Eccentric asphalt disc device and method for smoothing intermediate frequency error of optical element

Abstract

The invention provides an eccentric asphalt disc device and method for smoothing the intermediate frequency error of an optical element, and belongs to the technical field of optical element machining. The center of the eccentric disc is fixed at the lower end of the rotating shaft; the upper end of the connecting rod is eccentrically fixed on the eccentric disc; and the asphalt disc is movably arranged at the lower end of the connecting rod and is used for smoothing the optical element through follow-up rotation when the connecting rod eccentrically rotates. The method effectively solves the technical problem of intermediate-frequency errors caused by periodicity of a motion path in the machining process, and has the advantage of being good in intermediate-frequency error suppression effect.

Description

Technical Field

[0001] This invention relates to the technical field of optical element processing, and in particular to an eccentric asphalt disk device and method for smoothing intermediate frequency errors in optical elements. Background Technology

[0002] With the rapid development of optical technology, the demand for large-aperture, high-precision aspherical optical components is becoming increasingly urgent. Optical systems have extremely strict requirements for the surface shape error accuracy of optical components across the entire frequency band. Among these requirements, the mid-frequency error affects the beam quality and Strell ratio of high-energy laser systems. Therefore, the convergence accuracy of the mid-frequency error has become a key factor in the fabrication of optical components.

[0003] While computer-controlled surface forming and polishing techniques and magnetorheological polishing techniques can efficiently remove low-frequency errors, they easily introduce mid-frequency errors during the processing. The spatial frequency of mid-frequency errors is 0.0303 mm. -1 -8.333mm -1 The root cause lies in the periodicity of the relative motion path between the processing tool and the optical element. This periodicity leads to a convolution effect during the material removal process, resulting in a mid-frequency error on the surface of the optical element. This error causes a decrease in the center brightness and an increase in the width of the imaging spot, and induces a nonlinear self-focusing effect, which harms the transmission of the laser system and, in severe cases, produces a sidelobe effect.

[0004] Therefore, it is necessary to explore a new device and method to effectively suppress intermediate frequency errors and improve the intermediate frequency surface accuracy and full-band convergence efficiency of optical elements. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned problems existing in the prior art and to provide an eccentric asphalt disk device and method for smoothing the intermediate frequency error of optical elements. Through the movable mating structure formed by the robot, the eccentric disk and the connecting rod being inserted into the asphalt disk, the asphalt disk presents a non-periodic smooth motion trajectory on the surface of the optical element, which effectively solves the technical problem of intermediate frequency error caused by the periodicity of the motion path during the processing.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The present invention provides an eccentric asphalt disk device for smoothing intermediate frequency errors of optical elements, comprising: A robot having a vertically arranged axis of rotation; An eccentric disk, the center of which is fixed at the lower end of the rotating shaft; A connecting rod, the upper end of which is eccentrically fixed to an eccentric disc; An asphalt disc, movably mounted at the lower end of a connecting rod, is used to smooth the optical element by rotating eccentrically when the connecting rod rotates.

[0007] Preferably, the follow-up rotation refers to the motion state generated by the asphalt disc under the drive of the connecting rod. When the robot drives the eccentric disc to move in a circular motion through the rotating shaft, the asphalt disc generates irregular motion under the drive of the connecting rod. The irregular motion is manifested as the random motion of the asphalt disc around its own central axis.

[0008] Preferably, the upper end of the connecting rod is slidably connected to and fixed to the bottom of the eccentric disc, and the lower end has a ball head structure; the center of the asphalt disc has an annular connecting groove with the groove opening facing upward, and the asphalt disc is movably fitted onto the ball head structure at the lower end of the connecting rod through the annular connecting groove.

[0009] Preferably, the bottom of the eccentric disk has a radially extending groove, and a slider is slidably disposed in the groove. The upper end of the connecting rod is fixed to the slider. The slider has at least one limiting hole, and the bottom of the groove has multiple fixing holes corresponding to the limiting hole. The connecting rod slides radially in the groove through the slider, and is fixed at different radial positions by a fixing bolt passing through the limiting hole and threadedly connected to any fixing hole, so as to adjust the eccentricity of the connecting rod to the center of the eccentric disk.

[0010] Preferably, the bottom of the eccentric disc is provided with a scale mark along the extension direction of the slide groove, and the scale mark is used to indicate the eccentricity value corresponding to the radial position of the connecting rod.

[0011] The present invention also provides a method for smoothing intermediate frequency errors in optical elements, which is implemented using the eccentric asphalt disk device of the present invention, and includes the following steps: S1. Based on the initial surface shape data of the optical element, the initial power spectral density characteristics of the intermediate frequency error are analyzed. S2. Based on the characteristics of the intermediate frequency error power spectral density curve and the aperture of the optical element, adjust the eccentricity of the connecting rod to determine the diameter of the asphalt disc, and preset the total processing time, rotational speed and pressure of the rotating shaft in the robot's control system. S3. Bring the bottom of the asphalt disc into contact with the surface of the optical element, and move the asphalt disc onto the lower end of the connecting rod to complete the smoothing preparation. S4. Based on the preset total processing time, rotation speed and pressure, the robot drives the asphalt disk to smooth the surface of the optical element according to the grating motion path through the eccentric disk, and drives the eccentric disk to rotate in a circular motion through the rotating shaft to realize the follow-up rotation of the asphalt disk. S5. After the preset total processing time, stop smoothing, acquire the surface shape data again, and analyze the power spectral density characteristics of the current intermediate frequency error. S6. Based on the comparison between the current power spectral density characteristics and the initial power spectral density characteristics in step S1, determine whether the intermediate frequency error meets the smoothing requirements; if not, repeat steps S2 to S5.

[0012] Furthermore, the diameter of the asphalt disk is D, and the aperture of the optical element to be processed is L. In step S2, the diameter D of the asphalt disk is determined according to the calculation formula D=k×L, where k ranges from 0.05 to 0.07.

[0013] Furthermore, a radially extending groove is provided at the bottom of the eccentric disk, and a slider is slidably disposed in the groove. The upper end of the connecting rod is fixed to the slider. A limit hole is provided on the slider, and multiple fixing holes that cooperate with the limit hole are provided at the bottom of the groove. In step S2, the slider is fixed at the required radial position by passing a fixing bolt through the limit hole and threadedly connecting it to any of the fixing holes, thereby realizing the adjustment of the eccentricity of the connecting rod. The eccentricity is e, where e = 5 mm.

[0014] Furthermore, the total processing time preset in the robot's control system is determined based on the dwell time of each path point on the grating motion path, and the dwell time is determined based on the amount of material removed at each path point.

[0015] Furthermore, the preset rotational speed of the rotating shaft is 200 rpm, and the preset pressure is 9.6 N.

[0016] The advantages of using this invention are: 1. The present invention provides an eccentric asphalt disk device for smoothing intermediate frequency errors of optical components. First, the asphalt disk is movably set at the lower end of the connecting rod, so that the asphalt disk can achieve multi-degree-of-freedom attitude adaptive adjustment during the movement process. This effectively breaks the periodic error caused by the fixed motion trajectory in traditional processing, ensures the continuous optimized fit between the asphalt disk and the surface of the optical component during the processing, and significantly improves the suppression effect of intermediate frequency errors.

[0017] Secondly, the structural design of the upper end of the connecting rod being eccentrically fixed on the eccentric disk can more effectively smooth the machining trajectory.

[0018] In summary, the present invention, through its structural design of the asphalt disk being movably positioned at the lower end of the connecting rod and the upper end of the connecting rod being eccentrically fixed to the eccentric disk, differs from the prior art where the polishing tool simply revolves around a fixed axis. The eccentric design and movable arrangement of the present invention superimpose eccentric rotation and adaptive follow-up rotation on the surface of the optical element. These two movements combine to form a complex non-periodic motion trajectory, fundamentally breaking the periodic characteristics of traditional smooth processing paths. This effectively solves the mid-frequency error problem caused by the periodicity of the motion path during processing, significantly improving the mid-frequency surface accuracy and full-band convergence efficiency of the optical element.

[0019] 2. In this invention, a reliable spherical movable connection and free rotation at multiple angles are achieved through the matching structure of the ball head structure and the annular connecting groove.

[0020] 3. In this invention, the sliding fit structure between the slider and the groove enables precise and continuous adjustment of the eccentricity; at the same time, the fixing bolt locking structure reliably fixes the connecting rod in the preset working position, thereby ensuring the stability of the asphalt disc during rotation.

[0021] 4. In this invention, the eccentricity parameter can be visualized and precisely adjusted through the scale marking structure.

[0022] 5. The method for smoothing intermediate frequency errors in optical elements provided by this invention firstly analyzes the initial power spectral density characteristics of the intermediate frequency error based on the initial surface shape data of the optical element, providing a precise basis for subsequent processing. Next, based on this characteristic and the aperture of the optical element, the eccentricity of the connecting rod is adjusted, and a suitable asphalt disk diameter is selected. Simultaneously, a reasonable rotation speed, pressure, and total processing time are preset in the robot control system. During processing, the asphalt disk moves along a grating path on the surface of the optical element, and the rotating shaft drives the eccentric disk to rotate circumferentially and the connecting rod to rotate eccentrically, achieving the follow-up rotation of the asphalt disk. After the preset total processing time, the surface shape data is acquired again, and the power spectral density characteristics of the current intermediate frequency error are analyzed and compared with the initial characteristics. If the smoothing requirements are not met, the aforementioned steps are repeated.

[0023] This method, through a series of targeted steps, can break the periodicity of relative motion paths in existing processing technologies, effectively suppress the generation of intermediate frequency errors from the root, significantly reduce the power spectral density of intermediate frequency errors, improve the intermediate frequency surface accuracy of optical components, and thus enhance the convergence efficiency of optical components across the entire frequency band, providing a reliable guarantee for the production of high-quality, large-aperture, high-precision optical components. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is an enlarged schematic diagram of the connection structure of the rotating shaft, eccentric disk, and asphalt disk in this invention; Figure 3 This is a schematic diagram of the movable fit structure between the connecting rod and the annular connecting groove in this invention; Figure 4 This is a bottom view of the disk structure in this invention; Figure 5 This is the power spectral density (PSD) curve of the processed material in Experiment 2 of this invention. Figure 6The image shows the power spectral density (PSD) curve after processing using conventional methods in Experiment 1.

[0025] The following are the labels in the diagram: 1. Robot, 10. Rotary axis, 2. Asphalt disc, 200. Annular connecting groove, 3. Eccentric disc, 300. Ball head structure, 30. Connecting rod, 31. Slide groove, 32. Slider, 33. Scale marking, 4. Polishing fluid circulation unit, 40. Circulation pump, 41. Discharge pipe, 42. Return pipe, 5. Workpiece table, 6. Fixing bolt. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. For ease of description, the description of the relative positional relationships of each component is based on the layout of the accompanying drawings, such as the positional relationships of front, back, top, bottom, left, right, etc., which are determined according to the layout direction of the accompanying drawings.

[0027] Example 1 As a basic embodiment of the present invention, Embodiment 1 provides an eccentric asphalt disk device for smoothing the intermediate frequency error of optical elements, such as... Figure 1-2 As shown, the device includes a robot 1, an eccentric disk 3, a connecting rod 30, and an asphalt disk 2. Their specific structures and connections are as follows: Robot 1 has a vertically arranged rotation axis 10. The rotation axis 10 can provide continuous rotational power and its rotation speed can be precisely controlled by the control system of robot 1.

[0028] The center of the eccentric disk 3 is fixed at the lower end of the rotating shaft 10. As the core transmission component of the entire drive unit, it is used to smoothly transmit the power of the rotating shaft 10 to the connecting rod 30 and the asphalt disk 2 below, and to provide a structural basis for eccentricity adjustment.

[0029] The upper end of the connecting rod 30 is eccentrically fixed to the eccentric disk 3. This eccentric design structure is key to generating the composite motion trajectory of the device of the present invention, and can more effectively smooth the processing trajectory.

[0030] The asphalt disk 2 is movably positioned at the lower end of the connecting rod 30, meaning that the connecting rod 30 and the asphalt disk 2 are not fixedly connected. It is used to smooth the optical element by following the eccentric rotation of the connecting rod 30. The bottom of the asphalt disk 2 is the working surface, preferably made of Globe 64# asphalt, used for contact with the surface of the optical element to be processed.

[0031] The following rotation refers to the motion state of the asphalt disk 2 under the drive of the connecting rod 30. When the robot 1 drives the eccentric disk 3 to move in a circular motion through the rotating shaft 10, the asphalt disk 2 generates irregular motion under the drive of the connecting rod 30. This irregular motion is manifested as the random motion of the asphalt disk 2 around its own central axis.

[0032] Therefore, the present invention, through the structural design of the asphalt disk 2 being movably positioned at the lower end of the connecting rod 30 and the upper end of the connecting rod 30 being eccentrically fixed to the eccentric disk 3, enables the asphalt disk 2 to achieve multi-degree-of-freedom adaptive attitude adjustment during movement, and can more effectively smooth the processing trajectory. Compared with the existing technology where the polishing tool only revolves around a fixed axis, the eccentric design and movable structural design of the present invention superimpose the motion of the asphalt disk 2 on the surface of the optical element with circular rotation, eccentric rotation, and adaptive follow-up rotation. These three motions combine to form a complex non-periodic motion trajectory, fundamentally breaking the periodic characteristics of the traditional smooth processing path, thereby significantly improving the suppression effect of mid-frequency error.

[0033] Example 2 This embodiment optimizes the eccentricity adjustment structure between the eccentric disc 3 and the connecting rod 30, as well as the movable fit structure between the connecting rod 30 and the asphalt disc 2.

[0034] like Figure 2-3 As shown, the upper end of the connecting rod 30 is slidably connected to and fixed to the bottom of the eccentric disk 3, while the lower end has a ball-head structure 300. The center of the asphalt disk 2 has an annular connecting groove 200 with its opening facing upwards. The asphalt disk 2 is movably fitted onto the ball-head structure 300 at the lower end of the connecting rod 30 via the annular connecting groove 200. That is, the ball-head structure 300 is accommodated within the annular connecting groove 200, achieving a connection relationship where the asphalt disk 2 is movably positioned at the lower end of the connecting rod 30, thereby enabling the asphalt disk 2 to achieve multi-degree-of-freedom attitude self-adaptation.

[0035] The aforementioned activity settings are not limited to the aforementioned ball joint and annular connecting groove cooperation. Any equivalent structure that enables the connecting rod 30 to form a movable cooperation with the center of the asphalt disk 2 and allows the asphalt disk 2 to achieve multi-degree-of-freedom attitude self-adaptation is applicable to this invention. For example, the connecting rod 30 is designed as a cylinder, and the annular connecting groove 200 is designed as a ball-and-socket structure fixed at the center of the top of the asphalt disk 2.

[0036] Furthermore, such as Figure 4As shown, the bottom of the eccentric disk 3 has a radially extending groove 31, and a slider 32 is slidably disposed in the groove 31. The upper end of the connecting rod 30 is fixed to the slider 32. The slider 32 has at least one limiting hole (not shown in the figure), and the bottom of the groove 31 has multiple fixing holes (not shown in the figure) corresponding to the limiting hole. The connecting rod 30 slides radially in the groove 31 through the slider 32, and is fixed at different radial positions by a fixing bolt 6 passing through the limiting hole and threadedly connected to any of the fixing holes, so as to adjust the eccentricity of the connecting rod 30 to the center of the eccentric disk 3.

[0037] Further, continue to refer to Figure 4 The bottom of the eccentric disk 3 is provided with a scale mark 33 along the extension direction of the slide groove 31. The scale mark 33 is used to indicate the eccentricity value corresponding to the radial position of the connecting rod 30.

[0038] Continue to refer to Figure 1 The device of the present invention further includes a workpiece stage 5 for fixing optical elements and a polishing fluid circulation unit 4. The workpiece stage 5 is disposed below the asphalt disk 2; the polishing fluid circulation unit 4 includes a circulation pump 40, an outlet pipe 41 and a return pipe 42.

[0039] The outlet of the circulating pump 40 is connected to the liquid outlet pipe 41, and the inlet is connected to the liquid return pipe 42. The liquid outlet pipe 41 is preferably fixed on the robot body 1, and the spray outlet of the liquid outlet pipe 41 points to the processing area on the surface of the optical element. It is used to continuously supply polishing liquid to the processing area to remove the polishing liquid, ensure that a stable liquid film is formed between the asphalt disk 2 and the surface of the optical element, stabilize the flow rate, and assist in heat dissipation. The inlet end of the liquid return pipe 42 extends into the workpiece stage 5 to recover excess polishing liquid during the smoothing operation.

[0040] Example 3 This embodiment provides a method for smoothing the intermediate frequency error of optical elements. This method is implemented using the device structures in Embodiments 1 and 2, and specifically includes the following steps: S1. Based on the initial surface shape data of the optical element, the initial power spectral density characteristics of the intermediate frequency error are analyzed.

[0041] In this step, the initial surface shape data is obtained by interferometer detection and imported into the intermediate frequency error analysis software to complete the analysis, thereby obtaining the initial power spectral density characteristics of the intermediate frequency error of the optical element to be processed.

[0042] S2. Based on the characteristics of the intermediate frequency error power spectral density curve and the aperture of the optical element, adjust the eccentricity of the connecting rod 30 to determine the diameter of the asphalt disc 2, and preset the total processing time, as well as the rotation speed and pressure of the rotating shaft 10 in the control system of the robot 1.

[0043] In this step, the preset total processing time refers to the total duration required for the asphalt disk to cover the entire surface area of the optical element along the preset trajectory.

[0044] The preset rotational speed range of the rotating shaft 10 is 100 rpm - 500 rpm, and the preset pressure range is 5 N - 15 N. Preferably, the preset rotational speed is 200 rpm, and the preset pressure is 9.6 N.

[0045] S3. Contact the bottom of the asphalt disk 2 with the surface of the optical element, and sleevethe asphalt disk 2 movably on the lower end of the connecting rod 30 to complete the smoothing preparation; S4. Based on the preset total processing time, rotational speed, and pressure, the robot 1 drives the asphalt disk 2 to perform smoothing on the surface of the optical element along the grating motion path through the eccentric disk 3, and synchronously drives the eccentric disk 3 to perform a circular motion through the rotating shaft 10, realizing the follow-up rotation of the asphalt disk 2, so as to generate an aperiodic smoothing motion trajectory on the surface of the optical element.

[0046] S5. Stop smoothing after the preset total processing time, obtain the surface shape data again, and analyze to obtain the power spectral density characteristics of the current mid-frequency error; S6. According to the comparison result between the current power spectral density characteristics and the initial power spectral density characteristics in step S1, judge whether the mid-frequency error meets the smoothing requirements; if not, repeat steps S2 to S5.

[0047] Furthermore, the diameter of the asphalt disk is determined according to the caliber of the optical element to be processed and the surface shape data. Preferably, the diameter of the asphalt disk 2 is D, and the caliber of the optical element to be processed is L. In step S2, the diameter D of the asphalt disk 2 is determined according to the calculation formula D = k×L, where the range value of k is 0.05 to 0.07. Preferably, when the caliber of the optical element to be processed is 1200 mm, an asphalt disk with D = 80 mm can be selected; when the caliber of the optical element to be processed is 400 mm, an asphalt disk with D = 25 mm can be selected.

[0048] Furthermore, as Figure 4 shown, a radially extending chute 31 is provided at the bottom of the eccentric disk 3, a slider 32 is slidably arranged in the chute 31, and the upper end of the connecting rod 30 is fixed to the slider 32; a limiting hole is provided on the slider 32, and a plurality of fixing holes matching the limiting hole are provided at the bottom of the chute 31. In step S2, the slider 32 is fixed at the required radial position by passing a fixing bolt 6 through the limiting hole and threadedly connecting it with any fixing hole, so as to realize the adjustment of the eccentricity of the connecting rod 30. Among them, the eccentricity is e, and the range value of the eccentricity e satisfies 0 mm < e ≤ 10 mm. Preferably, the value of the eccentricity e is 5 mm. This adjustment mechanism ensures that when processing optical elements of different sizes, the asphalt disk 2 can generate an aperiodic smoothing motion trajectory on the surface of the optical element during the follow-up rotation, and finally effectively suppresses the mid-frequency error.

[0049] Furthermore, the total processing time preset in the control system of robot 1 is determined based on the dwell time at each path point on the grating motion path, and the dwell time is determined based on the amount of material removed at each path point. In this way, the processing can achieve a balance between material removal efficiency and surface quality, thereby achieving efficient and stable mid-frequency error suppression.

[0050] In summary, through the above steps, this invention solves the problem of mid-frequency error accumulation caused by periodic motion trajectories in traditional optical component manufacturing. This method dynamically adjusts the matching relationship between the eccentricity and the diameter of the asphalt disk according to the aperture of the optical component to be processed, and combines this with the follow-up rotational motion of the asphalt disk with multiple degrees of freedom, effectively breaking the periodic characteristics of the processing path in conventional processing methods. This generates a non-periodic, smooth motion trajectory on the surface of the optical component, significantly reducing the power spectral density of the mid-frequency error. Ultimately, this achieves a significant improvement in the surface quality of the optical component, providing a reliable technical solution for the manufacture of high-precision optical components.

[0051] To verify the effectiveness of the method for smoothing the intermediate frequency error of optical elements in this embodiment, a comparative experiment was conducted. Two optical elements of the same aperture (L=430mm) were selected for the experiment. Smoothing was performed using both the conventional method with zero eccentricity and the method of this invention with non-zero eccentricity, respectively. The surface shape data of the optical elements before and after processing were detected using an interferometer, and the changes in the power spectral density (PSD) curve were analyzed using intermediate frequency error analysis software. The specific experimental design and results are as follows: Experimental Design: Experiment 1: A conventional non-eccentric machining method with an eccentricity e=0mm was used. Specific parameters were set as follows: asphalt disc diameter 25mm, rotary shaft speed 200 rpm, and machining pressure 9.6 N. The surface shape data collected and analyzed after machining are shown below. Figure 6 As shown, the power spectral density (PSD) curve failed to completely suppress the power spectral density below the technical specification requirement line (indicated by a straight line in the figure).

[0052] Experiment 2: Using the apparatus and method of this invention, the eccentricity e was set to 5 mm, while other parameters remained consistent with Experiment 1. The power spectral density (PSD) curve analysis results are as follows: Figure 5 As shown, the entire power spectral density (PSD) curve is below the technical specification requirement line (indicated by a straight line in the figure), confirming that the intermediate frequency error suppression effect is qualified.

[0053] Experimental results:

[0054] Experimental conclusion: Compared with Experiment 1, which used zero eccentricity, Experiment 2, which used the eccentric design of the present invention, significantly improved the suppression of intermediate frequency error, confirming that the eccentric design has a significant and crucial role in suppressing intermediate frequency error.

[0055] The above description is merely a specific embodiment of the present invention. Any feature disclosed in this specification may be replaced by other equivalent or similar features unless otherwise specified. All features or steps in the disclosed methods or processes may be combined in any way, except for mutually exclusive features and / or steps.

Claims

1. An eccentric asphalt disk device for smoothing intermediate frequency errors of optical elements, characterized in that, include: Robot (1), the robot (1) having a vertically arranged rotation axis (10); An eccentric disk (3) is fixed at the lower end of a rotating shaft (10). Connecting rod (30), the upper end of which is eccentrically fixed on eccentric disk (3); Asphalt disc (2), which is movably disposed at the lower end of the connecting rod (30), is used to smooth the optical element by following the rotation when the connecting rod (30) rotates eccentrically.

2. The eccentric asphalt disk device for smoothing intermediate frequency errors of optical elements according to claim 1, characterized in that: The following rotation refers to the motion state generated by the asphalt disk (2) under the drive of the connecting rod (30). When the robot (1) drives the eccentric disk (3) to move in a circular motion through the rotating shaft (10), the asphalt disk (2) generates irregular motion under the drive of the connecting rod (30). The irregular motion is manifested as the random motion of the asphalt disk (2) around its own central axis.

3. The eccentric asphalt disk device for smoothing intermediate frequency errors of optical elements according to claim 1, characterized in that: The upper end of the connecting rod (30) is slidably connected to the bottom of the eccentric disk (3) and can be fixed, and the lower end is a ball head structure (300); the center of the asphalt disk (2) is fixed with an annular connecting groove (200) with the groove opening facing upward, and the asphalt disk (2) is movably sleeved on the ball head structure (300) at the lower end of the connecting rod (30) through the annular connecting groove (200).

4. The eccentric asphalt disk device for smoothing intermediate frequency errors of optical elements according to claim 3, characterized in that: The bottom of the eccentric disk (3) is provided with a radially extending slide groove (31), and a slider (32) is slidably arranged in the slide groove (31). The upper end of the connecting rod (30) is fixed on the slider (32). At least one limiting hole is provided on the slider (32), and multiple fixing holes corresponding to the limiting hole are provided at the bottom of the slide groove (31). The connecting rod (30) slides radially in the slide groove (31) through the slider (32), and is fixed at different radial positions by a fixing bolt (6) passing through the limiting hole and threadedly connected to any fixing hole, so as to adjust the eccentricity of the connecting rod (30) to the center of the eccentric disk (3).

5. The eccentric asphalt disk device for smoothing intermediate frequency errors of optical elements according to claim 3, characterized in that: The bottom of the eccentric disk (3) is provided with a scale mark (33) along the extension direction of the slide groove (31). The scale mark (33) is used to indicate the eccentricity value corresponding to the radial position of the connecting rod (30).

6. A method for smoothing intermediate frequency errors in optical elements, implemented using the eccentric asphalt disk device as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Based on the initial surface shape data of the optical element, the initial power spectral density characteristics of the intermediate frequency error are analyzed. S2. Based on the characteristics of the intermediate frequency error power spectral density curve and the aperture of the optical element, adjust the eccentricity of the connecting rod (30), determine the diameter of the asphalt disc (2), and preset the total processing time, as well as the rotation speed and pressure of the rotating shaft (10) in the control system of the robot (1). S3. Make the bottom of the asphalt disk (2) contact the surface of the optical element, and make the asphalt disk (2) movably sleeved on the lower end of the connecting rod (30) to complete the smoothing preparation; S4. Based on the preset total processing time, rotation speed and pressure, the robot (1) drives the asphalt disk (2) to smooth the surface of the optical element according to the grating motion path through the eccentric disk (3), and drives the eccentric disk (3) to rotate in a circular motion through the rotating shaft (10) to realize the follow-up rotation of the asphalt disk (2). S5. After the preset total processing time, stop smoothing, acquire the surface shape data again, and analyze the power spectral density characteristics of the current intermediate frequency error. S6. Based on the comparison between the current power spectral density characteristics and the initial power spectral density characteristics in step S1, determine whether the intermediate frequency error meets the smoothing requirements; if not, repeat steps S2 to S5.

7. The method for smoothing intermediate frequency errors in optical elements according to claim 6, characterized in that: The diameter of the asphalt disk (2) is D, and the aperture of the optical element to be processed is L. In step S2, the diameter D of the asphalt disk (2) is determined according to the calculation formula D=k×L, where k ranges from 0.05 to 0.

07.

8. The method for smoothing intermediate frequency errors in optical elements according to claim 7, characterized in that: The bottom of the eccentric disk (3) is provided with a radially extending slide groove (31), and a slider (32) is slidably arranged in the slide groove (31). The upper end of the connecting rod (30) is fixed on the slider (32). A limit hole is provided on the slider (32), and the bottom of the slide groove (31) is provided with multiple fixing holes that cooperate with the limit hole. In step S2, the slider (32) is fixed at the required radial position by passing the fixing bolt (6) through the limit hole and threadedly connecting it to any fixing hole, thereby realizing the adjustment of the eccentricity of the connecting rod (30). The eccentricity is e, e=5mm.

9. A method for smoothing intermediate frequency errors in optical elements according to claim 6, characterized in that: The total processing time preset in the control system of the robot (1) is determined based on the dwell time of each path point on the grating motion path, and the dwell time is determined based on the amount of material removed at each path point.

10. A method for smoothing intermediate frequency errors in optical elements according to claim 6, characterized in that: The preset rotational speed of the rotating shaft (10) is 200 rpm, and the preset pressure is 9.6 N.

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