Off-axis aspherical mirror surface machining process based on milling and grinding machine

Abstract

The invention discloses an off-axis aspheric mirror surface processing technology based on a milling and grinding machine, which comprises the following steps of: calculating a closest spherical radius according to a vertex curvature radius R, an aspheric coefficient K and a caliber parameter of a required open surface, fitting an aspheric surface according to the closest spherical radius, calculating an aspheric degree, fitting the aspheric surface and the aspheric degree, and selecting a processing mode. Determining the rotating speed of a rotary table according to the actual aperture of the blank and the aperture of the aspheric surface; determining the step pitch of the machining tool according to the material of the blank; determining the machining range of the machining tool according to the actual size of the blank; establishing a coordinate system, centering and fixing the blank according to whether the mirror surface to be machined is off-axis or not; according to the machining process, the machining content is determined at a time by means of multiple times of calculation on the mirror surface needing to be machined in the earlier stage of machining, the one-step milling and grinding process from the blank mirror surface to the off-axis aspheric surface is achieved, the machining error is small, the machining efficiency is high, and the machining process practical value is high.

Description

Technical Field

[0001] The invention relates to the technical field of off-axis aspheric mirror surface processing, in particular to an off-axis aspheric mirror surface processing technology based on a milling machine. Background Art

[0002] The surface curvature of aspherical lenses is different from that of ordinary spherical lenses. In order to pursue the thinness of lenses, it is necessary to change the curvature of the lenses. In the past, the spherical design increased aberration and deformation, resulting in obvious undesirable phenomena such as unclear images, distorted vision, and narrow field of view. Now the aspherical design corrects the image and solves the problems of distorted vision. At the same time, it makes the lenses lighter, thinner, and flatter. Moreover, it still maintains excellent impact resistance, allowing the wearer to use it safely.

[0003] Traditional spherical lenses have distortion around the lens, which limits the wearer's field of vision. In an era of continuous technological advancement, aspherical design, an optical miracle, reduces the edge aberration of the lens to the lowest, making it possible to meet the needs of customers with a wide field of vision. Aspherical lenses have a flatter base curve, are lighter, and look more natural and beautiful. In the case of high diopter, it can reduce eye deformation. For consumers with high vision, it may be more appropriate to choose aspherical lenses.

[0004] The surface curvature of the aspherical lens is aspherical. The advantages of this design over the spherical design lens are:

[0005] More clarity

[0006] The aspherical lenses that have undergone a unique coating treatment have a perfect visual performance, presenting a clearer and more comfortable visual effect.

[0007] Easier

[0008] After wearing aspherical lenses, you will hardly feel their presence. It reduces weight for your eyes and you can enjoy the ease and freedom it brings you.

[0009] More natural

[0010] The aspherical design is more natural, with less visual distortion and more realistic vision.

[0011] In the field of optics, mirror milling technology is mainly used to process optical lenses, which are mainly divided into spherical, aspherical and flat lenses. With the continuous development of society and the optical industry, aspherical lenses are widely used in light collection, projection, lighting, detection and focusing, especially in the military, civil and aerospace fields. More aspherical lenses will be needed in the future.

[0012] The first step in the processing of all lenses is to open the blank. The existing off-axis aspheric blank opening technology is generally divided into four steps. The first step is to remove the off-axis aspheric lens blank from the mother lens blank, the second step is to mill the blank surface to be processed into a standard shape, the third step is to mill the standard shape into a near spherical surface, and the fourth step is to mill the near spherical surface into an aspheric surface. Each step requires the blank to be re-placed, which leads to low overall processing efficiency. Therefore, an improved technology is urgently needed to solve this problem in the existing technology. Summary of the invention

[0013] The purpose of the present invention is to provide an off-axis aspheric mirror processing technology which utilizes multiple calculations of the required mirror surface in the early stage of processing to determine the processing content at one time, realizes a one-step process from the blank mirror surface to the off-axis aspheric surface, has small processing error, high processing efficiency, and high practical value of processing technology, so as to solve the problems raised in the above-mentioned background technology.

[0014] To achieve the above object, the present invention provides the following technical solution: an off-axis aspheric mirror processing process based on a milling machine, characterized in that:

[0015] Step 1: Calculate the closest spherical radius according to the vertex curvature radius R, aspheric coefficient K, and aperture parameters of the off-axis aspheric mirror surface;

[0016] Step 2: Fit the aspheric surface according to the radius of the closest off-axis aspheric mirror surface and calculate the asphericity;

[0017] Step 3: Select the processing method based on the fitted off-axis aspheric mirror surface and asphericity;

[0018] Step 4: Determine the processing tool and speed according to the processing method;

[0019] Step 5: Determine the rotation speed of the turntable according to the actual diameter of the blank and the diameter of the aspherical surface;

[0020] Step 6: Determine the step length of the machining tool according to the blank material;

[0021] Step 7: Determine the processing range of the processing tool according to the actual size of the blank;

[0022] Step 8: Establish a coordinate system, center and fix the blank according to whether the mirror surface to be processed is off-axis;

[0023] Step 9: Start processing after confirming that the above steps are correct and the on-site situation is safe;

[0024] Preferably, when calculating the aspheric radius of the off-axis aspheric mirror, attention should be paid to the concavity and convexity of the open surface, the positive and negative values ​​of the aspheric coefficient K, K>0, the open surface is convex, K<0, the open surface is concave;

[0025] The vertex curvature radius R calculated for off-axis aspheric mirrors needs to be increased or decreased based on the requirements of the drawing. The smaller the R value, the greater the increase or decrease required, and the larger the R value, the smaller the increase or decrease required.

[0026] Preferably, the calculated closest spherical radius in step 2 should be ensured to be within the range of -0.03 to +0.03;

[0027] When the calculated asphericity is not within this range, the vertex curvature radius R is readjusted to calculate the radius closest to the spherical surface, and the calculated asphericity is adjusted to be within the range of -0.03 to +0.03.

[0028] Preferably, the step four

[0029] K9 material, NBK7 material, softer quartz material, etc. choose electroplated diamond tools;

[0030] For microcrystalline materials, single crystal silicon materials, and harder quartz materials, bronze sintered diamond tools are selected;

[0031] A resin wheel cutter is used at the end of processing.

[0032] Preferably, the step five

[0033] When starting processing, start with a low-number tool, and then use a high-number tool for subsequent processing. The tool step distance becomes smaller and smaller as the mesh number increases. The step distance is determined according to the number of tools.

[0034] Preferably, the step seven

[0035] The off-axis mirror uses the grating processing method, and the processing range is expanded by about 5%. When the mirror surface to be processed is a convex mirror surface, the tool for processing the convex mirror off-axis mirror must be raised by a vector height (the vector height of the convex mirror).

[0036] Preferably, step eight

[0037] According to the required processing mirror surface is an off-axis aspherical mirror surface, the blank is established with a coordinate system, centered and fixed.

[0038] Equal division: mark the blank into equal parts;

[0039] Fixing: Use rosin wax to fix the blank on the turntable;

[0040] Centering: If it is a circular blank, straighten the axis of the blank outward and align it with the tool position so that the two overlap on the same straight line;

[0041] If it is a rectangular blank, align one side of the blank with the tool position so that the two overlap on the same straight line, and then use a micrometer to find the center;

[0042] Establish a coordinate system: Set the center found by the micrometer as the coordinate origin and establish a coordinate system before processing.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] (1) When the absolute value of asphericity is 0, the processing difficulty is the lowest and the processing effect is the best. Therefore, it can be judged that the lower the absolute value of asphericity, the lower the processing difficulty and the better the processing effect;

[0045] (2) This processing technology uses multiple calculations of the required mirror surface in the early stage of processing to determine the processing content at one time, realizing a one-step process from the blank mirror surface to the off-axis aspheric surface. It has small processing errors and high processing efficiency, and has high practical value of processing technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a schematic diagram of the off-axis aspheric mirror processing process of the present invention;

[0047] Figure 2 It is a schematic diagram of the aspheric curve of the present invention;

[0048] Figure 3 It is a schematic diagram of the processing trajectory curve of the x-axis changing with time of the present invention;

[0049] Figure 4 It is a schematic diagram of the processing trajectory curve of the y-axis changing with time of the present invention;

[0050] Figure 5 It is a schematic diagram of the machining trajectory curve of the z-axis changing with time of the present invention;

[0051] Figure 6 It is a schematic diagram of the off-axis aspheric surface of the present invention. DETAILED DESCRIPTION

[0052] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions 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. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] See also Figure 1 -picture Figure 6 The present invention provides a technical solution: an off-axis aspheric mirror processing process based on a milling machine,

[0054] The closest spherical radius is calculated based on the vertex curvature radius R, aspheric coefficient K, and aperture parameters of the off-axis aspheric mirror surface.

[0055] The aspheric surface is fitted according to the radius of the closest off-axis aspheric mirror surface, and the asphericity is calculated;

[0056] Select the processing method based on the fitted off-axis aspheric mirror surface and asphericity;

[0057] Determine the machining tool and speed according to the machining method;

[0058] Determine the rotation speed of the turntable according to the actual diameter of the blank and the diameter of the aspherical surface;

[0059] Determine the step length of the machining tool according to the blank material;

[0060] Determine the processing range of the machining tool according to the actual size of the blank;

[0061] According to whether the mirror surface to be processed is off-axis, the coordinate system is established, centered and fixed for the blank;

[0062] Start processing after confirming that the above steps are correct and the on-site situation is safe.

[0063] When calculating the aspheric radius of an off-axis aspheric mirror, it is necessary to pay attention to the convexity of the open surface and the positive and negative values ​​of the aspheric coefficient K. If K>0, the open surface is convex, and if K<0, the open surface is concave.

[0064] The vertex curvature radius R calculated for off-axis aspheric mirrors needs to be increased or decreased based on the requirements of the drawing to reduce the impact of the marginal effect. It has nothing to do with the concavity of the open surface. The smaller the R value, the greater the increase or decrease required, and the larger the R value, the smaller the increase or decrease.

[0065] According to the calculated closest spherical radius, the calculated asphericity should be ensured to be within the range of -0.03 to +0.03. Within this range, the lower the absolute value of the asphericity, the lower the PV value of the surface opening, and the higher the accuracy (PV value is one of the indicators for evaluating the surface shape of the mirror. The surface shape accuracy of the optical component is an important indicator for evaluating whether it meets the requirements. Generally, the peak-to-valley PV value is used as the evaluation standard, that is, the difference between the highest point and the lowest point on the component surface.

[0066] The calculated closest spherical radius is adjusted to adjust the calculated asphericity within the range of -0.03 to +0.03. When the calculated asphericity is not within this range, the vertex curvature radius R needs to be readjusted.

[0067] Embodiment 1,

[0068] Adjust the vertex curvature radius R, adjust the calculated closest spherical radius, and adjust the calculated asphericity to -0.03;

[0069] Embodiment 2,

[0070] Adjust the vertex curvature radius R, adjust the calculated closest spherical radius, and adjust the calculated asphericity to -0.02;

[0071] Embodiment 3,

[0072] Adjust the vertex curvature radius R, adjust the calculated closest spherical radius, and adjust the calculated asphericity to -0.01;

[0073] Embodiment 4,

[0074] Adjust the vertex curvature radius R, adjust the calculated closest spherical radius, and adjust the calculated asphericity to 0;

[0075] Embodiment 5,

[0076] Adjust the vertex curvature radius R, adjust the calculated closest spherical radius, and adjust the calculated asphericity to 0.01;

[0077] Embodiment 6,

[0078] Adjust the vertex curvature radius R, adjust the calculated closest spherical radius, and adjust the calculated asphericity to 0.02;

[0079] Embodiment 7,

[0080] Adjust the vertex curvature radius R, adjust the calculated closest spherical radius, and adjust the calculated asphericity to 0.03;

[0081] Through the above embodiments, it is found that when the absolute value of the asphericity in Embodiment 4 is 0, the processing difficulty is the lowest and the processing effect is the best. Therefore, it can be judged that the lower the absolute value of the asphericity, the lower the processing difficulty and the better the processing effect.

[0082] The lens is an off-axis mirror aspheric surface, which is processed by the aspheric grating grinding method. According to the normal direction (perpendicular to the generatrix direction), the off-axis mirror aspheric surface is a convex mirror, which is processed from the outer circle to the inner circle of the blank, and the concave mirror is processed from the inner circle to the outer circle of the blank.

[0083] The processing tool and rotation speed are determined according to the processing method. Electroplated diamond tools are selected for K9 materials, NBK7 materials, and softer quartz materials. Bronze sintered diamond tools are selected for microcrystalline materials, single crystal silicon materials, and harder quartz materials. Resin wheel tools are used at the end of processing to reduce the depth of the surface damage layer and increase the efficiency of the subsequent polishing process. The rotation speed is determined according to the hardness of the material. The harder the material, the higher the rotation speed, and the softer the material, the lower the rotation speed. The turntable speed varies with the actual caliber of the blank and the aspherical caliber. The smaller the caliber, the higher the rotation speed, and the larger the caliber, the lower the rotation speed.

[0084] When starting processing, start with a low number of tools, and then use a high number of tools for processing. The tool step distance becomes smaller and smaller as the mesh number increases. Determine the step distance according to the number of tools.

[0085] The off-axis mirror uses the grating processing method, and the processing range is expanded by about 5%. When the mirror surface to be processed is a convex mirror surface, the tool for processing the convex mirror off-axis mirror must be raised by a vector height (the vector height of the off-axis aspheric convex mirror currently detected).

[0086] According to the off-axis aspheric mirror surface to be processed, the coordinate system is established, centered and fixed for the blank, the blank is divided and marked equally, and the blank is fixed on the turntable with rosin wax. If it is a circular blank, the axis of the blank is straightened outward and aligned with the tool position so that the two coincide on the same straight line. If it is a rectangular blank, one side of the blank is aligned with the tool position so that the two coincide on the same straight line, and then the micrometer is used to find the center, and the center found by the micrometer is set as the coordinate origin and the coordinate system is established, and then processing is carried out. After confirming that the above steps are correct and the on-site situation is safe, processing can be started.

[0087] This processing technology uses multiple calculations of the required mirror surface in the early stage of processing to determine the processing content at one time, realizing a one-step process from the blank mirror surface to the off-axis aspheric surface. It has small processing errors and high processing efficiency, and has high practical value of processing technology.

[0088] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An off-axis aspheric mirror processing process based on a milling machine, characterized in that: Said Step 1: Calculate the closest spherical radius according to the vertex curvature radius R, aspheric coefficient K, and aperture parameters of the off-axis aspheric mirror surface; Step 2: Fit the aspheric surface according to the radius of the closest off-axis aspheric mirror surface and calculate the asphericity; Step 3: Select the processing method based on the fitted off-axis aspheric mirror surface and asphericity; Step 4: Determine the processing tool and speed according to the processing method; Step 5: Determine the rotation speed of the turntable according to the actual diameter of the blank and the diameter of the aspherical surface; Step 6: Determine the step length of the machining tool according to the blank material; Step 7: Determine the processing range of the processing tool according to the actual size of the blank; Step 8: Establish a coordinate system, center and fix the blank according to whether the mirror surface to be processed is off-axis; Step 9: Start processing after confirming that the above steps are correct and the on-site situation is safe.

2. The off-axis aspheric mirror processing technology based on a milling machine according to claim 1 is characterized in that: When calculating the aspheric radius of the off-axis aspheric mirror, it is necessary to pay attention to the concavity and convexity of the open surface, the positive and negative values ​​of the aspheric coefficient K, K>0, the open surface is convex, K<0, the open surface is concave; The vertex curvature radius R calculated for off-axis aspheric mirrors needs to be increased or decreased based on the requirements of the drawing. The smaller the R value, the greater the increase or decrease required, and the larger the R value, the smaller the increase or decrease required.

3. The off-axis aspheric mirror processing technology based on a milling machine according to claim 1 is characterized in that: The closest spherical radius calculated in step 2 should be ensured to be within the range of -0.03 to +0.03; When the calculated asphericity is not within this range, the vertex curvature radius R is readjusted to calculate the radius closest to the spherical surface, and the calculated asphericity is adjusted to be within the range of -0.03 to +0.

03.

4. The off-axis aspheric mirror processing technology based on a milling machine according to claim 1 is characterized in that: Step 4 K9 material, NBK7 material, softer quartz material, etc. choose electroplated diamond tools; For microcrystalline materials, single crystal silicon materials, and harder quartz materials, bronze sintered diamond tools are selected; A resin wheel cutter is used at the end of processing.

5. The off-axis aspheric mirror processing technology based on a milling machine according to claim 1 is characterized in that: Step 5 When starting processing, start with a low-number tool, and then use a high-number tool for subsequent processing. The tool step distance becomes smaller and smaller as the mesh number increases. The step distance is determined according to the number of tools.

6. The off-axis aspheric mirror processing technology based on a milling machine according to claim 1, characterized in that: Step seven The off-axis mirror uses the grating processing method, and the processing range is expanded by about 5%. When the mirror surface to be processed is a convex mirror surface, the tool for processing the convex mirror off-axis mirror must be raised by a vector height (the vector height of the convex mirror).

7. The off-axis aspheric mirror processing technology based on a milling machine according to claim 1 is characterized in that: Step eight According to the required processing mirror surface is an off-axis aspherical mirror surface, the blank is established with a coordinate system, centered and fixed. Equal division: mark the blank into equal parts; Fixing: Use rosin wax to fix the blank on the turntable; Centering: If it is a circular blank, straighten the axis of the blank outward and align it with the tool position so that the two overlap on the same straight line; If it is a rectangular blank, align one side of the blank with the tool position so that the two overlap on the same straight line, and then use a micrometer to find the center; Establish a coordinate system: Set the center found by the micrometer as the coordinate origin and establish a coordinate system before processing.

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