during the rough polishing stage in step S30 and the fine polishing stage in step S40, the temperature of the polishing slurry is monitored and controlled, and maintained at 20-30°C.

[0019] Furthermore, in the processing method of yttrium lutetium silicate crystals described in this invention, the alumina polishing slurry and cerium oxide polishing slurry are subjected to ultrasonic dispersion treatment before use, with an ultrasonic power of 200W and a time of 30 minutes, and the absolute value of the zeta potential of the abrasive particles is ≥30mV through electrostatic stabilization technology to ensure the dispersion stability of the abrasive particles.

[0020] Furthermore, in the processing method of yttrium lutetium silicate crystals described in this invention, the magnetorheological polishing equipment adopts a magnetic field generating device with a Halbach array design, so that the magnetic field uniformity error is ≤±5%.

[0021] Compared with the prior art, the embodiments of the present invention achieve the following technical effects by selecting a polishing slurry; adding a dispersant and a pH adjuster to the polishing slurry; fixing the cut yttrium lutetium silicate crystals on the processing equipment; and after the rough polishing stage, fine polishing stage, and post-processing stage:

[0022] 1. High-precision processing: By using magnetorheological polishing technology combined with specific alumina and cerium oxide polishing slurries, nanometer-level surface accuracy (RMS better than 0.5nm) and sub-nanometer-level surface roughness (Ra≤0.55nm) can be achieved, significantly improving the surface quality of LYSO crystals, thereby improving light output efficiency and energy resolution.

[0023] 2. Non-destructive processing: The removal force of magnetorheological polishing is transmitted by fluid, which avoids subsurface damage caused by mechanical contact in traditional mechanical polishing. This helps to maintain the integrity of the internal structure of LYSO crystals and improve their performance stability.

[0024] 3. High adaptability: This processing method is not only applicable to the processing of planar LYSO crystals, but also to LYSO crystals with complex shapes such as spherical, aspherical, and freeform surfaces, thus broadening the application range of LYSO crystals in different fields. At the same time, it is compatible with the processing of various optical materials (such as quartz, silicon carbide, sapphire, etc.), demonstrating excellent versatility.

[0025] This invention solves the technical problems of current polishing technologies for LYSO crystals, namely traditional mechanical polishing and chemical mechanical polishing, which are difficult to meet the requirements of high-precision processing and difficult control of process parameters for LYSO crystals. Furthermore, the use of chemical reagents may cause environmental pollution, and the technology is not adaptable to the complex shapes of LYSO crystals (such as aspherical surfaces and freeform surfaces), thus failing to achieve high-precision deterministic processing. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the process of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the various embodiments of this invention will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the various embodiments of this invention to facilitate a better understanding of this application. However, the technical solutions claimed in the claims of this application can be implemented even without these technical details and with various variations and modifications based on the following embodiments.

[0028] The first embodiment of the present invention relates to a method for processing yttrium lutetium silicate crystals, such as... Figure 1 As shown, it includes the following steps:

[0029] Step S10: Polishing slurry selection; then add dispersant and pH adjuster to the polishing slurry; since the density of LYSO crystals is 7.15 g / cm³. 3 It has a melting point of 2050℃, an effective atomic number of 60, a Mohs hardness of 5.8, and a refractive index of 1.82. Its relative luminescence is 65%-75% of that of NaI(T1), with a decay time <45ns, a radiation center wavelength of 420nm, a radiation resistance >1×10 rad, a 511keV gamma-ray attenuation length of 1.2cm, and a 511keV peak resolution of 8%. Regarding the selection of polishing slurry: alumina polishing slurry is chosen. Given that the hardness of LYSO crystals is Mohs 5.8, a polishing slurry with nano-sized alumina abrasive particles is more suitable. Alumina has a high hardness (Mohs 9), and its particle size can be selected between 50nm-200nm. In the rough polishing stage, using alumina polishing slurry in conjunction with a polyurethane polishing pad can effectively remove the cutting damage layer. For example, during coarse polishing, a 100-200nm alumina polishing slurry is used. The dispersant in this slurry (such as PAA or PEG) prevents abrasive particle agglomeration, and the pH adjuster (such as ammonia or citric acid) maintains the pH at 9-10, enhancing the synergistic effect of chemical corrosion. Regarding the selection of cerium oxide polishing slurry: cerium oxide has a lower hardness than alumina (Mohs 7), but it has unique chemical adsorption properties, making it suitable for the fine polishing stage of LYSO crystals. Using a cerium oxide polishing slurry with a particle size of 30nm-150nm can effectively reduce surface roughness during fine polishing. During fine polishing, a 50-100nm cerium oxide polishing slurry is used. Its dispersant and pH adjuster functions similarly to those in alumina polishing slurries, softening the LYSO surface through chemical adsorption, combined with mechanical grinding to achieve efficient removal. Proceed to step S20;

[0030] Step S20: Fix the cut lutetium yttrium silicate crystal onto the processing equipment; proceed to step S30;

[0031] Step S30: Rough Polishing Stage: Fix the cut yttrium lutetium silicate crystals and use a polishing slurry containing alumina abrasive particles with a particle size of 100-200nm, along with a polyurethane polishing pad, for rough polishing. The polishing pressure is set to 0.3MPa, the rotation speed is 150rpm, and the time is 30-60 minutes to remove the cutting damage layer and achieve a surface roughness of Ra≤2nm. The alumina polishing slurry contains a dispersant, polyacrylic acid or polyethylene glycol, and a pH adjuster, ammonia or citric acid, to maintain the pH value at 9-10. Proceed to Step S40.

[0032] Step S40: Fine polishing stage: Switch to a polishing slurry containing cerium oxide abrasive particles with a particle size of 50-100nm, and perform fine polishing using a magnetorheological polishing device; set the magnetic field strength to 1.2T, the polishing slurry flow rate to 10L / min, and the residence time to 15 seconds / area, reducing the surface roughness to Ra≤0.55nm; the cerium oxide polishing slurry also contains the dispersant polyacrylic acid or polyethylene glycol, and the pH adjuster ammonia or citric acid to maintain the pH value at 9-10; proceed to step S50;

[0033] Step S50: Post-treatment stage: First, use ultrapure water for ultrasonic cleaning at a frequency of 40kHz for 10 minutes to remove residual abrasive particles, and then perform ultraviolet ozone treatment at a wavelength of 185nm and a power of 100W to eliminate organic pollution.

[0034] In the above embodiments, by selecting a polishing slurry, adding a dispersant and a pH adjuster to the polishing slurry, fixing the cut yttrium lutetium silicate crystal on the processing equipment, and after the rough polishing stage, fine polishing stage, and post-processing stage, by using magnetorheological polishing technology combined with specific alumina and cerium oxide polishing slurries, nanometer-level surface shape accuracy (RMS better than 0.5nm) and sub-nanometer-level surface roughness (Ra≤0.55nm) can be achieved, significantly improving the surface quality of the LYSO crystal, thereby improving light output efficiency and energy resolution.

[0035] The processing method described in this embodiment is not only applicable to the processing of planar LYSO crystals, but also to LYSO crystals with complex shapes such as spherical, aspherical, and freeform surfaces, thus broadening the application range of LYSO crystals in different fields. Furthermore, it is compatible with the processing of various optical materials (such as quartz, silicon carbide, sapphire, etc.), demonstrating excellent versatility.

[0036] This invention solves the technical problems of current polishing technologies for LYSO crystals, namely traditional mechanical polishing and chemical mechanical polishing, which are difficult to meet the requirements of high-precision processing and difficult control of process parameters for LYSO crystals. Furthermore, the use of chemical reagents may cause environmental pollution, and the technology is not adaptable to the complex shapes of LYSO crystals (such as aspherical surfaces and freeform surfaces), thus failing to achieve high-precision deterministic processing.

[0037] To achieve the aforementioned technical effects, the processing method for yttrium lutetium silicate crystals in this example is as follows: Figure 1 As shown, the magnetorheological fluid used in the magnetorheological polishing equipment consists of magnetic particles, a base fluid, and a stabilizer; the magnetic particles are iron-based or rare-earth materials, and the base fluid is an insulating liquid; the iron-based material is Fe3O4; the base fluid is silicone oil. 1.

[0038] Magnetorheological Polishing Technology Application: Magnetorheological Fluid Composition: Magnetorheological fluids consist of magnetic particles (such as iron-based or rare-earth materials, such as Fe3O4), a base fluid (insulating liquid, such as silicone oil), and stabilizers. In the absence of a magnetic field, the magnetic particles in the magnetorheological fluid are randomly distributed, and the fluid behaves as a flowable liquid. However, under the influence of an applied magnetic field (especially a high-gradient magnetic field), the particles align along the magnetic field lines to form a chain-like structure, causing the liquid to transform into a viscoelastic solid within milliseconds. The magnetorheological fluid forms a "flexible grinding head" with viscoplastic behavior in a gradient magnetic field, generating shear force to remove material through high-speed relative motion with the workpiece surface. Process Parameters: Magnetic field strength is controlled between 0.5-2T (Tesla), dynamically adjusted according to the hardness of the LYSO crystal; polishing fluid flow rate is 5-20L / min to control the uniformity of material removal; residence time is 5-30 seconds per area, optimized through computer simulation. By using magnetorheological polishing, the removal force is transmitted by a fluid, avoiding subsurface damage caused by mechanical contact in traditional mechanical polishing. This helps maintain the integrity of the internal structure of LYSO crystals and improves their performance stability.

[0039] To achieve the aforementioned technical effects, the processing method for yttrium lutetium silicate crystals in this example is as follows: Figure 1 As shown, before the rough polishing stage in step S30, the yttrium silicate crystal is cleaned and pretreated to remove surface impurities and oil.

[0040] To achieve the aforementioned technical effects, the processing method for yttrium lutetium silicate crystals in this example is as follows: Figure 1 As shown, the processing steps S20, S30 (rough polishing stage), S40 (fine polishing stage), and S50 (post-processing stage) are all carried out in a Class 100 cleanroom to control the cleanliness of the processing environment.

[0041] To achieve the aforementioned technical effects, the processing method for yttrium lutetium silicate crystals in this example is as follows: Figure 1 As shown, in the fine polishing stage of S40, the path and residence time of magnetorheological polishing are optimized through computer simulation to achieve more precise material removal and surface quality control.

[0042] To achieve the aforementioned technical effects, the processing method for yttrium lutetium silicate crystals in this example is as follows: Figure 1As shown, between the rough polishing stage in step S30 and the fine polishing stage in step S40, the surface roughness and flatness of the yttrium lutetium silicate crystal are detected, and the magnetic field strength, polishing fluid flow rate and residence time of the fine polishing stage are adjusted according to the detection results.

[0043] To achieve the aforementioned technical effects, the processing method for yttrium lutetium silicate crystals in this example is as follows: Figure 1 As shown, after ultrasonic cleaning with ultrapure water in the post-processing stage, the yttrium silicate crystals are dried by low-temperature drying or nitrogen blowing.

[0044] To achieve the aforementioned technical effects, the processing method for yttrium lutetium silicate crystals in this example is as follows: Figure 1 As shown, during the rough polishing stage in step S30 and the fine polishing stage in step S40, the temperature of the polishing slurry is monitored and controlled, and maintained at 20-30℃.

[0045] To achieve the aforementioned technical effects, the processing method for yttrium lutetium silicate crystals in this example is as follows: Figure 1 As shown, the alumina polishing slurry and cerium oxide polishing slurry are ultrasonically dispersed before use. The ultrasonic power is 200W and the time is 30 minutes. Electrostatic stabilization technology is used to ensure that the absolute value of the zeta potential of the abrasive particles is ≥30mV, so as to ensure the dispersion stability of the abrasive particles.

[0046] To achieve the aforementioned technical effects, the processing method for yttrium lutetium silicate crystals in this example is as follows: Figure 1 As shown, the magnetorheological polishing equipment uses a magnetic field generator designed with a Halbach array, which ensures that the magnetic field uniformity error is ≤±5%.

[0047] In a second embodiment of the present invention, a method for processing yttrium lutetium silicate crystals is also provided, comprising the following steps:

[0048] Step S10: Polishing slurry selection; select a polishing slurry containing alumina abrasive particles with a particle size of 100nm; proceed to step S20;

[0049] Step S20: Fix the cut lutetium yttrium silicate crystal onto the processing equipment; proceed to step S30;

[0050] Step S30: Rough polishing stage: Fix the cut yttrium lutetium silicate crystals and perform rough polishing with a polyurethane polishing pad. The polishing pressure is set to 0.3 MPa, the rotation speed is 150 rpm, and the time is 30 minutes to remove the cutting damage layer and make the surface roughness Ra≤2nm. The alumina polishing solution contains the dispersant polyacrylic acid and the pH adjuster ammonia water to maintain the pH value at 10. Proceed to step S40.

[0051] Step S40: Fine polishing stage: Switch to a polishing slurry containing cerium oxide abrasive particles with a particle size of 50nm, and perform fine polishing using a magnetorheological polishing device; set the magnetic field strength to 1.2T, the polishing slurry flow rate to 10L / min, and the residence time to 15 seconds / area, reducing the surface roughness to Ra≤0.55nm; the cerium oxide polishing slurry also contains the dispersant polyacrylic acid and the pH adjuster ammonia water to maintain the pH value at 10; proceed to step S50;

[0052] Step S50: Post-treatment stage: First, use ultrapure water for ultrasonic cleaning at a frequency of 40kHz for 10 minutes to remove residual abrasive particles, and then perform ultraviolet ozone treatment at a wavelength of 185nm and a power of 100W to eliminate organic pollution.

[0053] The magnetic particles are made of iron-based material Fe3O4; the base liquid is silicone oil.

[0054] Before the rough polishing stage in step S30, the yttrium silicate crystal is cleaned and pretreated to remove surface impurities and oil.

[0055] The processing steps S20, S30 (rough polishing), S40 (fine polishing), and S50 (post-processing) are all carried out in a Class 100 cleanroom to control the cleanliness of the processing environment.

[0056] In the fine polishing stage of S40, the path and residence time of magnetorheological polishing are optimized through computer simulation to achieve more precise material removal and surface quality control.

[0057] Between the rough polishing stage in step S30 and the fine polishing stage in step S40, the surface roughness and flatness of the yttrium silicate crystal are detected, and the magnetic field strength, polishing fluid flow rate and residence time of the fine polishing stage are adjusted according to the detection results.

[0058] After ultrasonic cleaning with ultrapure water in the post-processing stage, the yttrium silicate lutetium crystals are dried by low-temperature drying or nitrogen blowing.

[0059] During the rough polishing stage in step S30 and the fine polishing stage in step S40, the temperature of the polishing slurry is monitored and controlled, and maintained at 20°C.

[0060] Before use, the alumina polishing slurry and cerium oxide polishing slurry are subjected to ultrasonic dispersion treatment with an ultrasonic power of 200W for 30 minutes. Electrostatic stabilization technology is used to ensure that the absolute value of the zeta potential of the abrasive particles is ≥30mV, so as to ensure the dispersion stability of the abrasive particles.

[0061] The magnetorheological polishing equipment uses a magnetic field generator with a Halbach array design, ensuring that the magnetic field uniformity error is ≤±5%.

[0062] In a third embodiment of the present invention, a method for processing yttrium lutetium silicate crystals is also provided, comprising the following steps:

[0063] Step S10: Polishing slurry selection; select a polishing slurry containing alumina abrasive particles with a particle size of 200nm; proceed to step S20;

[0064] Step S20: Fix the cut lutetium yttrium silicate crystal onto the processing equipment; proceed to step S30;

[0065] Step S30: Rough polishing stage: Fix the cut yttrium lutetium silicate crystals and perform rough polishing with a polyurethane polishing pad. The polishing pressure is set to 0.3 MPa, the rotation speed is 150 rpm, and the time is 60 minutes to remove the cutting damage layer and make the surface roughness Ra reach 2 nm. The alumina polishing solution contains the dispersant polyacrylic acid and the pH adjuster ammonia water to maintain the pH value at 9. Proceed to step S40.

[0066] Step S40: Fine polishing stage: Switch to a polishing slurry containing 100nm nano-sized cerium oxide abrasive particles, and perform fine polishing using a magnetorheological polishing device; set the magnetic field strength to 1.2T, the polishing slurry flow rate to 10L / min, and the residence time to 15 seconds / area, reducing the surface roughness to Ra≤0.55nm; the cerium oxide polishing slurry also contains the dispersant polyacrylic acid and the pH adjuster ammonia water to maintain the pH value at 9; proceed to step S50;

[0067] Step S50: Post-treatment stage: First, use ultrapure water for ultrasonic cleaning at a frequency of 40kHz for 10 minutes to remove residual abrasive particles, and then perform ultraviolet ozone treatment at a wavelength of 185nm and a power of 100W to eliminate organic pollution.

[0068] The magnetic particles are made of iron-based material Fe3O4; the base liquid is silicone oil.

[0069] Before the rough polishing stage in step S30, the yttrium silicate crystal is cleaned and pretreated to remove surface impurities and oil.

[0070] The processing steps S20, S30 (rough polishing), S40 (fine polishing), and S50 (post-processing) are all carried out in a Class 100 cleanroom to control the cleanliness of the processing environment.

[0071] In the fine polishing stage of S40, the path and residence time of magnetorheological polishing are optimized through computer simulation to achieve more precise material removal and surface quality control.

[0072] Between the rough polishing stage in step S30 and the fine polishing stage in step S40, the surface roughness and flatness of the yttrium silicate crystal are detected, and the magnetic field strength, polishing fluid flow rate and residence time of the fine polishing stage are adjusted according to the detection results.

[0073] After ultrasonic cleaning with ultrapure water in the post-processing stage, the yttrium silicate lutetium crystals are dried by low-temperature drying or nitrogen blowing.

[0074] During the rough polishing stage in step S30 and the fine polishing stage in step S40, the temperature of the polishing slurry is monitored and controlled, and maintained at 30°C.

[0075] Before use, the alumina polishing slurry and cerium oxide polishing slurry are subjected to ultrasonic dispersion treatment with an ultrasonic power of 200W for 30 minutes. Electrostatic stabilization technology is used to ensure that the absolute value of the zeta potential of the abrasive particles is ≥30mV, so as to ensure the dispersion stability of the abrasive particles.

[0076] The magnetorheological polishing equipment uses a magnetic field generator with a Halbach array design, ensuring that the magnetic field uniformity error is ≤±5%.

[0077] The processing methods for lutetium yttrium silicate crystals in the above embodiments can ultimately reduce the surface roughness to Ra ≤ 0.55 nm, regardless of whether the surface of the lutetium yttrium silicate crystal is a planar, spherical, aspherical, or freeform surface, or other complex shapes. In the second embodiment, the surface roughness is reduced to Ra of 0.50 nm; in the third embodiment, the surface roughness is reduced to Ra of 0.48 nm.

[0078] Those skilled in the art will understand that the above embodiments are specific examples of implementing the present invention, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of the present invention.

Claims

1. A method for processing yttrium lutetium silicate crystals, characterized in that, Includes the following steps: Step S10: Polishing slurry selection; select a polishing slurry; then add a dispersant and a pH adjuster to the polishing slurry; Proceed to step S20; Step S20: Fix the cut lutetium yttrium silicate crystal onto the processing equipment; proceed to step S30; Step S30: Rough Polishing Stage: Fix the cut yttrium lutetium silicate crystals, and use a polishing slurry containing alumina abrasive particles with a particle size of 100-200nm, along with a polyurethane polishing pad, for rough polishing. The polishing pressure is set to 0.3MPa, the rotation speed is 150rpm, and the time is 30-60 minutes to remove the cutting damage layer and achieve a surface roughness of Ra≤2nm. The alumina polishing slurry contains a dispersant, polyacrylic acid or polyethylene glycol, and a pH adjuster, ammonia or citric acid, to maintain the pH value at 9-10. Proceed to Step S40. Step S40: Fine polishing stage: Switch to a polishing slurry containing cerium oxide abrasive particles with a particle size of 50-100nm, and perform fine polishing using a magnetorheological polishing device; set the magnetic field strength to 1.2T, the polishing slurry flow rate to 10L / min, and the residence time to 15 seconds / area, reducing the surface roughness to Ra≤0.55nm; the cerium oxide polishing slurry also contains a dispersant, polyacrylic acid or polyethylene glycol, and a pH adjuster, ammonia or citric acid, to maintain the pH value at 9-10; proceed to step S50; Step S50: Post-treatment stage: First, use ultrapure water for ultrasonic cleaning at a frequency of 40kHz for 10 minutes to remove residual abrasive particles, and then perform ultraviolet ozone treatment at a wavelength of 185nm and a power of 100W to eliminate organic pollution.

2. The processing method for yttrium lutetium silicate crystals according to claim 1, characterized in that, The magnetorheological polishing equipment uses a magnetorheological fluid composed of magnetic particles, a base liquid, and a stabilizer; the magnetic particles are iron-based or rare earth materials, and the base liquid is an insulating liquid; the iron-based material is Fe3O4; and the base liquid is silicone oil.

3. The processing method for yttrium lutetium silicate crystals according to claim 1, characterized in that, Before the rough polishing stage in step S30, the yttrium silicate crystal is cleaned and pretreated to remove surface impurities and oil.

4. The processing method for yttrium lutetium silicate crystals according to claim 1, characterized in that, The processing steps S20, the rough polishing stage in step S30, the fine polishing stage in step S40, and the post-processing stage in step S50 are all carried out in a Class 100 cleanroom, and the cleanliness of the processing environment is controlled.

5. The processing method for yttrium lutetium silicate crystals according to claim 1, characterized in that, In the fine polishing stage of S40, the path and residence time of magnetorheological polishing are optimized by computer simulation to achieve more precise material removal and surface quality control.

6. The processing method of yttrium lutetium silicate crystal according to claim 1, characterized in that, Between the rough polishing stage in step S30 and the fine polishing stage in step S40, the surface roughness and flatness of the yttrium silicate crystal are detected, and the magnetic field strength, polishing fluid flow rate and residence time of the fine polishing stage are adjusted according to the detection results.

7. The processing method of yttrium lutetium silicate crystal according to claim 1, characterized in that, After ultrasonic cleaning with ultrapure water in the post-processing stage, the yttrium silicate crystals are dried using low-temperature drying or nitrogen blowing.

8. The processing method of yttrium lutetium silicate crystal according to claim 1, characterized in that, During the rough polishing stage in step S30 and the fine polishing stage in step S40, the temperature of the polishing slurry is monitored and controlled, and maintained at 20-30℃.

9. The processing method of yttrium lutetium silicate crystal according to claim 1, characterized in that, Before use, the alumina polishing slurry and cerium oxide polishing slurry are subjected to ultrasonic dispersion treatment with an ultrasonic power of 200W for 30 minutes. Electrostatic stabilization technology is used to ensure that the absolute value of the zeta potential of the abrasive particles is ≥30mV, thereby ensuring the dispersion stability of the abrasive particles.

10. The method for processing yttrium lutetium silicate crystals according to claim 2, characterized in that, The magnetorheological polishing equipment employs a magnetic field generator with a Halbach array design, ensuring that the magnetic field uniformity error is ≤±5%.

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