A polishing device and a polishing method for an ultra-precise special-shaped lightweight mirror

Abstract

The application provides a polishing device and polishing method for an ultra-precise special-shaped light reflector, and relates to the technical field of polishing, to solve the technical problems of high cost and low processing efficiency of the polishing equipment. The method comprises the following steps: providing a reflector, the reflector comprising a triangular prism-shaped base body and a plane glass, the cross section of the base body is in the shape of an isosceles right triangle, and the plane glass is formed on the hypotenuse side of the base body; performing rough polishing on the plane glass of the reflector; placing the reflector after rough polishing in a ring polishing device, and performing fine surface shape correction on the plane glass under preset conditions; detecting whether the surface shape of the fine-corrected plane glass reaches a preset aperture, and if not, adjusting the pitch asphalt mode of the ring polishing device until the surface shape of the plane glass reaches the preset aperture. The method has low equipment cost and can be mass-produced, and has high processing efficiency.

Description

Technical Field

[0001] This invention relates to the field of polishing technology, and in particular to a polishing device and method for an ultra-precision irregularly shaped lightweight reflector. Background Technology

[0002] A layer of glass is sintered onto the surface of a titanium alloy substrate. This glass is then polished and vacuum-deposited with a reflective coating to form a lightweight mirror with high surface shape and reflectivity. The titanium alloy substrate in this lightweight mirror provides structural support. Due to its lightweight, high power density, and good thermal stability, this lightweight mirror is used in various applications.

[0003] In related technologies, magnetorheological or ion beam polishing techniques are used to process ultra-precision lightweight mirrors, but the equipment is expensive and the processing efficiency is low. Summary of the Invention

[0004] The purpose of this invention is to provide a polishing device and method for ultra-precision irregular-shaped lightweight mirrors, so as to solve the technical problems of high cost and low processing efficiency of ultra-precision irregular-shaped lightweight mirror polishing equipment.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] In a first aspect, the present invention provides a polishing method for an ultra-precision irregularly shaped lightweight reflector, comprising:

[0007] A reflector is provided, the reflector comprising a triangular prism-shaped substrate and a flat glass, the cross-section of the substrate being an isosceles right triangle, and the flat glass being formed on the hypotenuse side of the substrate;

[0008] The planar glass of the reflector is subjected to rough polishing;

[0009] The rough-polished mirror is placed in a ring polishing device, and the surface shape of the flat glass is refined under preset conditions;

[0010] The surface shape of the refined flat glass is checked to see if it reaches the preset aperture. If not, the asphalt mold of the ring polishing device is adjusted until the surface shape of the flat glass reaches the preset aperture.

[0011] According to at least one embodiment of the present invention, the preset aperture ranges from -0.2 to +0.2.

[0012] According to at least one embodiment of the present invention, the substrate is made of titanium or a titanium alloy; and / or,

[0013] The flat glass is K9 optical glass.

[0014] According to at least one embodiment of the present invention, the ring polishing device includes a rotatable asphalt mold, a dressing disc, and a self-rotating workpiece ring, wherein the dressing disc is slidably disposed on the asphalt mold along the radial direction of the asphalt mold; the step of placing the rough-polished mirror in the ring polishing device includes:

[0015] The reflector is placed in the workpiece groove of the circular plate, and the circular plate is placed inside the workpiece ring. Under the rotation and swing of the workpiece ring, the circular plate drives the reflector to refine the surface shape on the asphalt mold.

[0016] According to at least one embodiment of the present invention, the preset conditions include: the rotational speed of the asphalt mold is in the range of 2 r / min to 2.5 r / min.

[0017] According to at least one embodiment of the present invention, the preset conditions further include: the material of the asphalt mold is a mixture of 60# asphalt and 65# asphalt in a weight ratio of 1:4, and the softening point of the asphalt mold is 64°C.

[0018] According to at least one embodiment of the present invention, the ambient temperature of the asphalt mold is in the range of 22℃ to 24℃, and the temperature gradient is less than 1℃ / h.

[0019] According to at least one embodiment of the present invention, the step of placing the rough-polished mirror in the ring polishing apparatus further includes:

[0020] The polishing liquid is placed on the asphalt mold. The polishing liquid includes cerium oxide or ferric oxide, and the flow rate of the polishing liquid ranges from 0.8 l / h to 1.0 l / h.

[0021] According to at least one embodiment of the present invention, the step of adjusting the asphalt mold of the ring polisher until the surface shape of the flat glass reaches the preset aperture includes:

[0022] When the surface shape of the flat glass is smaller than the preset aperture, the trimming disc moves radially toward the center of the asphalt mold to press and trim the part of the asphalt mold near the center.

[0023] When the surface shape of the flat glass is larger than the preset aperture, the trimming disc moves radially away from the center of the asphalt mold to trim the area near the edge of the asphalt mold.

[0024] According to at least one embodiment of the present invention, detecting whether the surface shape of the refined planar glass reaches a preset aperture includes:

[0025] The reflector, interferometer lens, and auxiliary measurement platform are left to stand in the measurement room for more than 2 hours. When the ambient temperature of the measurement room is T℃, the measured aperture value is [y1, y2], and the surface shape of the plane glass reaches the preset aperture. Wherein, y1=-0.25T+5.3, y2=-0.25T+5.7, 20℃≤T≤24℃.

[0026] Secondly, the present invention also provides a polishing apparatus for an ultra-precision irregularly shaped lightweight reflector, for performing the polishing method described in the first aspect, the polishing apparatus comprising a ring polishing device for polishing the reflector, and a fixture for fixing the reflector.

[0027] According to at least one embodiment of the present invention, the tooling includes a circular plate that matches the workpiece ring, the circular plate having a workpiece groove for mounting the reflector, and the circular plate being made of polytetrafluoroethylene.

[0028] According to at least one embodiment of the present invention, the tooling further includes four auxiliary blocks, each with a right-angled trapezoidal cross-section, and is respectively disposed at the four corners of the substrate near the flat glass. The auxiliary blocks are bonded to the isosceles side surfaces of the substrate, with the right-angled side surfaces of the auxiliary blocks perpendicular to the flat glass. The distance between the right-angled side surfaces of two opposite auxiliary blocks is greater than the width of the flat glass. The distance between the bottom surface of the auxiliary block and the side edge of the substrate away from the flat glass is less than the distance between the flat glass and the side edge of the substrate away from the flat glass.

[0029] According to at least one embodiment of the present invention, the distance between the far-away end faces of two auxiliary blocks located on the same right-angled side is greater than the length of the flat glass.

[0030] According to at least one embodiment of the present invention, the auxiliary block is made of K9 optical glass.

[0031] According to at least one embodiment of the present invention, 1001 type optical adhesive is used between the auxiliary block and the substrate, and the area of ​​the optical adhesive on each auxiliary block is 3% to 4% of the area of ​​the right-angled side surface.

[0032] In one or more technical solutions provided in the exemplary embodiments of the present invention, at least one of the following beneficial effects can be achieved.

[0033] In the polishing method of the ultra-precision irregularly shaped lightweight reflector of the exemplary embodiment of the present invention, the reflector includes a triangular prism-shaped substrate and a flat glass. The cross-sectional shape of the substrate is an isosceles right triangle, and the flat glass is formed on the hypotenuse of the substrate. The substrate typically provides support for the flat glass and can be installed in a corresponding system. To obtain high reflectivity and resolution of the reflector, the reflector, i.e., the flat glass portion, needs to be polished and finished. First, the flat glass formed on the substrate is rough-polished. Then, the surface shape of the rough-polished flat glass is refined under preset conditions using a ring polishing device. The refined flat glass is inspected to determine whether it reaches the preset aperture. If it does not meet the standard requirements, the surface shape of the flat glass is refined again after adjusting the asphalt mold of the ring polishing device until the preset aperture is reached. Compared with the prior art using magnetorheological or ion beam polishing technology, the polishing of the ultra-precision irregularly shaped lightweight reflector in the ring polishing device of the exemplary embodiment of this application can achieve the standard aperture value, and the equipment cost is low, allowing for mass production and high processing efficiency.

[0034] Furthermore, during the inspection of the refined surface of the flat glass to determine whether it meets the preset aperture, the surface shape measurement of the ultra-precision reflector varies greatly with the ambient temperature. The surface shape measurement of the entire batch of ultra-precision reflectors cannot be completely accurate under the same temperature conditions, resulting in the polished reflector surface shape failing to meet standard requirements. The ultra-precision irregular-shaped lightweight reflector surface shape measurement of this exemplary embodiment of the invention, based on the influence of different temperatures on the surface shape, can calibrate the reflector surface shape detection under temperature fluctuations during surface shape inspection to make it equivalent to the surface shape value under the same temperature conditions. This ensures that the surface shape of the same batch of ultra-precision irregular-shaped lightweight reflectors meets the acceptance standard requirements. Attached Figure Description

[0035] The accompanying drawings illustrate exemplary embodiments of the invention and, together with the description thereof, serve to explain the principles of the invention. These drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification.

[0036] Figure 1 This is a side view schematic diagram of the reflector structure according to an embodiment of the present invention;

[0037] Figure 2 yes Figure 1 A schematic diagram of the AA cross-sectional structure;

[0038] Figure 3 This is a front view schematic diagram of the reflector (auxiliary block) according to an embodiment of the present invention;

[0039] Figure 4 This is a top view of the reflector (auxiliary block) according to an embodiment of the present invention;

[0040] Figure 5A This is a bottom view structural diagram of a physical reflector (auxiliary block) according to an embodiment of the present invention;

[0041] Figure 5B This is a top view of the actual structure of a reflector (auxiliary block) according to an embodiment of the present invention;

[0042] Figure 5C This is a front view structural schematic diagram of a reflector (auxiliary block) according to an embodiment of the present invention;

[0043] Figure 6 This is a top view of the ring-throwing device according to an embodiment of the present invention;

[0044] Figure 7 It is a scattering diagram of the surface shape changing with temperature according to an embodiment of the present invention.

[0045] Figure label:

[0046] 10. Matrix; 11. Isosceles lateral surface;

[0047] 20. Flat glass;

[0048] 30. Auxiliary block; 31. Bottom surface; 32. Right-angled side surface;

[0049] 41. Asphalt mold; 42. Workpiece ring; 43. Circular plate; 44. Clamp. Detailed Implementation

[0050] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0051] The fabrication of ultra-precision irregularly shaped lightweight mirrors requires a reflectivity of over 95% in the visible light range, a mirror resolution of 1.4″ (measured within a φ100 range), and a distance of 4000 meters from infinity. These ultra-precision irregularly shaped lightweight mirrors are commonly used in aerospace optoelectronic pods, satellites, high-altitude reconnaissance cameras, ships, and drones. Current methods for fabricating ultra-precision irregularly shaped lightweight mirrors employ magnetorheological or ion beam polishing techniques, which involve expensive equipment and relatively low processing efficiency.

[0052] To address the aforementioned issues, the exemplary embodiment of this invention provides a polishing method for ultra-precision irregularly shaped lightweight reflectors. This method employs a ring polishing device and considers the impact of ambient temperature fluctuations on the results during surface shape inspection, thereby ensuring polishing accuracy and enabling the mass production of qualified reflector products.

[0053] The polishing method for an ultra-precision irregularly shaped lightweight reflective mirror provided by an exemplary embodiment of the present invention includes the following steps:

[0054] Step S1: Provide a reflector, which includes a triangular prism-shaped substrate and a flat glass. The cross-sectional shape of the substrate is an isosceles right triangle, and the flat glass is formed on the hypotenuse side of the substrate.

[0055] Figure 1 This is a side view schematic diagram of the reflector structure according to an embodiment of the present invention; Figure 2 yes Figure 1 A schematic diagram of the AA cross-sectional structure; Figure 3 This is a front view schematic diagram of the reflector (auxiliary block) according to an embodiment of the present invention; Figure 4 This is a top view schematic diagram of the reflector (auxiliary block) according to an embodiment of the present invention. (Combined with...) Figures 1-4 As shown, the ultra-precision irregular-shaped lightweight reflector provided in the exemplary embodiment of the present invention consists of two parts: a triangular prism-shaped substrate 10 and a flat glass 20. The cross-sectional shape of the substrate 10 is an isosceles right triangle, and the flat glass 20 is formed on the hypotenuse side of the substrate 10.

[0056] In practical applications, the flat glass 20 is formed on a titanium alloy or titanium metal substrate 10 through a sintering process. The thickness of the flat glass 20 can be 0.5mm to 0.9mm, for example, 0.6mm, 0.7mm, 0.8mm, etc. By stabilizing the flat glass 20 through heat treatment, stress-free polishing, and depositing a large-area silver reflective film, the overall weight of the entire reflector is significantly reduced, achieving the goal of integrated lightweight design, while also achieving high reflectivity, resolution, and other performance indicators.

[0057] The substrate 10 includes two isosceles side surfaces 11 and one inclined side surface, wherein the angle between each isosceles side surface 11 and the inclined side surface is 45°, and the flat glass 20 is sintered on the inclined side surface.

[0058] In some implementations, the preset aperture value range is -0.2 to +0.2. When the surface shape of the planar glass 20, i.e. the aperture value N, reaches -0.2 to +0.2, it can be determined that the reflector has reached ultra-high precision. For example, N can be -0.15, -0.1, 0, +0.1, +0.15, etc.

[0059] Step S2: Roughly polish the flat glass 20 of the reflector.

[0060] Specifically, the surface shape of the flat glass 20 of the reflector is rough polished to achieve -2≤N≤+2, and the surface roughness of the reflector reaches Ra0.01μm.

[0061] Step S3: Place the rough-polished mirror in the ring polishing device and refine the surface shape of the flat glass 20 under preset conditions.

[0062] Figure 6 This is a top view of the ring-throwing device according to an embodiment of the present invention, as shown in the figure. Figure 6 As shown, the ring polishing device includes a rotatable asphalt mold 41, a trimming disc, and a self-rotating workpiece ring 42, wherein the trimming disc is movably disposed on the asphalt mold 41 along the radial direction of the asphalt mold 41.

[0063] The asphalt mold 41 is formed by casting a viscoelastic asphalt layer on a marble or granite base plate (with a diameter of up to 2.2m to 4m) as support. The viscoelastic properties of the asphalt can adsorb abrasive particles (such as cerium oxide) in the polishing fluid and polish the surface of the workpiece to be processed through friction.

[0064] The trimming disc is fixed to the transfer device by magnetic or mechanical clamps and suspended above the asphalt pan. The contact pressure between the trimming disc and the asphalt mold 41 is controlled by a pneumatic lever system to eliminate local depressions or bulges in the asphalt mold 41 and ensure overall flatness. For example, the trimming disc rotates at a low speed of 0.3 rpm to 2 rpm while moving in the radial direction (amplitude 0 to 140 mm), spirally scanning the surface of the asphalt mold 41. After completion, the trimming disc is lifted and stored in a non-working area.

[0065] In some embodiments, the rotational speed of the asphalt mold 41 is in the range of 2 r / min to 2.5 r / min, for example, it can be 2 r / min, 2.1 r / min, 2.2 r / min, 2.3 r / min, 2.4 r / min, 2.5 r / min or within any two of the above values.

[0066] In some embodiments, the asphalt mold 41 is made of a mixture of 60# asphalt and 65# asphalt in a weight ratio of 1:4, and the softening point of the asphalt mold 41 is 64℃. The surface shape of the asphalt mold 41 is -0.2≤N≤+0.2.

[0067] In some embodiments, the ambient temperature of the asphalt mold 41 is in the range of 22℃ to 24℃, the temperature gradient is less than 1℃ / h, and the relative humidity is in the range of 30% to 70%. Within this range of ambient temperature and temperature variation, the polishing of the reflector can be better controlled to ensure that the surface shape of the entire batch of reflectors can achieve ultra-high precision.

[0068] In some embodiments, the polishing powder in the polishing slurry includes cerium oxide or ferric oxide, and the flow rate of the polishing slurry ranges from 0.8 L / h to 1.0 L / h. Exemplarily, the concentration of the polishing slurry ranges from 0.3% to 0.5%. Exemplarily, the polishing slurry is added manually; the processing time is 3 h to 3.5 h.

[0069] For example, the outer ring surface of the workpiece ring 42 is held by the clamp 44, for example, the clamp 44 is held on the outer ring surface of the workpiece ring 42 by three rollers, and the clamp 44 can swing, and the workpiece ring 42 can rotate under the drive of the asphalt mold 41.

[0070] The polishing apparatus for an ultra-precision irregularly shaped lightweight reflector provided in an exemplary embodiment of the present invention includes a ring polishing device and a tooling for fixing the reflector.

[0071] The tooling includes a circular plate 43 that matches the workpiece ring 42. The circular plate 43 has a workpiece groove for mounting a reflector. The circular plate 43 is made of polytetrafluoroethylene. The circular plate 43 is freely disposed within the workpiece ring 42. The circular plate 43 with the reflector moves relative to the surface of the asphalt mold 41 within the workpiece ring 42. It can be understood that the flat glass 20 of the reflector is disposed on the surface of the asphalt mold 41.

[0072] For example, a rectangular workpiece groove is provided at the center of the circular plate 43 for mounting a reflector on the circular plate 43.

[0073] Figure 5A This is a bottom view of the actual structure of the reflector (auxiliary block 30) according to an embodiment of the present invention; Figure 5B This is a top view of the actual structure of the reflector (auxiliary block 30) according to an embodiment of the present invention; Figure 5C This is a front view structural schematic diagram of a reflector (auxiliary block 30) according to an embodiment of the present invention. Combined with... Figures 3-4 as well as Figures 5A-5C As shown, the above-mentioned tooling also includes four auxiliary blocks 30. The cross-section of the auxiliary blocks 30 is a right trapezoid, and they are respectively set at the four corners of the base 10 near the flat glass 20. The auxiliary blocks 30 are bonded to the isosceles side 11 of the base 10. The right-angled side 32 of the auxiliary blocks 30 is perpendicular to the flat glass 20. The distance between the right-angled side 32 of two opposite auxiliary blocks 30 is greater than the width of the flat glass 20. The distance between the bottom surface 31 of the auxiliary blocks 30 and the side edge of the base 10 away from the flat glass 20 is less than the distance between the flat glass 20 and the side edge of the base 10 away from the flat glass 20.

[0074] After the auxiliary blocks 30 are bonded to the substrate 10, the auxiliary blocks 30 on both sides of the substrate 10 are arranged in a mirror-symmetrical manner. The two auxiliary blocks 30 on both sides of the substrate 10 each have right-angled side surfaces 32 that are far apart from each other. The distance between the two right-angled side surfaces 32 is greater than the width of the flat glass 20, and the right-angled side surfaces 32 are perpendicular to the flat glass 20. That is, a part of the auxiliary block 30 extends beyond the flat glass 20 in a direction away from the substrate 10 to protect the edges and corners of the flat glass 20 and the substrate 10. Furthermore, the distance between the bottom surface 31 of the auxiliary block 30 and the side edge of the substrate 10 that is far apart from the flat glass 20 is less than the distance between the flat glass 20 and the side edge of the substrate 10 that is far apart from the flat glass 20. When the reflector is placed on the asphalt mold 41, there is a certain distance between the bottom surface 31 of the auxiliary block 30 and the asphalt surface, while the flat glass 20 can be attached to the surface of the asphalt mold 41 for polishing.

[0075] like Figure 5A and Figure 5C As shown, the auxiliary block 30 extends a portion along the length of the flat glass 20. That is, the distance between the two mutually distant end faces of the two auxiliary blocks 30 located on the same side of the substrate 10 is greater than the length of the flat glass 20. Thus, the flat glass 20 and the main body of the titanium alloy substrate 10 can be protected at the two edges at the corners of the flat glass 20 to prevent damage to the sharp corners or edges of the reflector in the event of a collision.

[0076] When the reflector is bonded to the four auxiliary blocks 30 and placed in the rectangular workpiece groove of the annular plate, the overall outer contour of the four auxiliary blocks 30 abuts against the groove wall of the workpiece groove, thereby avoiding direct contact between the reflector and the annular plate.

[0077] For example, the auxiliary block 30 is made of K9 optical glass, which is lightweight and relatively brittle, making it less likely to break when struck.

[0078] In some embodiments, the auxiliary block 30 is bonded to the reflector substrate 10, for example, by using type 1001 optical adhesive, and the area of ​​the optical adhesive on each auxiliary block 30 is 3% to 4% of the area of ​​the right-angled side surface 32.

[0079] The 1001 type optical adhesive, such as RH-SPS-1001 silicone pressure-sensitive adhesive or DOWSIL MS-1001 optical molding resin adhesive, ensures moderate adhesion between the auxiliary block 30 and the substrate 10. The adhesive layer possesses a certain elasticity to protect the reflector, and the auxiliary block 30 is easily separated from the substrate 10, thus minimizing stress on the flat glass 20. When the adhesive application area of ​​each auxiliary block 30 is 3% to 4% of the area of ​​the right-angled side surface 32 of the substrate 10, it ensures that the auxiliary block 30 does not fall off the substrate 10 during circumferential polishing and also minimizes the stress exerted by the auxiliary block 30 on the flat glass 20 of the reflector. Consequently, the change in the surface shape of the flat glass 20 before and after removing the auxiliary block 30 is negligible. Furthermore, using the aforementioned optical adhesive and application area, the auxiliary block 30 can be easily removed by gently tapping it with a wooden stake, minimizing the stress it exerts on the reflector.

[0080] For example, the application point of the 1001 type optical adhesive during bonding should be kept as far away from the flat glass 20 as possible in order to minimize the stress impact on the flat glass 20.

[0081] Step S4: Check whether the surface shape of the refined flat glass 20 reaches the preset aperture. If not, adjust the asphalt mold 41 of the ring polishing device until the surface shape of the flat glass 20 reaches the preset aperture.

[0082] For measuring the surface shape of workpieces with conventional precision, the change in surface shape with temperature is negligible. However, when measuring ultra-precision reflectors, the surface shape requirements are extremely high (N > 0.2), and the influence of ambient temperature is significant. Therefore, the entire batch of ultra-precision reflectors typically needs to be inspected at a specified temperature, such as 22°C, during acceptance testing. Furthermore, the surface shape inspection of reflectors (flat glass 20) during fine polishing requires extremely precise ambient temperature control. Surface shape inspection is conducted in an inspection room, but the ambient temperature there is usually not strictly constant and exhibits some fluctuation. Therefore, it is difficult for reflectors in the same batch to meet acceptance requirements in terms of surface shape control due to the fluctuation of the inspection environment.

[0083] In practical applications, the φ100 planar lens of the ZYGO laser interferometer is used to perform surface shape detection on the reflector. Before measurement, the reflector, interferometer lens, auxiliary measurement platform, etc. are all exposed in the measurement room for more than 2 hours to ensure the accuracy of the measurement.

[0084] After the settling period, if the temperature in the measuring room is 22℃ and the aperture value N of the plane glass 20 satisfies -0.2≤N≤+0.2, then the surface shape of the reflector is deemed qualified. After removing the auxiliary block 30 and cleaning, it proceeds to the next process.

[0085] If the temperature in the measuring room is 22℃ and the aperture value N of the flat glass 20 is greater than +0.2, the asphalt mold 41 of the ring polisher is trimmed until the surface shape of the flat glass 20 reaches the preset aperture. Specifically, the trimming disc is moved radially away from the center of the asphalt mold 41 (moving the trimming disc outward) to press the part of the asphalt mold 41 near the edge for trimming, thereby reducing the aperture value. Conversely, when the aperture value N of the flat glass 20 is less than -0.2, the trimming disc is moved towards the center of the asphalt mold 41 to increase the aperture value. The reflector is then placed in the workpiece ring 42 for further polishing until the surface shape is found to be qualified.

[0086] When the temperature in the measurement room fluctuates to some extent, rather than strictly 22℃, the aperture value detection of the flat glass 20 will be affected by temperature and may not meet the acceptance requirements.

[0087] For example, when the ambient temperature of the measurement room is T℃, and the measured aperture value is in [y1, y2], the surface shape of the plane glass 20 reaches the preset aperture; where y1 = -0.25T + 5.3, y2 = -0.25T + 5.7, and 20℃ ≤ T ≤ 24℃.

[0088] That is, at T℃, if the aperture value detected by the reflector is within the range of [y1, y2], the reflector can be judged to be qualified and meets the acceptance requirements at 22℃. However, at T℃, if the aperture value is less than y1, the dressing disc is adjusted to move towards the center of the asphalt mold 41 to increase the aperture value, and fine polishing continues until the test is qualified. Conversely, at T℃, if the aperture value is greater than y2, the dressing disc is moved outward to decrease the aperture value, and fine polishing continues until the test is qualified.

[0089] For example, the relationship between the surface shape of a reflective mirror and temperature is shown in Table 1.

[0090] Table 1. Changes in surface shape and temperature

[0091] T(℃) 20 21 22 23 24 y1 0.3 0.05 -0.2 -0.45 -0.7 y2 0.7 0.45 0.2 -0.05 -0.3

[0092] For example, when measuring the surface shape of a mirror in a measuring room, if the temperature of the measuring room is 23°C and the surface shape N of the mirror is measured to be between -0.05 and -0.45, it can be determined that the mirror reaches the preset aperture of -0.2 to +0.2 at the specified temperature of 22°C.

[0093] When the surface shape N of the reflector is measured to be -0.6 at 23℃, which is lower than the lower limit of surface shape of -0.45 corresponding to 23℃, the asphalt mold needs to be treated by raising the aperture. Usually, the trimming disc is moved inward by about 10mm.

[0094] Conversely, when the measured value of the reflector surface shape N is +0.1 at 23℃, which is higher than the upper limit of the surface shape corresponding to 23℃ (-0.45), it is necessary to reduce the aperture of the asphalt mold. Usually, the trimming disc is moved outward by 10mm, and the above steps are repeated until the reflector surface shape meets the acceptance standard.

[0095] For the upper and lower limits of aperture values ​​at other ambient temperatures, please refer to [link / reference]. Figure 7 As shown, where Figure 7 This is a scatter plot of the surface shape as a function of temperature according to an embodiment of the present invention. When the range of surface shape detection at the corresponding ambient temperature falls within... Figure 7 If the surface shape is within the wide area formed by the straight line fitted to the upper limit value and the straight line fitted to the lower limit value, it can be determined that the surface shape can meet the customer's acceptance at the specified temperature of 22℃. Otherwise, the asphalt mold should be adjusted according to the actual situation and fine polishing should continue until the above conditions are met.

[0096] An exemplary embodiment of the present invention also provides a polishing apparatus for an ultra-precision irregularly shaped lightweight reflector, for performing the above-described polishing method. The polishing apparatus includes a ring polishing device for polishing the reflector and a fixture for fixing the reflector.

[0097] The advantages of the polishing device over the prior art are the same as those of the polishing method, and will not be repeated here.

[0098] Those skilled in the art should understand that the above embodiments are merely for illustrating the present invention and are not intended to limit the scope of the invention. Those skilled in the art can make other changes or modifications based on the above disclosure, and these changes or modifications still fall within the scope of the present invention.

Claims

1. A polishing method for an ultra-precision irregularly shaped lightweight reflector, characterized in that, include: A reflector is provided, the reflector comprising a triangular prism-shaped substrate and a flat glass, the cross-section of the substrate being an isosceles right triangle, and the flat glass being formed on the hypotenuse side of the substrate; The planar glass of the reflector is subjected to rough polishing; The rough-polished mirror is placed in a ring polishing device, and the surface shape of the flat glass is refined under preset conditions; The surface shape of the refined flat glass is checked to see if it reaches the preset aperture. If not, the asphalt mold of the ring polishing device is adjusted until the surface shape of the flat glass reaches the preset aperture.

2. The polishing method according to claim 1, characterized in that, The preset aperture value ranges from -0.2 to +0.

2.

3. The polishing method according to claim 1, characterized in that, The substrate is made of titanium or a titanium alloy; and / or, The flat glass is K9 optical glass.

4. The polishing method according to claim 1, characterized in that, The ring polishing device includes a rotatable asphalt mold, a dressing disc, and a self-rotating workpiece ring, wherein the dressing disc is movably disposed on the asphalt mold along the radial direction of the asphalt mold; the step of placing the rough-polished mirror in the ring polishing device includes: The reflector is placed in the workpiece groove of the circular plate, and the circular plate is placed inside the workpiece ring. Under the rotation and swing of the workpiece ring, the circular plate drives the reflector to refine the surface shape on the asphalt mold.

5. The polishing method according to claim 4, characterized in that, The preset conditions include: the rotational speed of the asphalt mold is in the range of 2 r / min to 2.5 r / min.

6. The polishing method according to claim 4, characterized in that, The preset conditions also include: the material of the asphalt mold is a mixture of 60# asphalt and 65# asphalt in a weight ratio of 1:4, and the softening point of the asphalt mold is 64℃.

7. The polishing method according to claim 4, characterized in that, The ambient temperature range of the asphalt mold is 22℃~24℃, and the temperature gradient is less than 1℃ / h.

8. The polishing method according to claim 4, characterized in that, The step of placing the rough-polished mirror into the ring polishing device further includes: The polishing liquid is placed on the asphalt mold. The polishing liquid includes cerium oxide or ferric oxide, and the flow rate of the polishing liquid ranges from 0.8 l / h to 1.0 l / h.

9. The polishing method according to any one of claims 4-8, characterized in that, The step of adjusting the asphalt mold of the ring polisher until the surface shape of the flat glass reaches the preset aperture includes: When the surface shape of the flat glass is smaller than the preset aperture, the trimming disc moves radially toward the center of the asphalt mold to press and trim the part of the asphalt mold near the center. When the surface shape of the flat glass is larger than the preset aperture, the trimming disc moves radially away from the center of the asphalt mold to trim the area near the edge of the asphalt mold.

10. A polishing device for an ultra-precision irregularly shaped lightweight reflector, characterized in that, The polishing apparatus for performing the polishing method according to any one of claims 1-9 includes a ring polishing device for polishing a mirror and a fixture for fixing the mirror.

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