Plasma in-situ activation and optical element polishing system and method

Abstract

The application relates to the technical field of optical processing, in particular to a plasma in-situ activation and optical element polishing system and a polishing method. The system comprises two multi-degree-of-freedom robots, a workpiece table, an optical element to be processed, a plasma tool head, a polishing tool head and a central cooperative control module. The method is realized based on the system, initial surface error data of the optical element is acquired, a machining path shared by the two robots is planned, and a cooperative feeding speed is calculated. The plasma tool head is controlled to firstly perform in-situ activation processing on the optical element, the polishing tool head is controlled to be located at a safe distance position from the plasma tool head under the constraint of a constructed time phase difference control equation, and the machining is completed within an effective time window in which the surface activity of the optical element has not been significantly attenuated. The application eliminates dry friction disturbance on the surface of the optical element, effectively guarantees material removal consistency, and significantly improves the machining precision of the optical element.

Description

Technical Field

[0001] This invention belongs to the field of optical processing technology, and particularly relates to a plasma in-situ activation and optical element polishing system and polishing method. Background Technology

[0002] In the field of ultra-precision manufacturing of high-end optical systems, multi-degree-of-freedom industrial robots equipped with flexible polishing tools have become the mainstream forming process for high-precision optical components, performing polishing of complex curved surfaces. This process generally employs Computer Controlled Optical Surfacing (CCOS) technology to achieve deterministic material removal. Its core principle follows the Preston equation, which states that the material removal rate of optical components is positively correlated with the processing contact pressure, the relative linear velocity of the tool and workpiece, and the Preston constant. The Preston constant is determined by the physicochemical properties of the polishing slurry and the grinding media, and its spatial uniformity depends entirely on the adhesion and spreading state of the polishing slurry on the workpiece surface, making it a key factor determining the accuracy and surface quality of the polished surface.

[0003] Stable ultra-precision polishing requires the polishing slurry to form a continuous, uniform, and controllable thickness hydrodynamic lubricating film on the workpiece surface to ensure consistent material removal characteristics in the processing area. However, commonly used high-performance optical substrates such as silicon carbide, fused silica, and microcrystalline glass generally have low surface energy, strong chemical inertness, and significant hydrophobic properties, making it difficult for the polishing slurry to wet and spread. In the fine polishing stage, the surface roughness of the workpiece is reduced to the nanometer or even sub-nanometer level, and the surface micro-liquid storage structure completely disappears, further deteriorating the wetting conditions. At the same time, after high-energy beam treatment such as ion beam shaping, the original hydrophilic hydration structure of the optical surface is completely stripped away, forming a superhydrophobic dense surface. Under these extreme conditions, the polishing slurry is prone to aggregation, slippage, and loss, making it impossible to build a stable hydrodynamic film, resulting in uneven material removal. This severely limits the processing accuracy and stability of robotic deterministic polishing and is a major technical bottleneck in the ultra-precision manufacturing of high-end optical components.

[0004] Current mainstream processing solutions for addressing the aforementioned wetting challenges have inherent technical flaws, making it difficult to meet the demands for high-precision and high-consistency polishing. Existing conventional processing methods involve single-robot mechanical polishing, which supplies the polishing area solely through external nozzles on the machine tool or water outlets at the spindle center, relying on flexible tools for direct polishing. Due to the natural hydrophobicity of optical substrates, the polishing fluid has a large contact angle and poor spreadability, making it prone to loss under the centrifugal force of high-speed tool rotation. This makes it difficult to maintain a stable and uniform lubricating film in the processing contact area, often resulting in localized lubrication deficiencies. This uneven wetting problem leads to discrete abrasive grain distribution in the processing area, causing distortion and real-time fluctuations in the CCOS removal function, significantly reducing the execution accuracy of the dwell time algorithm, and limiting surface convergence efficiency and forming accuracy. Simultaneously, localized dry friction and micro-friction easily induce surface micro-cracks, increasing the risk of high-frequency roughness deviations and making it difficult to achieve nanoscale ultra-precision surface processing effects.

[0005] To improve surface wettability, existing high-precision processes employ intermittent polishing schemes with offline plasma activation pretreatment. This involves implanting hydrophilic functional groups into the workpiece surface through offline cleaning or plasma treatment, temporarily increasing the surface energy before transfer and clamping for polishing. However, high-energy optical surfaces activated by high energy are in a metastable state and rapidly adsorb water vapor and hydrocarbon pollutants in the atmosphere, resulting in hydrophobic recovery. The hydrophilic modification effect has a strict time window. Since offline activation and online polishing processes are independent, the workpiece requires multiple steps such as unloading, transfer, clamping, and alignment. The intervals between these steps far exceed the effective aging time of activation. Before processing, the surface hydrophilicity has significantly decreased, the wetting performance of the polishing fluid has markedly declined, and the pretreatment modification effect is essentially ineffective. This makes it impossible to guarantee fluid film uniformity and material removal consistency throughout the polishing process, and fails to fundamentally solve the problem of stable polishing of superhydrophobic optical surfaces.

[0006] In summary, existing robotic polishing technologies have significant drawbacks. Purely mechanical polishing struggles to maintain liquid film stability and uniformity of the removal function, limiting processing accuracy. Offline activation polishing suffers from aging degradation and process sequence discontinuity, hindering the effective implementation of modification effects. Neither of these technical solutions can simultaneously meet the ultra-precision processing requirements of real-time wetting modification of superhydrophobic optical surfaces, overall fluid film stability, and uniform material removal, making them unsuitable for the high-precision manufacturing conditions of high-end optical components. Therefore, there is an urgent need in this field for an integrated collaborative processing solution combining surface activation and precision polishing to effectively overcome the problem of surface energy aging degradation and ensure stable and unified surface wetting state and material removal characteristics throughout the polishing process. Summary of the Invention

[0007] In view of this, the present invention aims to provide a plasma in-situ activation and optical element polishing system and polishing method, so as to construct a uniform fluid film and complete the polishing process within the effective time window of the plasma activation surface, eliminate dry friction disturbance on the surface of the optical element during the processing, ensure the consistency of material removal, and improve the processing accuracy of the optical element.

[0008] To achieve the above objectives, the technical solution created by this invention is implemented as follows: A plasma in-situ activation and optical element polishing system includes two multi-degree-of-freedom robots and a workpiece stage; optical elements to be processed are fixedly clamped on the workpiece stage. The plasma in-situ activation and optical component polishing system also includes: a plasma tool head, a polishing tool head, and a central collaborative control module; The plasma tool head is fixedly mounted on the end effector of one of the multi-degree-of-freedom robots to excite plasma jets and perform in-situ plasma activation treatment on the surface of optical components. The polishing tool head is fixedly mounted on the end effector of another multi-degree-of-freedom robot and is used to polish the surface of optical components after plasma in-situ activation treatment. The central collaborative control module is connected to two multi-degree-of-freedom robots, a plasma tool head, and a polishing tool head via an industrial communication bus, and performs unified collaborative control over the motion trajectory and timing of the multi-degree-of-freedom robots, as well as the process parameters of the plasma tool head and the polishing tool head.

[0009] Furthermore, the plasma tool head integrates a gas supply unit, which provides protective gas while the plasma tool head generates the plasma jet.

[0010] Furthermore, the plasma tool head can be any one of an atmospheric pressure rotating plasma generator, a linear plasma array generator, a microwave plasma generator, or a dielectric barrier discharge plasma generator.

[0011] Furthermore, the polishing tool head integrates a polishing fluid supply unit and a force sensor; The polishing slurry supply unit is used to supply polishing slurry; Force sensors are used to control the normal contact pressure of the polishing tool head.

[0012] Furthermore, the polishing tool head can be any one of bonded abrasive tools, flexible and semi-rigid tools, or special energy field-assisted tools; The bonded abrasive tool is any one of diamond grinding wheels, resin / metal bonded grinding heads, or ball end mills; Flexible and semi-rigid tools are any one of abrasive belts, polishing belts, airbag polishing tools, and asphalt polishing discs; The special energy field auxiliary tool is either a magnetorheological polishing head or a liquid jet polishing head.

[0013] Furthermore, the central collaborative control module includes a trajectory planning unit, a motion constraint control unit, and a process parameter control unit; The trajectory planning unit is used to plan the collaborative processing trajectory of a multi-degree-of-freedom robot; The motion constraint control unit is used to control the running trajectory and running sequence of a multi-degree-of-freedom robot; The process parameter control unit is used to control the plasma process parameters of the plasma tool head and the process parameters of the polishing tool head.

[0014] Furthermore, the surface shape of the optical element can be any one of a plane, sphere, aspherical surface, or freeform surface; the material of the optical element can be any one of silicon carbide, fused silica, K9 glass, microcrystalline glass, silicon single crystal, germanium single crystal, or calcium fluoride.

[0015] Furthermore, a multi-degree-of-freedom robot can be any one of a multi-axis industrial robot or a multi-degree-of-freedom robotic arm that possesses multi-dimensional spatial motion capabilities.

[0016] A method for in-situ plasma activation and optical element polishing, based on the aforementioned in-situ plasma activation and optical element polishing system, includes the following steps: S1: Perform global calibration of the workpiece coordinate system and robot coordinate system to obtain the initial surface shape error data of the optical component to be processed. Plan a processing path shared by two multi-degree-of-freedom robots on the surface of the optical component. Calculate the surface shape gradient based on the initial surface shape error data, and then calculate the cooperative feed rate of the two multi-degree-of-freedom robots based on the surface shape gradient. ; S2: Control the plasma tool head to travel to the starting point of the machining path. The plasma tool head excites the plasma jet with preset plasma process parameters and feeds at a coordinated speed. The optical element is tangentially fed along the processing path to perform in-situ plasma activation treatment on its surface, forming an activation region. S3: Set the actual physical offset distance between the plasma tool head and the polishing tool head to... Its safe distance threshold is ,and satisfy ,in, For timeliness and safety factor and , The effective time window for activating the region; the time it takes for the polishing tool head to travel to the same processing point as the plasma tool head is defined as the time lag. Construct the time phase difference control equation: ; S4: Under the constraint and control of the time phase difference control equation, the polishing tool head feeds at a cooperative feed rate. Upon reaching the activation zone, polishing liquid is sprayed onto the zone, forming a fluid film on the surface of the activation zone. The polishing tool head then polishes the fluid film using preset polishing process parameters.

[0017] Furthermore, the plasma process parameters include the power and frequency of the plasma jet excitation; the polishing process parameters include the polishing speed and normal contact pressure.

[0018] Compared with the prior art, the present invention can achieve the following beneficial effects: (1) The present invention adopts a collaborative processing mode combining plasma in-situ activation and polishing. It first uses a plasma tool head to perform in-situ activation treatment on the surface of optical components, reducing the contact angle of the processing area to a superhydrophilic state, which promotes the formation of a uniform and continuous fluid film in the activation area of ​​the polishing liquid, completely eliminating the dry friction disturbance on the surface of the optical components, effectively ensuring the consistency of material removal, and significantly improving the processing accuracy of the optical components. At the same time, the present invention overcomes the problems of long process chains and secondary clamping errors caused by multiple loading and unloading caused by traditional single machine tools that can only perform a single task, and greatly shortens the manufacturing cycle of large-diameter or complex curved surface optical components.

[0019] (2) By constructing a time phase difference control equation, the present invention ensures that the time lag of the polishing tool head is less than the effective time window of the plasma in-situ activation treatment, thus ensuring that the polishing tool head completes the processing within the effective time before the surface activity of the optical element has significantly decreased. This fundamentally avoids the risk of aging and failure of the activated area of ​​the optical element surface under natural conditions and ensures the process effect of plasma modification. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 A schematic diagram of the structure of the plasma in-situ activation and optical element polishing system described in the embodiments of the present invention; Figure 2 This is a schematic flowchart of the plasma in-situ activation and optical element polishing method described in the embodiments of the present invention.

[0021] Explanation of reference numerals in the attached figures: 1. First robot; 2. Second robot; 3. Workpiece stage; 4. Optical components; 5. Plasma tool head; 6. Polishing tool head; 7. Central collaborative control module. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0023] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0024] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0025] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0026] The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0027] like Figure 1 As shown, this embodiment of the invention provides a plasma in-situ activation and optical element polishing system, including two multi-degree-of-freedom robots and a workpiece stage 3; the two multi-degree-of-freedom robots are a first robot 1 and a second robot 2; the optical element 4 to be processed is fixedly clamped on the workpiece stage 3.

[0028] The plasma in-situ activation and optical component polishing system also includes: a plasma tool head 5, a polishing tool head 6, and a central collaborative control module 7; The plasma tool head 5 is fixedly mounted on the end effector of the first robot 1 and is used to generate a plasma jet to perform in-situ plasma activation treatment on the surface of the optical element 4. The plasma tool head 5 integrates a gas supply unit, which is used to provide protective gas while the plasma tool head 5 generates the plasma jet.

[0029] In some embodiments, the plasma tool head 5 is any one of an atmospheric pressure rotating plasma generator, a linear plasma array generator, a microwave plasma generator, or a dielectric barrier discharge plasma generator.

[0030] The polishing tool head 6 is fixedly mounted on the end effector of the second robot 2 and is used to polish the surface of the optical element 4 after plasma in-situ activation treatment. The polishing tool head 6 integrates a polishing slurry supply unit and a force sensor. The polishing slurry supply unit is used to supply polishing slurry. The force sensor is used to control the normal contact pressure of the polishing tool head 6.

[0031] In some embodiments, the polishing tool head 6 is any one of bonded abrasive tools, flexible and semi-rigid tools, and special energy field-assisted tools; further, the bonded abrasive tool is any one of diamond grinding wheels, resin / metal bonded grinding heads, and ball end mills; the flexible and semi-rigid tools are any one of abrasive belts, polishing belts, airbag polishing tools, and asphalt polishing discs; and the special energy field-assisted tools are any one of magnetorheological polishing heads and liquid jet polishing heads.

[0032] The central collaborative control module 7 is connected to the first robot 1, the second robot 2, the plasma tool head 5, and the polishing tool head 6 via an industrial communication bus, and performs unified collaborative control on the motion trajectory and motion sequence of the first robot 1 and the second robot 2, as well as the process parameters of the plasma tool head 5 and the polishing tool head 6.

[0033] The central collaborative control module 7 includes a trajectory planning unit, a motion constraint control unit, and a process parameter control unit; the trajectory planning unit is used to plan the collaborative processing trajectory of the first robot 1 and the second robot 2; the motion constraint control unit is used to control the running trajectory and running sequence of the first robot 1 and the second robot 2; the process parameter control unit is used to control the plasma process parameters of the plasma tool head 5 and the process parameters of the polishing tool head 6.

[0034] In some embodiments, the surface shape of the optical element 4 is any one of a plane, a sphere, an aspherical surface, or a freeform surface; the material of the optical element 4 is any one of silicon carbide, fused silica, K9 glass, microcrystalline glass, silicon single crystal, germanium single crystal, or calcium fluoride.

[0035] This invention employs a synergistic processing mode combining in-situ plasma activation and polishing. Before the polishing tool head 6 is used, a high-frequency non-equilibrium plasma jet is first sprayed onto the surface of the optical element 4, which is in a hydrophobic and inert state, using the plasma tool head 5. This breaks the chemical inertness of the optical element 4 material, instantly reduces the contact angle of the polishing slurry on the surface of the optical element 4, and constructs high-energy superhydrophilic boundary conditions that meet the requirements for good spread of the polishing slurry. This achieves in-situ plasma activation modification of the surface of the optical element 4, overcomes the spatiotemporal disconnect problem caused by traditional offline activation, eliminates dry friction and microscopic thermal stress caused by local shortage of polishing slurry, ensures the consistency of material removal, and improves the processing accuracy of large-diameter or complex curved optical elements 4.

[0036] In some embodiments, a multi-degree-of-freedom robot is either a multi-axis industrial robot or a multi-degree-of-freedom robotic arm capable of multi-dimensional spatial motion. Alternatively, a multi-degree-of-freedom robot can be equivalently replaced by a multi-axis CNC machine tool.

[0037] like Figure 2 As shown, combined with Figure 1 This invention also provides a method for in-situ plasma activation and optical element polishing, based on the above-described in-situ plasma activation and optical element polishing system, comprising the following steps: S1: Perform global calibration of the workpiece coordinate system and robot coordinate system to obtain the initial surface error data of the optical element 4 to be processed. A machining path shared by two multi-degree-of-freedom robots is planned on the surface of optical element 4, based on the initial surface shape error data. The surface gradient is calculated, and then the cooperative feed rate of the two multi-degree-of-freedom robots is calculated based on the surface gradient. .

[0038] A laser tracker or online measuring probe is used to perform global calibration of the workpiece coordinate system and the coordinate systems of the two robots. An interferometer is used to measure the initial surface shape error data of optical element 4, and the central collaborative control module 7 plans a machining path shared by the first robot 1 and the second robot 2 on the surface of optical element 4 based on the initial surface shape error data.

[0039] In some embodiments, the processing path can be a grating processing path.

[0040] The aforementioned surface gradient is a derived quantity calculated from the initial surface error data, used to characterize the spatial rate of change of the surface error distribution of optical element 4. The modulus of the surface gradient... for: ; Central Coordination Control Module 7 based on the surface gradient model The inverse mapping yields the cooperative feed rate of the two multi-degree-of-freedom robots. for: ; in, The reference feed rate for the two multi-degree-of-freedom robots. This is a feed adjustment coefficient greater than zero. In regions with large surface gradients (i.e., steep changes in surface error), the cooperative feed rate... Reduce the feed rate to improve the correction resolution for material removal; in regions with flat surface gradients, increase the feed rate in conjunction with the material removal process. Increase the size to improve processing efficiency.

[0041] S2: Control the plasma tool head 5 to travel to the starting point of the machining path. The plasma tool head 5 excites the plasma jet with preset plasma process parameters and feeds at a coordinated speed. The optical element 4 is tangentially fed along the processing path to perform in-situ plasma activation treatment on its surface, forming an activation region.

[0042] The plasma tool head 5 is controlled to travel to the starting point of the machining path, and the gas supply unit is activated to provide protective gas. The plasma tool head 5 excites the plasma jet according to the preset plasma process parameters and feeds at a coordinated speed. Tangential feeding along the processing path: Taking the optical element 4 made of silicon carbide (SiC) material as an example, the high-energy plasma jet vertically bombards the SiC surface, thoroughly removing the microscopic organic contaminants in the later stage of processing, and breaking the chemical inert bonds on the SiC surface in situ, implanting a large number of polar groups such as hydroxyl (-OH), and performing plasma in-situ activation treatment on the surface of the optical element 4 to form an activation region. The surface free energy of the activation region achieves an order of magnitude jump, and the contact angle of the polishing slurry in this region instantly drops sharply from the initial hydrophobic state to the superhydrophilic state.

[0043] In some embodiments, plasma process parameters include the power and frequency of the plasma jet.

[0044] S3: Set the actual physical offset distance between the plasma tool head 5 and the polishing tool head 6 as follows. Its safe distance threshold is ,and satisfy ,in, For timeliness and safety factor and , The effective time window for activating the region; the time it takes for the polishing tool head 6 to travel to the same processing point of the plasma tool head 5 is defined as the time lag. Construct the time phase difference control equation: .

[0045] Actual physical offset distance It is determined by two constraints: its lower bound is the safe distance threshold to prevent collision between the moving ends of the first robot 1 and the second robot 2. Its upper limit is determined by the effective time window of the activation region. The decision was made to ensure the time lag. To satisfy the aforementioned time phase difference control equation, it is necessary to make .thus, The formula for calculating the value of is: ; in, ; Right now And must simultaneously satisfy Combining the results, we get: .

[0046] In some embodiments, in practical applications The value range is 0.1 to 0.2 to ensure that the polishing tool head 6 reaches the same processing point before the activation area significantly decays.

[0047] Based on physical experiments on the material properties of optical element 4, after in-situ plasma activation on the surface of optical element 4, its superhydrophilic state undergoes an effective time window for hydrophobic recovery from adsorbed impurities under natural conditions. Taking SiC material as an example, its effective time window Approximately 15 minutes, at the cooperative feed rate With what was taken The actual physical offset distance that satisfies both collision avoidance and time constraints can then be determined using the above formula. .

[0048] The central collaborative control module 7 treats the first robot 1 as the "leading phase" and the second robot 2 as the "lagging phase," monitoring in real time and ensuring that the temporal constraint boundary conditions of the time phase difference control equation are strictly met. This time phase difference control equation completely locks the absolute peak period of the activation state from a physical mechanism perspective, eliminating the risk of aging failure caused by traditional offline processing.

[0049] S4: Under the constraint and control of the time phase difference control equation, the polishing tool head 6 feeds at a cooperative feed rate. Upon reaching the activation area, polishing liquid is sprayed onto the area, forming a fluid film on the surface of the activation area. The polishing tool head 6 then polishes the fluid film area using preset polishing process parameters.

[0050] Under the constraint and control of the time phase difference control equation, the polishing tool head 6 operates at a cooperative feed rate. The device moves to the activation area on time and activates the polishing slurry supply unit to spray polishing slurry onto the surface of the optical element 4. In some embodiments, the polishing slurry is cerium oxide polishing slurry. The polishing slurry instantly spreads well on the surface of the optical element 4, forming a uniform and continuous fluid film area without any droplet slippage or local drying. The polishing tool head 6 polishes the fluid film area using preset polishing process parameters.

[0051] In some embodiments, the polishing process parameters include polishing speed and normal contact pressure.

[0052] This invention utilizes the central collaborative control module 7 to enforce the time phase difference control equation, ensuring that the polishing tool head 6 completes processing within the effective time window before the surface activity of the optical element 4 has significantly decreased. This fundamentally avoids the risk of aging failure under natural conditions and guarantees the process effect of plasma modification. At the same time, it also overcomes the problems of long process chains and secondary clamping errors caused by traditional single machine tools that can only perform a single task, which greatly shortens the manufacturing cycle of large-diameter or complex curved surface optical elements.

[0053] The in-situ activation and follow-up processing logic method provided in this invention is applicable to high-end manufacturing scenarios where the adhesion of processing fluid, lubricant, or coolant is difficult due to the hydrophobic inertness of the workpiece surface. This includes: in-situ activation before chemical mechanical planarization of large-size silicon wafers in the semiconductor manufacturing field; high-precision polishing and surface energy modification of titanium alloy artificial joints and biological implants in the biomedical field; and precision shaping processing of high-temperature alloy thin-walled parts and ceramic matrix composite blades in the aerospace structural parts field.

[0054] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0055] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A plasma in-situ activation and optical element polishing system, comprising two multi-degree-of-freedom robots and a workpiece stage; The workpiece stage is fixedly clamped with optical components to be processed; Its features are, The plasma in-situ activation and optical element polishing system also includes: a plasma tool head, a polishing tool head, and a central collaborative control module. The plasma tool head is fixedly mounted on the end effector of one of the multi-degree-of-freedom robots and is used to excite a plasma jet to perform in-situ plasma activation treatment on the surface of the optical element. The polishing tool head is fixedly mounted on the end effector of another multi-degree-of-freedom robot and is used to polish the surface of optical components after plasma in-situ activation treatment. The central collaborative control module is connected to the two multi-degree-of-freedom robots, the plasma tool head, and the polishing tool head respectively via an industrial communication bus, and performs unified collaborative control on the motion trajectory and motion sequence of the two multi-degree-of-freedom robots, as well as the process parameters of the plasma tool head and the polishing tool head. The polishing method based on the aforementioned plasma in-situ activation and optical element polishing system includes the following steps: S1: Perform global calibration of the workpiece coordinate system and robot coordinate system to obtain the initial surface shape error data of the optical element to be processed. Plan a processing path shared by two multi-degree-of-freedom robots on the surface of the optical element. Calculate the surface shape gradient based on the initial surface shape error data, and then calculate the cooperative feed speed of the two multi-degree-of-freedom robots based on the surface shape gradient. ; S2: Control the plasma tool head to travel to the starting point of the processing path. The plasma tool head excites a plasma jet with preset plasma process parameters and feeds at the cooperative feed rate. The optical element is tangentially fed along the processing path to perform in-situ plasma activation treatment on its surface, forming an activation region. S3: Set the actual physical offset distance between the plasma tool head and the polishing tool head as... Its safe distance threshold is ,and satisfy ,in, For timeliness and safety factor and , The effective time window for the activation region is defined as the time it takes for the polishing tool head to travel to the same processing point of the plasma tool head; the time lag is defined as the time it takes for the polishing tool head to travel to the same processing point of the plasma tool head. Construct the time phase difference control equation: ； S4: Under the constraint and control of the time phase difference control equation, the polishing tool head feeds at the cooperative feed rate. The tool head moves to the activation area and sprays polishing liquid onto the area, forming a fluid film area on the surface of the activation area. The polishing tool head then polishes the fluid film area using preset polishing process parameters.

2. The plasma in-situ activation and optical element polishing system according to claim 1, characterized in that, The plasma tool head integrates a gas supply unit, which provides protective gas while the plasma tool head generates a plasma jet.

3. The plasma in-situ activation and optical element polishing system according to claim 1 or 2, characterized in that, The plasma tool head is any one of an atmospheric pressure rotating plasma generator, a linear plasma array generator, a microwave plasma generator, or a dielectric barrier discharge plasma generator.

4. The plasma in-situ activation and optical element polishing system according to claim 1, characterized in that, The polishing tool head integrates a polishing fluid supply unit and a force sensor; The polishing fluid supply unit is used to supply polishing fluid; The force sensor is used to control the normal contact pressure of the polishing tool head.

5. The plasma in-situ activation and optical element polishing system according to claim 1 or 4, characterized in that, The polishing tool head is any one of bonded abrasive tools, flexible and semi-rigid tools, and special energy field-assisted tools. The bonded abrasive tool is any one of diamond grinding wheel, resin / metal bonded grinding head, and ball end mill; The flexible and semi-rigid tools are any one of abrasive belts, polishing belts, airbag polishing tools, and asphalt polishing discs. The special energy field auxiliary tool is either a magnetorheological polishing head or a liquid jet polishing head.

6. The plasma in-situ activation and optical element polishing system according to claim 1, characterized in that, The central collaborative control module includes a trajectory planning unit, a motion constraint control unit, and a process parameter control unit; The trajectory planning unit is used to plan the collaborative processing trajectory of the multi-degree-of-freedom robot; The motion constraint control unit is used to control the running trajectory and running sequence of the multi-degree-of-freedom robot; The process parameter control unit is used to control the plasma process parameters of the plasma tool head and the process parameters of the polishing tool head.

7. The plasma in-situ activation and optical element polishing system according to claim 1, characterized in that, The optical element has a surface shape that is any one of a plane, a sphere, an aspherical surface, or a freeform surface; the optical element is made of any one of silicon carbide, fused silica, K9 glass, microcrystalline glass, silicon single crystal, germanium single crystal, or calcium fluoride.

8. The plasma in-situ activation and optical element polishing system according to claim 1, characterized in that, The multi-degree-of-freedom robot can be any one of a multi-axis industrial robot or a multi-degree-of-freedom robotic arm, both of which possess multi-dimensional spatial motion capabilities.

9. The plasma in-situ activation and optical element polishing system according to claim 1, characterized in that, The plasma process parameters include the power and frequency of the plasma jet excitation; the polishing process parameters include the polishing rotation speed and normal contact pressure.

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