A method for manufacturing a single-crystal silicon complex curved surface weak rigid reflecting mirror

Abstract

The application provides a manufacturing method of a single-crystal silicon complex curved weak rigid reflector, which comprises the following steps: S1, using a diamond wire saw to rotate and cut a single-crystal silicon ingot to obtain an outer cylindrical surface of the reflector; S2, performing ultra-precision grinding on the cylindrical surface of the single-crystal silicon ingot; S3, using the diamond wire saw to rotate and cut to obtain the weak rigid reflector; S4, performing wet etching on the weak rigid reflector; S5, using a special fixture to clamp the reflector with low stress; S6, using an ultra-precision grinding method of a diamond grinding wheel to perform ultra-precision forming processing on the reflector; S7, using a gas bag polishing method or a solidified soft abrasive wheel grinding method to perform ultra-precision polishing on the reflector; and S8, using a magnetorheological polishing method or an ion beam processing method to perform ultra-precision shaping on the reflector, wherein the surface Ra is less than 0.5 nm, and the surface shape precision PV is less than 1 mu m. The application solves the problems of the existing manufacturing method, such as large reflector quality, complex manufacturing process and difficult-to-guarantee processing precision.

Description

Technical Field

[0001] The present invention relates to the technical field of reflector manufacturing, and in particular to a method for manufacturing a single-crystal silicon complex curved surface weak-rigidity reflector lens. Background Art

[0002] Deep space X-ray detection has important applications in many space technology fields such as positioning, navigation and timing systems, X-ray communications, and space science research, providing important support for national defense security, information communication, and the development of space science.

[0003] The deep space exploration X-ray telescope is a high-end optical equipment for deep space X-ray detection. The X-ray reflector is a key optical component of the deep space X-ray telescope, which is mainly used to reflect and converge low-density X-ray photons in space to achieve high-resolution imaging and high-sensitivity detection of space X-rays. In order to achieve total reflection and focusing of X-rays, the reflecting surface of the X-ray reflector is usually composed of two parts: a rotationally symmetric off-axis parabola and an off-axis hyperbola, and the reflecting surface is required to have both sub-nanometer roughness and sub-micron surface accuracy. In addition, in order to collect enough X-ray photons, the X-ray reflector requires ultra-thin wall thickness and multi-layer nesting to increase the effective light-collecting area of ​​the telescope. Therefore, the X-ray reflector has the characteristics of high surface accuracy, ultra-smooth surface processing requirements, and cylindrical thin walls and multi-layer nesting. It is a typical high-precision, high-surface quality, weak rigidity complex curved surface optical element, such as Figure 1 In summary, the complex surface shape, extremely high surface accuracy, thin wall and weak rigidity of X-ray reflectors pose severe challenges to the ultra-precision manufacturing process of reflectors.

[0004] Currently, the manufacturing methods of X-ray reflectors usually adopt the direct processing technology of microcrystalline glass and the electroforming nickel-cobalt replication technology.

[0005] like Figure 2 As shown in the figure, the direct processing of glass-ceramics involves directly trepanning the glass-ceramics, ultra-precision grinding of the inner and outer surfaces, polishing and shaping the inner surface, and coating the inner surface with an optical reflective film. Ultimately, a cylindrical single-layer X-ray reflector with high surface accuracy and an ultra-smooth surface is obtained. However, the direct processing of glass-ceramics is difficult to achieve for the direct forming of ultra-thin (<1mm) X-ray reflectors. Currently, the wall thickness of the processed X-ray reflectors is as high as 18mm, and the number of nested layers of the reflectors is only 4, which severely limits the effective light-collecting area of ​​the telescope.

[0006] like Figure 3As shown, the electroformed nickel-cobalt replication process first coats a separation film and an optical reflective film on the surface of a high-precision, ultra-smooth aluminum core mold. A 0.5-1mm thick nickel-cobalt alloy is then electroformed to form the reflector tube substrate. The optical reflective film and the nickel-cobalt alloy substrate are then separated from the aluminum core mold by rapid cooling, resulting in a cylindrical single-layer X-ray reflector. However, when manufacturing X-ray reflectors using the electroformed nickel-cobalt replication process, the stress distribution on the reflector surface easily changes during the electroforming and cooling demolding processes, causing deformation of the reflector and making it difficult to accurately guarantee the reflector's surface shape. Consequently, X-ray reflectors manufactured using the electroformed nickel-cobalt replication process exhibit poor surface shape accuracy, which directly affects the X-ray reflection path and telescope focusing performance.

[0007] In summary, the existing X-ray reflector manufacturing process still has the following problems:

[0008] 1. The density of the reflector base material is high, such as glass-ceramic (2.5g / cm 3 ), nickel-cobalt metal (8.9 g / cm 3 ), etc., the number of nested layers of lenses with the same quality is limited, which affects the light-gathering efficiency of the reflector.

[0009] 2. The direct processing technology of micro-ceramic glass is difficult to achieve ultra-thin-walled reflector processing in order to meet the rigidity requirements during grinding and polishing. As a result, the number of nested layers of reflectors is small (4 layers), and the effective light-collecting area of ​​the telescope is severely limited to only 0.08m 2 @1.0keV;

[0010] 3. During the cooling and demoulding process of the electroformed nickel replication process, it is easy to cause uneven stress distribution on the surface of the reflector, making it difficult to ensure surface accuracy and resulting in low angular resolution (>10");

[0011] 4. The electroforming nickel replication process is complex, the production cost of the master mold is high, and the waste electroplating solution will pollute the environment, which is not in line with the carbon neutral development concept;

[0012] To ensure sub-arcsecond focusing angle resolution and square-meter effective light-collecting area for next-generation X-ray telescopes, thin-walled cylindrical X-ray mirrors must simultaneously meet submillimeter wall thickness, submicron surface accuracy for complex curved surfaces (paraboloids and hyperboloids), and subnanometer reflective surface roughness. Therefore, innovation and breakthroughs in manufacturing X-ray mirrors with ultra-thin walls, high precision, high efficiency, and low cost are urgently needed. Summary of the Invention

[0013] In view of the technical problems existing in the existing manufacturing methods of X-ray reflectors, such as large mirror wall thickness, poor surface shape accuracy, and difficulty in controlling surface accuracy, the present invention provides a new method for manufacturing an X-ray reflector by annularly nesting and assembling weak rigidity complex curved reflective lenses. The method sequentially comprises "ultra-precision machining of weak rigidity single crystal silicon reflective lenses → annular assembly of multiple reflective lenses into a cylindrical single-layer reflective mirror → multi-layer nesting of cylindrical single-layer reflective mirrors into an X-ray reflector", such as Figure 4 As shown. Among them, the ultra-precision machining technology of thin-walled, weakly rigid single-crystal silicon reflective lenses is an important foundation for the method of the present invention to manufacture X-ray reflectors. To address the problem of ultra-precision machining of thin-walled, weakly rigid single-crystal silicon reflective lenses, the present invention also proposes an ultra-precision machining method for single-crystal silicon reflective lenses with complex curved surfaces, which sequentially adopts the following steps: "rotary cutting of the cylindrical surface of a single-crystal silicon ingot by a diamond wire saw → ultra-precision grinding of the cylindrical surface of a single-crystal silicon ingot → rotary cutting of the thin-walled, weakly rigid single-crystal silicon reflective lens by a diamond wire saw → wet etching of the weakly rigid reflective lens → low-stress clamping of the weakly rigid reflective lens → ultra-precision shaping and grinding of the complex curved surface of the reflective lens → ultra-precision polishing of the complex curved surface of the reflective lens → high-precision shaping of the weakly rigid reflective lens."

[0014] The multi-layer nested X-ray reflector is precisely assembled from multiple layers of ultra-thin reflectors with large curvature and complex surfaces. The processing requirements for each layer of reflectors are consistent. The present invention proposes a new method for manufacturing single-layer reflectors.

[0015] The technical means adopted in the present invention are as follows:

[0016] A method for manufacturing a single-crystal silicon complex curved surface weak rigidity reflective lens comprises the following steps:

[0017] S1: Use diamond wire saw rotary cutting method to process single crystal silicon ingot to obtain the outer cylindrical surface profile of the reflector;

[0018] S2: Based on the cylindrical surface shape of the reflector, ultra-precision forming processing is performed on the outer surface of the reflector using an arc diamond grinding wheel ultra-precision grinding method on a five-axis CNC machine tool;

[0019] S3: The single crystal silicon ingot processed in step S2 is processed by a diamond wire saw rotary cutting method to obtain the inner cylindrical surface profile of the reflector and complete the slicing of the thin-walled weak rigid reflector lens;

[0020] S4: Use HNA solution (also known as a mixed solution of acetic acid, hydrofluoric acid, and nitric acid) as the etching solution to wet-etch thin-walled, weakly rigid reflective lenses to eliminate damage caused by wire saw cutting and grinding wheel grinding processes;

[0021] S5: Using the outer surface of the thin-walled weak-rigid reflective lens as a reference, a special fixture is used to complete the low-stress clamping of the reflective lens;

[0022] S6: According to the free-form surface profile of the reflective mirror, the inner surface of the reflective mirror is super-precision formed on a five-axis numerical control machine tool by using a circular arc diamond grinding wheel super-precision grinding method;

[0023] S7: According to the free-form surface profile of the reflective mirror, the inner surface of the reflective mirror is super-precision formed on a five-axis numerical control machine tool by using a gas bag polishing or a fixed soft abrasive wheel grinding method;

[0024] S8: According to the free-form surface profile of the reflective mirror, the polished reflective mirror is high-precision shaped by using a magnetorheological polishing method or an ion beam polishing method;

[0025] Further, step S1 adopts a diamond wire saw rotary cutting method;

[0026] The rotary table of the wire cutting machine is placed on the guide rail of the workbench, so that the rotation and transverse feeding motion of the workpiece can be realized. The single crystal silicon ingot is fixed on the rotary table of the wire cutting machine. Numerical control programming is performed according to the profile information of the outer cylindrical surface of the reflective mirror, and is input into the wire cutting machine system. The rotary table is driven by the computer to rotate and feed the single crystal silicon ingot, so as to complete the cutting of the outer cylindrical surface of the single crystal silicon ingot. The sawing wire is cooperated with the motor, driving wheel, driven wheel and tensioning wheel to realize the circulation of the sawing wire and the tension control. The sawing wire is selected as the electroplated diamond sawing wire, the diameter of the sawing wire is 0.28-0.3mm, and the grit size of the electroplated abrasive on the surface of the sawing wire is 30-40μm. Under the working conditions of the sawing wire tension of 20-50N, the linear velocity of 2-5m / s, the feeding speed of 6.25-10μm / min and the cooling water flow of 10-20L / min, the diamond wire is used to cut the single crystal silicon ingot to obtain the outer cylindrical surface of the reflective mirror.

[0027] Further, step S2 adopts a circular arc diamond grinding wheel super-precision grinding method;

[0028] The single crystal silicon ingot processed by step S1 is fixed on a five-axis numerical control machine tool. Numerical control programming is performed according to the profile information of the outer surface of the reflective mirror, and the grinding track of the circular arc diamond grinding wheel is controlled to super-precision grind the outer surface.

[0029] The outer surface of the reflective mirror is processed by using a grinding wheel: the metal bond diamond grinding wheel used for grinding has a grit size distribution of W150-W10; the grinding wheel structure is a circular arc grinding wheel, and the diameter of the grinding wheel is Φ200mm; the grinding wheel is clamped on the spindle of the machine tool by a pneumatic clamp, the grinding wheel rotates at a speed of 6000-7000r / min, the grinding depth of each feeding is 15-30μm, the step increment is 0.6-0.8mm, the step speed is 50-65mm / min, and the profile error PV of the processed reflective mirror is less than 5μm, and the surface roughness Ra is less than 20nm;

[0030] Further, step S3 adopts a diamond wire saw rotary cutting method;

[0031] The turntable of the wire cutting machine is placed on the guide rail of the workbench to realize the rotation and lateral feeding of the workpiece. The single crystal silicon ingot processed in step S2 is fixed on the turntable of the wire cutting machine. According to the profile information of the cylindrical surface inside the reflective lens, CNC programming is performed and input into the wire cutting machine system. The turntable is controlled by the computer to drive the rotation and feeding movement of the single crystal silicon ingot to complete the cylindrical surface cutting of the single crystal silicon ingot. The saw wire is coordinated by the motor, the driving wheel, the driven wheel and the tension wheel to realize the circular wire feeding and tension control of the saw wire. Electroplated diamond saw wire is selected, the wire diameter is 0.28-0.3 mm, the abrasive grain size of the saw wire surface is 30-40 μm, and under the working conditions of a wire tension of 20-50 N, a linear speed of 2-5 m / s, a feed speed of 6.25-10 μm / min, and a cooling water flow rate of 10-20 L / min, the single crystal silicon ingot processed in step S2 is cut with the diamond wire to machine the inner cylindrical surface of the reflector, complete the slicing of the reflector lens, and obtain a thin-walled weak rigidity reflector lens;

[0032] Furthermore, step S4 adopts a wet etching method;

[0033] Using HNA solution as an etching solution, wherein the ratio of hydrofluoric acid (49%): nitric acid (70%): acetic acid (99.9%) is 1:5:4, the thin-walled weakly rigid reflective lens obtained after the treatment in step S3 is placed in the etching solution for 5 minutes for wet etching to eliminate damage caused by the wire saw cutting and grinding wheel grinding process;

[0034] Furthermore, in step S5, a special fixture is used to clamp the thin-walled weak-rigidity reflective lens;

[0035] Design the clamping surface of a special fixture according to the outer surface contour of the thin-walled weak-rigid reflective lens; place the special fixture on a constant temperature heating table and heat it to 70°C, and evenly apply a thin layer of paraffin wax on the entire clamping surface; place the reflective lens on the special fixture with the outer surface of the thin-walled weak-rigid reflective lens as a reference; turn off the constant temperature heating table and stop heating. Wait until the temperature cools to room temperature and the paraffin wax solidifies, and then the weak-rigid clamping of the thin-walled weak-rigid reflective lens is completed;

[0036] Furthermore, in step S6, an arc diamond wheel ultra-precision grinding method is used to perform ultra-precision forming processing on the inner surface of the reflective lens;

[0037] The reflective lens clamped by the special fixture is fixed on the five-axis CNC machine tool. According to the inner surface profile information of the reflective lens, CNC programming is performed to control the grinding trajectory of the arc diamond grinding wheel and perform ultra-precision grinding on the inner surface.

[0038] The inner surface of the reflector is machined using a grinding wheel: a metal-bonded diamond grinding wheel with a grain size distribution of W150 to W19 is used for rough grinding; the grinding wheel structure is a circular grinding wheel with a grinding wheel diameter of 200 mm; the grinding wheel is clamped on the machine tool spindle via a pneumatic fixture, the grinding wheel speed is 6000 to 9000 rpm, the grinding depth per feed is 20 to 30 μm, the step increment is 0.8 to 1.2 mm, and the step speed is 50 to 65 mm / min;

[0039] Semi-finishing and finishing grinding uses a resin-bonded diamond grinding wheel with a particle size distribution of W10 to W2.7. The grinding wheel is a circular arc grinding wheel with a diameter of 200 mm. The grinding wheel is clamped to the machine tool spindle via a pneumatic fixture, with a grinding wheel speed of 6000 to 9000 r / min, a grinding depth of 0.4 to 0.6 μm per feed, a step increment of 0.2 to 0.3 mm, and a step speed of 30 to 40 mm / min. The finished reflector has a profile error PV < 1 μm, a surface roughness Ra < 20 nm, and a lens thickness < 1 mm.

[0040] Furthermore, step S7 adopts an airbag polishing method;

[0041] In step S7-1, modeling and programming are performed based on the inner surface profile information of the reflector, and the model is input into the five-axis CNC machine tool system to control the polishing trajectory of the airbag;

[0042] In step S7-2, a polishing tool is assembled on a five-axis CNC machine tool. Driven by a motor, the spindle rotates, and the polishing tool moves along a predetermined path on the workpiece surface to polish the inner surface of the reflective lens. During operation, a polishing cloth is wrapped around the surface of the airbag and a retaining ring is placed to prevent deformation. An air pump, through a servo pressure regulating valve, fills the airbag with gas at a certain pressure to provide elasticity while ensuring sufficient contact pressure. The airbag spindle rotates a certain angle to prevent contact with the workpiece in the area where the rotation center speed is zero. The polishing tool's airbag is made of styrene-butadiene rubber (SBR). The airbag internal pressure is 0.1 MPa, the spindle speed is 1000-2000 r / min, the downward pressure is 0.8-1.2 mm, and the angle between the airbag spindle and the normal vector of the reflective lens is 18-22°. A polyurethane polishing pad is used as the film attached to the outside of the airbag. Silica sol is used as the polishing liquid. The resulting single-crystal silicon reflective lens has a surface roughness Ra <1 nm, a surface shape error PV <1 μm, and a lens thickness <1 mm.

[0043] Furthermore, step S7 adopts a chemical mechanical grinding method using a bonded soft abrasive grinding wheel;

[0044] In step S7-1, modeling and programming are performed in a five-axis CNC machine tool system according to the inner surface profile information of the reflector;

[0045] In step S7-2, the chemical mechanical grinding is performed using a fixed abrasive soft grinding wheel, and the soft grinding wheel with SiO2, CeO2 or MgO as abrasive material with an average particle size of 5 μm (#3000), phenolic resin and water-based polyurethane as binder, and sodium bicarbonate, zinc sulfate, calcium oxide and copper powder as additives is selected for grinding processing, and the grinding wheel is installed on a five-axis numerical control machine tool, the grinding wheel rotates at a speed of 1300-1800 r / min, the single axial feed amount is 1 μm, the transverse feed speed is 10 mm / min, and a single-crystal silicon mirror with a surface roughness Ra<1 nm, a surface shape error PV<1 μm and a mirror thickness <1 mm is obtained by processing;

[0046] Further, step S8 adopts the method of magnetorheological polishing;

[0047] In step S8-1, the inner surface profile information of the mirror is programmed and input into the magnetorheological polishing machine tool system to control the magnetorheological polishing track;

[0048] In step S8-2, the single-crystal silicon mirror processed in step S5 is clamped on the magnetorheological machine tool by a special clamp, the structure of the magnetic spherical polishing wheel adopted is a spherical surface with a diameter of 50-80 mm, the polishing wheel rotates at a speed of 200-280 r / min, the magnetorheological polishing liquid adopted has the following components: 0.5-0.8% of a surfactant, 0.5%-1.5% of a dispersing agent, 5-10% of cerium oxide or aluminum oxide or silicon carbide or diamond micro powder, 30-40% of carbonyl iron powder, and the rest is deionized water, the flow rate is 80-120 L / min, the magnetic field strength is 6-8 A, the pressure depth coefficient is 0.2-0.4, and a single-crystal silicon mirror with a surface roughness Ra<0.5 nm, a surface shape error PV<1 μm and a mirror thickness <1 mm is obtained by processing;

[0049] Further, step S8 adopts the method of ion beam polishing;

[0050] In step S8-1, the mirror processed in step S4 is cleaned by using O2 by the method of plasma cleaning to remove the abrasive material and impurities remaining on the surface of the mirror, the gas flow rate is 200 sccm, the excitation power is 400 W, and the cleaning time is 5 min;

[0051] In step S8-2, the plasma is excited by electrons emitted from a hot cathode filament, the base vacuum degree is 5×10 -4 Pa, the working gas is Ar gas (purity 99.999%), the gas flow rate is controlled by a gas flow meter, the working vacuum is maintained at 3.0×10 - 2 Pa, the ion beam energy is 1000 eV, and the beam current density is 265 μA·cm-2 The single-crystal silicon mirror piece is processed by using the ion beam figuring method with an acceleration voltage of 500eV and an ion beam incident angle of 5-85°, so that the single-crystal silicon mirror piece with a surface roughness of Ra<0.5nm, a surface shape error of PV<1μm and a thickness of <1mm is obtained.

[0052] Compared with the prior art, the present application has the following advantages:

[0053] 1. The base material has low density. The base material of the present application is single-crystal silicon (2.3g / cm 3 ), which has smaller density than microcrystalline glass (2.5g / cm 3 ) and metal nickel (8.9g / cm 3 ). Therefore, the weight of the mirror base can be greatly reduced, which is in line with the light-weight design concept of aerospace.

[0054] 2. The mirror has small single-layer wall thickness. The diamond wire cutting can cut a thin-wall mirror with a thickness of less than 1mm, so that more layers can be nested in a limited space, and the light-collecting area of the mirror is increased.

[0055] 3. The mirror has high surface precision. The process flow of the present application only needs single clamping, so that the influence of repeated clamping on the deformation of the mirror is reduced. In combination with the complex curved surface ultra-precision forming grinding technology and high-precision polishing shaping method, the weak rigid mirror has high surface shape precision and good surface quality, which can meet the use requirements of X-ray reflection focusing.

[0056] 4. The mirror piece ring assembly technology proposed in the present application solves the overall machining problem of the thin-wall cylindrical X-ray mirror, and can process the mirror locally and in segments, so that high-efficiency mass production is realized.

[0057] 5. The weak rigid mirror piece ultra-precision machining method proposed in the present application has simple process and low manufacturing cost. The single-crystal silicon ingot can be continuously cut for multiple times according to the surface shape of the first cutting, so that the machining efficiency is high, and the method is suitable for mass production with low cost.

[0058] Based on the above reasons, the present application can be widely popularized in the field of mirror manufacturing. BRIEF DESCRIPTION OF DRAWINGS

[0059] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0060] Figure 1 The schematic diagram of the multi-layer nested X-ray mirror is shown in the background art.

[0061] Figure 2 Schematic diagram of the direct processing technology of microcrystalline glass in background technology.

[0062] Figure 3 Schematic diagram of the electroforming nickel-cobalt replication process in the background technology.

[0063] Figure 4 This is a schematic diagram of the X-ray reflector assembled by annularly nested weak-rigidity complex curved reflective lenses described in the present invention.

[0064] Figure 5 This is a flow chart of the ultra-precision machining process for the single-crystal silicon complex curved surface weak-rigidity reflective lens of the present invention.

[0065] Figure 6 This is a schematic diagram of the ultra-precision processing method for the single-crystal silicon complex curved surface weak rigidity reflective lens according to the present invention. DETAILED DESCRIPTION

[0066] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0067] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0068] Example 1

[0069] like Figure 5 、 Figure 6 As shown, the present invention provides a method for manufacturing a single crystal silicon complex curved surface weak rigidity reflector, comprising the following steps:

[0070] S1: Use diamond wire saw rotary cutting method to process single crystal silicon ingot to obtain the outer cylindrical surface profile of the reflector;

[0071] S2: Based on the cylindrical surface shape of the reflector, ultra-precision forming processing is performed on the outer surface of the reflector using an arc diamond grinding wheel ultra-precision grinding method on a five-axis CNC machine tool;

[0072] S3: The single crystal silicon ingot processed in step S2 is processed by a diamond wire saw rotary cutting method to obtain the inner cylindrical surface profile of the reflector and complete the slicing of the thin-walled weak rigid reflector lens;

[0073] S4: Use HNA solution (also known as a mixed solution of acetic acid, hydrofluoric acid, and nitric acid) as the etching solution to wet-etch thin-walled, weakly rigid reflective lenses to eliminate damage caused by wire saw cutting and grinding wheel grinding processes;

[0074] S5: Using the outer surface of the thin-walled weak-rigid reflective lens as a reference, a special fixture is used to complete the low-stress clamping of the reflective lens;

[0075] S6: Based on the free-form surface of the reflective lens, ultra-precision forming processing is performed on the inner surface of the reflective lens using an arc diamond grinding wheel ultra-precision grinding method on a five-axis CNC machine tool;

[0076] S7: Based on the free-form surface of the reflector, the inner surface of the reflector is subjected to ultra-precision forming processing using the airbag polishing method on a five-axis CNC machine tool;

[0077] S8: Based on the free-form surface of the reflector, the polished reflector is subjected to high-precision shaping by using the magnetorheological polishing method;

[0078] Furthermore, step S1 includes: placing the turntable of the wire cutting machine on the guide rail of the workbench, that is, the rotation and lateral feed movement of the workpiece can be realized, fixing the single crystal silicon ingot on the turntable of the wire cutting machine, performing numerical control programming according to the contour information of the outer cylindrical surface of the reflector, inputting it into the wire cutting machine system, and driving the turntable to drive the single crystal silicon ingot to rotate and feed the motion through computer control to complete the cutting of the outer cylindrical surface of the single crystal silicon ingot. The saw wire is coordinated by the motor, the driving wheel, the driven wheel, and the tensioning wheel to realize the circular wire feeding and tension control of the saw wire. The saw wire is electroplated diamond saw wire with a saw wire diameter of 0.28 mm and a grit size of 30 to 40 μm on the surface of the saw wire. Under the working conditions of a saw wire tension of 20 N, a linear speed of 2 m / s, a feed speed of 6.25 μm / min, and a cooling water flow of 20 L / min, the single crystal silicon ingot is cut with diamond wire to obtain the outer cylindrical surface of the reflector;

[0079] Step S2 includes: fixing the single crystal silicon ingot processed in step S1 on a five-axis CNC machine tool, performing CNC programming according to the outer surface profile information of the reflector, controlling the grinding trajectory of the arc diamond grinding wheel, and performing ultra-precision grinding on the outer surface.

[0080] The ultra-precision grinding method using an arc diamond grinding wheel specifically includes using a grinding wheel to process the outer surface of the reflector: the metal bond diamond grinding wheel used for grinding has a particle size distribution of W150 to W10; the grinding wheel structure is an arc grinding wheel with a grinding wheel diameter of 200 mm; the grinding wheel is clamped on the machine tool spindle by a pneumatic clamp, the grinding wheel speed is 6000 to 7000 r / min, the grinding depth of each feed is 15 to 30 μm, the step increment is 0.6 to 0.8 mm, and the step speed is 50 to 65 mm / min. The surface error PV of the processed reflector is less than 5 μm, and the surface roughness Ra is less than 20 nm.

[0081] Step S3 includes: placing the turntable of the wire cutting machine on the guide rail of the workbench, that is, the rotation and lateral feed movement of the workpiece can be realized, the single crystal silicon ingot processed in step S2 is fixed on the turntable of the wire cutting machine, and the numerical control programming is performed according to the cylindrical surface profile information of the reflective lens, and input into the wire cutting machine system. The turntable is controlled by the computer to drive the rotation and feed movement of the single crystal silicon ingot to complete the cylindrical surface cutting of the single crystal silicon ingot. The saw wire is realized by the cooperation of the motor, the driving wheel, the driven wheel and the tensioning wheel. Circular wire feeding and tension control: electroplated diamond saw wire is used, the wire diameter is 0.28 mm, and the abrasive grain size of the saw wire surface is 30-40 μm. Under the working conditions of wire tension of 20 N, linear speed of 2 m / s, feed speed of 6.25 μm / min, and cooling water flow of 20 L / min, the single crystal silicon ingot processed in step S2 is cut with diamond wire to machine the inner cylindrical surface of the reflector, complete the slicing of the reflector lens, and obtain a thin-walled weak rigidity reflector lens;

[0082] Step S4 includes: using an HNA solution as an etching solution, wherein the ratio of hydrofluoric acid (49%): nitric acid (70%): acetic acid (99.9%) is 1:5:4, placing the thin-walled weakly rigid reflective lens obtained by the treatment in step S3 in the etching solution for 5 minutes to perform wet etching to eliminate damage caused by the wire saw cutting and grinding wheel grinding processes;

[0083] Step S5 includes: clamping the thin-walled weak-rigidity reflective lens using a special fixture;

[0084] Design the clamping surface of a special fixture according to the outer surface contour of the thin-walled weak-rigid reflective lens; place the special fixture on a constant temperature heating table and heat it to 70°C, and evenly apply a thin layer of paraffin wax on the entire clamping surface; place the reflective lens on the special fixture with the outer surface of the thin-walled weak-rigid reflective lens as a reference; turn off the constant temperature heating table and stop heating. Wait until the temperature cools to room temperature and the paraffin wax solidifies, and then the weak-rigid clamping of the thin-walled weak-rigid reflective lens is completed;

[0085] Furthermore, step S6 includes: fixing the reflective lens clamped by the special fixture on a five-axis CNC machine tool, performing CNC programming according to the inner surface profile information of the reflective mirror, controlling the grinding trajectory of the arc diamond grinding wheel, and performing ultra-precision grinding on the inner surface.

[0086] The arc diamond grinding wheel ultra-precision grinding method includes: using a grinding wheel to process the inner surface of the reflector, first using a metal bond diamond grinding wheel for rough grinding, and then using a resin bond diamond grinding wheel for semi-finishing and fine grinding to perform ultra-precision grinding:

[0087] The rough grinding uses a metal-bonded diamond grinding wheel with a particle size distribution of W150 to W19. The grinding wheel structure is a circular grinding wheel with a grinding wheel diameter of 200 mm. The grinding wheel is clamped on the machine tool spindle via a pneumatic clamp. The grinding wheel speed is 6000 to 9000 r / min, the grinding depth per feed is 20 to 30 μm, the step increment is 0.8 to 1.2 mm, and the step speed is 50 to 65 mm / min.

[0088] Semi-finishing and finishing grinding uses a resin-bonded diamond grinding wheel with a particle size distribution of W10 to W2.7. The grinding wheel is a circular arc grinding wheel with a diameter of 200 mm. The grinding wheel is clamped to the machine tool spindle via a pneumatic fixture, with a grinding wheel speed of 6000 to 9000 r / min, a grinding depth of 0.4 to 0.6 μm per feed, a step increment of 0.2 to 0.3 mm, and a step speed of 30 to 40 mm / min. The finished reflector has a profile error PV < 1 μm, a surface roughness Ra < 20 nm, and a lens thickness < 1 mm.

[0089] Furthermore, in step S7, the inner surface of the reflector is subjected to ultra-precision forming processing by using an airbag polishing method:

[0090] S7-1: Programming based on the inner surface profile of the reflector, inputting it into the five-axis CNC machine system to control the polishing trajectory of the airbag;

[0091] S7-2: On a five-axis CNC machine tool, the polishing tool is assembled. Driven by the motor, the spindle rotates, and the polishing tool moves along a predetermined path across the workpiece surface, polishing the inner surface of the reflective lens. During operation, a polishing cloth is wrapped around the surface of the airbag, and a retaining ring is placed to prevent deformation. An air pump, through a servo pressure regulating valve, fills the airbag with gas at a certain pressure, ensuring elasticity and sufficient contact pressure. The airbag spindle rotates a certain angle to prevent contact with the workpiece in the area where the center of rotation speed is zero. The polishing tool's airbag is made of styrene-butadiene rubber (SBR). The internal pressure is 0.1 MPa, the spindle speed is 1500 r / min, the downward pressure is 1 mm, and the angle between the airbag spindle and the normal vector of the reflective lens is 20°. A polyurethane polishing pad is used as the film on the outside of the airbag. Silica sol is used as the polishing liquid. The resulting single-crystal silicon reflective lens has a surface roughness Ra < 1 nm, a surface shape error PV < 1 μm, and a lens thickness < 1 mm.

[0092] Furthermore, step S8 uses magnetorheological polishing to perform mirror shaping:

[0093] A magnetic spherical polishing wheel and magnetorheological polishing fluid are used to polish the metallized lightweight reflector substrate. Under the action of a gradient magnetic field, the magnetic spherical polishing wheel is fully adhered and wrapped by the magnetorheological polishing fluid, forming a flexible polishing film. As the polishing wheel rotates and the magnetorheological polishing fluid flows, the flexible polishing film continuously contacts the substrate surface, achieving an ultra-smooth surface. The surface roughness of the processed lightweight reflector substrate is Ra < 0.5nm.

[0094] S8-1: Programming based on the inner surface profile information of the reflector, inputting it into the magnetorheological polishing machine system, and controlling the magnetorheological polishing trajectory;

[0095] S8-2: The single crystal silicon reflector processed in step S7 is clamped on a magnetorheological machine using a special fixture. The magnetic spherical polishing wheel used is a spherical surface with a diameter of 80 mm, and the polishing wheel speed is 200 r / min. The magnetorheological polishing fluid used contains the following components by volume: 0.5-0.8% surfactant, 0.5-1.5% dispersant, 5-10% cerium oxide or aluminum oxide or silicon carbide or diamond powder, 30-40% carbonyl iron powder, and the remainder is deionized water. The flow rate is 100 L / min, the magnetic field strength is 7A, and the pressure depth coefficient is 0.2. The single crystal silicon reflector lens with a surface roughness Ra of less than 0.5 nm, a surface error PV of less than 1 μm, and a lens thickness of less than 1 mm is obtained.

[0096] Example 2

[0097] S1: Use diamond wire saw rotary cutting method to process single crystal silicon ingot to obtain the outer cylindrical surface profile of the reflector;

[0098] S2: Based on the cylindrical surface shape of the reflector, ultra-precision forming processing is performed on the outer surface of the reflector using an arc diamond grinding wheel ultra-precision grinding method on a five-axis CNC machine tool;

[0099] S3: The single crystal silicon ingot processed in step S2 is processed by a diamond wire saw rotary cutting method to obtain the inner cylindrical surface profile of the reflector and complete the slicing of the thin-walled weak rigid reflector lens;

[0100] S4: Use HNA solution (also known as a mixed solution of acetic acid, hydrofluoric acid, and nitric acid) as the etching solution to wet-etch thin-walled, weakly rigid reflective lenses to eliminate damage caused by wire saw cutting and grinding wheel grinding processes;

[0101] S5: Using the outer surface of the thin-walled weak-rigid reflective lens as a reference, a special fixture is used to complete the low-stress clamping of the reflective lens;

[0102] S6: Based on the free-form surface of the reflective lens, ultra-precision forming processing is performed on the inner surface of the reflective lens using an arc diamond grinding wheel ultra-precision grinding method on a five-axis CNC machine tool;

[0103] S7: Based on the free-form surface of the reflector, the inner surface of the reflector is subjected to ultra-precision forming processing using a bonded soft abrasive grinding wheel on a five-axis CNC machine tool;

[0104] S8: Based on the free-form surface of the reflector, the polished reflector is subjected to high-precision shaping by using the ion beam polishing method;

[0105] Furthermore, step S1 includes: placing the turntable of the wire cutting machine on the guide rail of the workbench, that is, the rotation and lateral feed movement of the workpiece can be realized, fixing the single crystal silicon ingot on the turntable of the wire cutting machine, performing numerical control programming according to the contour information of the outer cylindrical surface of the reflector, inputting it into the wire cutting machine system, and driving the turntable to drive the single crystal silicon ingot to rotate and feed the motion through computer control to complete the cutting of the outer cylindrical surface of the single crystal silicon ingot. The saw wire is coordinated by the motor, the driving wheel, the driven wheel, and the tensioning wheel to realize the circular wire feeding and tension control of the saw wire. The saw wire is electroplated diamond saw wire with a saw wire diameter of 0.28 mm and a grit size of 30 to 40 μm on the surface of the saw wire. Under the working conditions of a saw wire tension of 20 N, a linear speed of 2 m / s, a feed speed of 6.25 μm / min, and a cooling water flow of 20 L / min, the single crystal silicon ingot is cut with diamond wire to obtain the outer cylindrical surface of the reflector;

[0106] Step S2 includes: fixing the single crystal silicon ingot processed in step S1 on a five-axis CNC machine tool, performing CNC programming according to the outer surface profile information of the reflector, controlling the grinding trajectory of the arc diamond grinding wheel, and performing ultra-precision grinding on the outer surface.

[0107] The ultra-precision grinding method using an arc diamond grinding wheel specifically includes using a grinding wheel to process the outer surface of the reflector: the metal bond diamond grinding wheel used for grinding has a particle size distribution of W150 to W10; the grinding wheel structure is an arc grinding wheel with a grinding wheel diameter of 200 mm; the grinding wheel is clamped on the machine tool spindle by a pneumatic clamp, the grinding wheel speed is 6000 to 7000 r / min, the grinding depth of each feed is 15 to 30 μm, the step increment is 0.6 to 0.8 mm, and the step speed is 50 to 65 mm / min. The surface error PV of the processed reflector is less than 5 μm, and the surface roughness Ra is less than 20 nm.

[0108] Step S3 includes: placing the turntable of the wire cutting machine on the guide rail of the workbench, that is, the rotation and lateral feed movement of the workpiece can be realized, the single crystal silicon ingot processed in step S2 is fixed on the turntable of the wire cutting machine, and the numerical control programming is performed according to the cylindrical surface profile information of the reflective lens, and input into the wire cutting machine system. The turntable is controlled by the computer to drive the rotation and feed movement of the single crystal silicon ingot to complete the cylindrical surface cutting of the single crystal silicon ingot. The saw wire is realized by the cooperation of the motor, the driving wheel, the driven wheel and the tensioning wheel. Circular wire feeding and tension control: electroplated diamond saw wire is used, the wire diameter is 0.28 mm, and the abrasive grain size of the saw wire surface is 30-40 μm. Under the working conditions of wire tension of 20 N, linear speed of 2 m / s, feed speed of 6.25 μm / min, and cooling water flow of 20 L / min, the single crystal silicon ingot processed in step S2 is cut with diamond wire to machine the inner cylindrical surface of the reflector, complete the slicing of the reflector lens, and obtain a thin-walled weak rigidity reflector lens;

[0109] Step S4 includes: using an HNA solution as an etching solution, wherein the ratio of hydrofluoric acid (49%): nitric acid (70%): acetic acid (99.9%) is 1:5:4, placing the thin-walled weakly rigid reflective lens obtained by the treatment in step S3 in the etching solution for 5 minutes to perform wet etching to eliminate damage caused by the wire saw cutting and grinding wheel grinding processes;

[0110] Step S5 includes: clamping the thin-walled weak-rigidity reflective lens using a special fixture;

[0111] Design the clamping surface of a special fixture according to the outer surface contour of the thin-walled weak-rigid reflective lens; place the special fixture on a constant temperature heating table and heat it to 70°C, and evenly apply a thin layer of paraffin wax on the entire clamping surface; place the reflective lens on the special fixture with the outer surface of the thin-walled weak-rigid reflective lens as a reference; turn off the constant temperature heating table and stop heating. Wait until the temperature cools to room temperature and the paraffin wax solidifies, and then the weak-rigid clamping of the thin-walled weak-rigid reflective lens is completed;

[0112] Furthermore, step S6 includes: fixing the reflective lens clamped by the special fixture on a five-axis CNC machine tool, performing CNC programming according to the inner surface profile information of the reflective mirror, controlling the grinding trajectory of the arc diamond grinding wheel, and performing ultra-precision grinding on the inner surface.

[0113] The arc diamond grinding wheel ultra-precision grinding method includes: using a grinding wheel to process the inner surface of the reflector, first using a metal bond diamond grinding wheel for rough grinding, and then using a resin bond diamond grinding wheel for semi-finishing and fine grinding to perform ultra-precision grinding:

[0114] The rough grinding uses a metal-bonded diamond grinding wheel with a particle size distribution of W150 to W19. The grinding wheel structure is a circular grinding wheel with a grinding wheel diameter of 200 mm. The grinding wheel is clamped on the machine tool spindle via a pneumatic clamp. The grinding wheel speed is 6000 to 9000 r / min, the grinding depth per feed is 20 to 30 μm, the step increment is 0.8 to 1.2 mm, and the step speed is 50 to 65 mm / min.

[0115] Semi-finishing and finishing grinding uses a resin-bonded diamond grinding wheel with a particle size distribution of W10 to W2.7. The grinding wheel is a circular arc grinding wheel with a diameter of 200 mm. The grinding wheel is clamped to the machine tool spindle via a pneumatic fixture, with a grinding wheel speed of 6000 to 9000 r / min, a grinding depth of 0.4 to 0.6 μm per feed, a step increment of 0.2 to 0.3 mm, and a step speed of 30 to 40 mm / min. The finished reflector has a profile error PV < 1 μm, a surface roughness Ra < 20 nm, and a lens thickness < 1 mm.

[0116] Furthermore, in step S7, the inner surface of the reflector is subjected to ultra-precision forming processing by using a fixed soft abrasive grinding wheel grinding method:

[0117] S7-1: In a five-axis CNC machine tool system, programming is performed based on the inner surface profile information of the reflector;

[0118] S7-2: Chemical mechanical grinding using a bonded soft abrasive grinding wheel, using SiO2, CeO2, or MgO with an average particle size of 5 μm (#3000) as the abrasive, phenolic resin or water-based polyurethane as the binder, and sodium bicarbonate, zinc sulfate, calcium oxide, and copper powder as additives. The grinding wheel is mounted on a five-axis CNC machine tool at a grinding wheel speed of 1500 r / min, a single axial feed of 1 μm, and a transverse feed rate of 10 mm / min. A single-crystal silicon reflective lens with a surface roughness Ra <1 nm, a surface form error PV <1 μm, and a lens thickness <1 mm is obtained.

[0119] Furthermore, step S8 uses ion beam polishing to perform reflector shaping:

[0120] The light-weight reflector substrate that has been metallized is polished by ion beam bombardment to achieve an ultra-smooth surface.

[0121] S8-1: Using a plasma cleaning method, use O2 to clean the reflective mirror that has been ground in step S4 to remove the abrasive and impurities remaining on the surface of the reflective mirror. The gas flow rate is 200 seem, the excitation power is 400 W, and the cleaning time is 5 minutes.

[0122] S8-2: The plasma is excited by electrons emitted by the hot cathode filament, and the background vacuum is 5×10 -4 Pa, the working gas is Ar gas (purity 99.999%), the filling flow is controlled by a gas flow meter, and the working vacuum is maintained at 3.0×10 -2 Pa, ion beam energy 1000 eV, beam current density 265 μA·cm -2 , accelerating voltage 500eV, ion beam incident angle 5°~85°;

[0123] The use of an online topography measurement system can provide real-time feedback on the surface topography characteristics, identify high-point areas, and control the bombardment position and dwell time of the high-energy ion beam, thereby achieving precise removal of specific high-point areas on the substrate metallized surface and achieving ultra-smooth surface polishing. The resulting single-crystal silicon reflective lens has a surface roughness Ra < 0.5nm, a surface shape error PV < 1μm, and a lens thickness < 1mm.

[0124] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for manufacturing a single-crystal silicon complex curved surface weak rigidity reflective lens, characterized in that: The following steps are involved: S1: Use diamond wire saw rotary cutting method to process single crystal silicon ingot to obtain the outer cylindrical surface profile of the reflector; S2: Based on the cylindrical surface shape of the reflector, ultra-precision forming processing is performed on the outer surface of the reflector using an arc diamond grinding wheel ultra-precision grinding method on a five-axis CNC machine tool; S3: The single crystal silicon ingot processed in step S2 is processed by a diamond wire saw rotary cutting method to obtain the inner cylindrical surface profile of the reflector and complete the slicing of the thin-walled weak rigid reflector lens; S4: Wet etching of thin-walled, weakly rigid reflective lenses using an etching solution to eliminate damage caused by wire saw cutting and wheel grinding. S5: Using the outer surface of the thin-walled weak-rigid reflective lens as a reference, a special fixture is used to complete low-stress clamping of the reflective lens; specifically, the clamping surface of the special fixture is designed according to the outer surface contour of the thin-walled weak-rigid reflective lens; the special fixture is placed on a constant temperature heating table for heating to 70°C, and a layer of paraffin wax is evenly applied to the entire clamping surface; using the outer surface of the thin-walled weak-rigid reflective lens as a reference, the reflective lens is placed on the special fixture; the constant temperature heating table is turned off, heating is stopped, and the temperature is cooled to room temperature. After the paraffin wax solidifies, the weak-rigid clamping of the thin-walled weak-rigid reflective lens is completed; S6: Based on the free-form surface of the reflective lens, ultra-precision forming processing is performed on the inner surface of the reflective lens using an arc diamond grinding wheel ultra-precision grinding method on a five-axis CNC machine tool; S7: Based on the free-form surface of the reflector, the inner surface of the reflector is ultra-precision polished using airbag polishing or bonded soft abrasive grinding wheel grinding on a five-axis CNC machine tool; S8: Based on the free-form surface shape of the reflector, the polished reflector is subjected to high-precision shaping processing by using a magnetorheological polishing method or an ion beam polishing method.

2. The method for manufacturing a single crystal silicon complex curved surface weak rigidity reflective lens according to claim 1, characterized in that: Step S1 adopts a diamond wire saw rotary cutting method, which specifically includes the following steps: By placing the turntable of the wire cutting machine on the guide rail of the workbench, the rotation and lateral feed movement of the workpiece can be realized. The single crystal silicon ingot is fixed on the turntable of the wire cutting machine, and the contour information of the outer cylindrical surface of the reflector is input into the wire cutting machine system. The turntable is controlled by a computer to drive the rotation and feed movement of the single crystal silicon ingot to complete the cutting of the outer cylindrical surface of the single crystal silicon ingot. The saw wire is electroplated diamond saw wire with a saw wire diameter of 0.28~0.3mm and abrasive grain size of 30~40μm on the saw wire surface. Under the working conditions of saw wire tension of 20~50N, linear speed of 2~5m / s, feed speed of 6.25~10μm / min, and cooling water flow of 10~20L / min, the single crystal silicon ingot is cut with diamond wire to obtain the outer cylindrical surface of the reflector lens.

3. The method for manufacturing a single crystal silicon complex curved surface weak rigidity reflective lens according to claim 1, characterized in that: Step S2 adopts the arc diamond grinding wheel ultra-precision grinding method, which specifically includes the following steps: The single crystal silicon ingot processed in step S1 is fixed on a five-axis CNC machine tool, and the outer surface profile information of the reflector is input into the control system to control the grinding trajectory of the arc diamond grinding wheel to perform ultra-precision grinding on the outer surface; The outer surface of the reflector is processed by a grinding wheel: a metal-bonded diamond grinding wheel with a particle size distribution of W150~W10 is used for grinding; the grinding wheel structure is an arc grinding wheel with a grinding wheel diameter of Φ200mm; the grinding wheel is clamped on the machine tool spindle by a pneumatic clamp, the grinding wheel speed is 6000~7000r / min, the grinding depth of each feed is 15~30μm, the step increment is 0.6~0.8mm, the step speed is 50~65mm / min, the contour surface error PV of the processed reflector is <5μm, and the surface roughness Ra is <20nm.

4. The method for manufacturing a single crystal silicon complex curved surface weak rigidity reflective lens according to claim 1, characterized in that: Step S3 uses a diamond wire saw rotary cutting method, which specifically includes the following steps: The turntable of the wire cutting machine is placed on the guide rail of the workbench to realize the rotation and lateral feed movement of the workpiece. The single crystal silicon ingot processed in step S2 is fixed on the turntable of the wire cutting machine, and the contour information of the inner cylindrical surface of the reflective lens is input into the wire cutting machine system. The turntable is controlled by a computer to drive the rotation and feed movement of the single crystal silicon ingot to complete the cylindrical surface cutting of the single crystal silicon ingot. The saw wire is electroplated diamond saw wire with a saw wire diameter of 0.28~0.3mm and an abrasive grain size of 30~40μm on the saw wire surface. Under the working conditions of saw wire tension of 20~50N, linear speed of 2~5m / s, feed speed of 6.25~10μm / min, and cooling water flow of 10~20L / min, the single crystal silicon ingot processed in step S2 is cut with diamond wire to process the inner cylindrical surface of the reflective mirror, complete the slicing of the reflective lens, and obtain a thin-walled weak rigidity reflective lens.

5. The method for manufacturing a single crystal silicon complex curved surface weak rigidity reflective lens according to claim 1, characterized in that: Step S4 specifically includes the following steps: An HNA solution is used as an etching solution, wherein the ratio of hydrofluoric acid: nitric acid: acetic acid is 1:5:

4. The thin-walled weakly rigid reflective lens obtained by the treatment in step S3 is placed in the etching solution for wet etching.

6. The method for manufacturing a single crystal silicon complex curved surface weak rigidity reflective lens according to claim 1, characterized in that: Step S6 uses an arc diamond wheel ultra-precision grinding method to perform ultra-precision forming processing on the inner surface of the reflective lens, which specifically includes the following steps: The reflective lens clamped by a special fixture is fixed on a five-axis CNC machine tool. The inner surface profile information of the reflective mirror is input into the control system to control the grinding trajectory of the arc diamond grinding wheel and perform ultra-precision grinding on the inner surface. The inner surface of the reflector is machined using a grinding wheel: a metal-bonded diamond grinding wheel with a grain size distribution of W150 to W19 is used for rough grinding. The grinding wheel structure is a circular grinding wheel with a grinding wheel diameter of 200 mm. The grinding wheel is clamped on the machine tool spindle via a pneumatic clamp. The grinding wheel speed is 6000 to 9000 rpm, the grinding depth per feed is 20 to 30 μm, the step increment is 0.8 to 1.2 mm, and the step speed is 50 to 65 mm / min. Semi-finishing and finishing grinding use resin-bonded diamond grinding wheels with a particle size distribution of W10 to W2.

7. The grinding wheel structure is a circular arc grinding wheel with a grinding wheel diameter of Φ200mm. The grinding wheel is clamped on the machine tool spindle via a pneumatic fixture, with a grinding wheel speed of 6000-9000r / min, a grinding depth of 0.4-0.6μm per feed, a step increment of 0.2-0.3mm, and a step speed of 30-40mm / min. The processed reflector profile surface error PV<1μm, the surface roughness Ra<20nm, and the lens thickness<1mm.

7. The method for manufacturing a single crystal silicon complex curved surface weak rigidity reflective lens according to claim 1, characterized in that: Step S7 uses airbag polishing, which specifically includes the following steps: S7-1: Input the inner surface profile information of the reflector into the five-axis CNC machine system to control the polishing trajectory of the airbag; S7-2: On a five-axis CNC machine tool, the polishing tool is assembled. Driven by the motor, the spindle rotates, and the polishing tool moves along a predetermined route on the workpiece surface to polish the inner surface of the reflective lens. During operation, a polishing cloth is used to wrap the surface of the airbag and a fixed ring is put on to prevent the airbag from deforming. The air pump fills the airbag with gas at a certain pressure through a servo pressure regulating valve to give the airbag a certain elasticity while ensuring sufficient contact pressure. The airbag spindle rotates a certain angle to avoid contact with the workpiece in the area where the rotation center speed is zero. The airbag material of the polishing tool is styrene-butadiene rubber, the internal pressure of the airbag is 0.1MPa, the spindle speed is 1000-2000r / min, the downward pressure is 0.8-1.2mm, the angle between the airbag spindle and the normal vector of the reflector is 18-22°, the film on the outside of the airbag is made of a polyurethane polishing pad, and silica sol is used as the polishing liquid. The surface roughness Ra <1nm, the surface shape error PV <1μm, and the lens thickness <1mm are obtained by processing.

8. The method for manufacturing a single crystal silicon complex curved surface weak rigidity reflective lens according to claim 1, characterized in that: Step S7 adopts a fixed soft abrasive grinding wheel grinding method, comprising the following steps: S7-1: Input the inner surface profile information of the reflector into the five-axis CNC machine tool system; S7-2: Use a bonded soft abrasive grinding wheel for chemical mechanical grinding. Select SiO2, CeO2 or MgO with an average particle size of 5μm as abrasive, phenolic resin, water-based polyurethane as binder, sodium bicarbonate, zinc sulfate, calcium oxide and copper powder as additives. The grinding process is carried out using a soft abrasive grinding wheel with the following mass proportions: 20% abrasive, 15% phenolic resin, 10% sodium bicarbonate, 15% zinc sulfate, 5% calcium oxide, and the rest copper powder. The grinding wheel is installed on a five-axis CNC machine tool with a grinding wheel speed of 1300~1800r / min, a single axial feed of 1μm, and a lateral feed speed of 10mm / min. The processed single-crystal silicon reflective lens has a surface roughness Ra <1nm, a surface shape error PV <1μm, and a lens thickness <1mm.

9. The method for manufacturing a single crystal silicon complex curved surface weak rigidity reflective lens according to claim 1, characterized in that: Step S8 adopts a magnetorheological polishing method, which specifically includes the following steps: S8-1: Input the inner surface profile information of the reflector into the magnetorheological polishing machine system to control the magnetorheological polishing trajectory; S8-2: The single crystal silicon reflector processed in step S5 is clamped on a magnetorheological machine by a special fixture. The structure of the magnetic spherical polishing wheel used is a sphere with a diameter of 50~80mm, and the polishing wheel speed is 200~280r / min; the volume percentage of each component of the magnetorheological polishing fluid used is: 0.5~0.8% surfactant, 0.5%~1.5% dispersant, 5~10% cerium oxide or aluminum oxide or silicon carbide or diamond powder, 30~40% carbonyl iron powder, and the rest is deionized water; the flow rate is 80~120L / min, the magnetic field strength is 6~8A, and the pressure depth coefficient is 0.2~0.

4. The surface roughness Ra is less than 0.5nm, the surface shape error PV is less than 1μm, and the lens thickness is less than 1mm.

10. The method for manufacturing a single crystal silicon complex curved surface weak rigidity reflective lens according to claim 1, characterized in that: Step S8 uses an ion beam polishing method, which specifically includes the following steps: S8-1: Using plasma cleaning, use O2 to clean the reflective mirror that has been ground in step S4 to remove the abrasive and impurities remaining on the surface of the reflective mirror. The gas flow rate is 200 sccm, the excitation power is 400 W, and the cleaning time is 5 minutes. S8-2: The plasma is excited by electrons emitted from the hot cathode filament, and the background vacuum is 5×10 -4 Pa, the working gas is Ar gas, the filling flow is controlled by a gas flow meter, and the working vacuum is maintained at 3.0×10 -2 Pa, ion beam energy 1000 eV, beam current density 265 μA·cm -2 , acceleration voltage 500eV, ion beam incident angle 5°~85°, processing to obtain single crystal silicon reflective lens with surface roughness Ra<0.5nm, surface shape error PV<1μm, and lens thickness<1mm.

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