A precision centering processing method for optical lens

Abstract

The present application provides a precision centering processing method for an optical lens, comprising: installing the lens to be processed on an adjustment tool to obtain a centering device, adjusting the position of the centering device so that the centering device focuses on the lens to be processed; driving the adjustment tool to rotate along the main axis, and when it is determined that the rotation directions of the first fork image and the second fork image are opposite, adjusting the horizontal position and vertical position of the lens to be processed so that the rotation directions are in the same direction; adjusting the pitch position and yaw position of the lens to be processed so that the jump circle of the first fork image and the second fork image is minimized; adjusting the horizontal position and vertical position of the lens to be processed so that the size of the jump circle of the first fork image and the second fork image is the same or equivalent; until the radius of the jump circle of the first fork image and the second fork image is less than the set value; grinding the outer circle and end face of the lens to be processed to obtain the target lens. Through the above steps, the precision centering of the lens is achieved, and the linear deviation of the optical lens is reduced.

Description

Technical Field

[0001] The present disclosure generally relates to the field of lens processing technology, and in particular to a precision centering processing method for an optical lens. Background Art

[0002] In the production process of lenses, it is often necessary to center the lenses and then grind their edges;

[0003] For lenses with high precision requirements, such as infrared optical lenses with approximately equal thickness, the center deviation index is difficult to control during the optical processing because the distance between the center of the convex surface and the center of the concave surface is small. With conventional optical centering and edging processing, the minimum linear deviation can only be controlled to 0.02mm, which is low in precision and cannot achieve stable precision control of ≤0.01mm.

[0004] Once the linear quantity of such parts is greater than 0.02mm, during the optical assembly and calibration process, when the double-sided optical centering is performed to an accuracy of ≤2μm, the outer circle runout or end face runout of the lens may reach more than 0.5mm, making it difficult to assemble the lens and its matching optomechanical components and prone to quality problems. Summary of the invention

[0005] In view of the above defects or deficiencies in the prior art, it is desired to provide a precision centering method for an optical lens that can solve the above technical problems.

[0006] The present application provides a precision centering processing method for an optical lens, comprising:

[0007] The lens to be processed is mounted on an adjustment tool, wherein the adjustment tool has a main axis and is mounted on a machine tool so as to be rotatable along the main axis;

[0008] Obtaining a centering device, and adjusting the position of the centering device so that the centering device focuses on the convex focus and the concave focus of the lens to be processed;

[0009] The adjusting fixture is driven to rotate along the main axis, and:

[0010] s31: when it is determined that the rotation directions of the first crosshair image and the second crosshair image are opposite, the horizontal position and the vertical position of the lens to be processed are adjusted so that the rotation directions are in the same direction; the first crosshair image is the crosshair image of the centering device on the focal plane where the convex focus is located, and the second crosshair image is the crosshair image of the centering device on the focal plane where the concave focus is located;

[0011] s32: adjusting the pitch position and the yaw position of the lens to be processed so that the jumping circles of the first fork image and the second fork image are minimized; adjusting the horizontal position and the vertical position of the lens to be processed so that the sizes of the jumping circles of the first fork image and the second fork image are the same or equivalent;

[0012] s33: repeating steps s31 and s32 until the radius of the beating circle of the first crosshair image and the second crosshair image is smaller than a set value;

[0013] The outer circle and the end face of the lens to be processed are ground to obtain a target lens.

[0014] According to the technical solution provided in the embodiment of the present application, the centering device includes a first centering device and a second centering device arranged on both sides of the adjustment tool; the adjustment tool is provided with an optical path avoidance hole along the main axis direction thereof;

[0015] The first centering instrument is used to focus on the convex focus of the lens to be processed and display the first crosshair image; the second centering instrument is used to focus on the concave focus of the lens to be processed and display the second crosshair image.

[0016] According to the technical solution provided in the embodiment of the present application, the centering device includes a third centering device arranged on a side of the lens to be processed away from the adjustment tooling;

[0017] The third centering device is adjustable in horizontal position so that it can focus on the convex focal point of the lens to be processed and display the first crosshair image at different horizontal positions, or focus on the concave focal point of the lens to be processed and display the second crosshair image.

[0018] According to the technical solution provided in the embodiment of the present application, the set value is 2um.

[0019] According to the technical solution provided in the embodiment of the present application, the edge thickness difference allowance Δl of the lens to be processed is calculated by formula (1):

[0020]

[0021] Among them, R 1 is the convex radius of the target lens; R 2 is the concave radius of the target lens; d is the center thickness of the target lens; Φ is the aperture of the target lens; ΔΦ is the lens edge grinding margin; h 1 is the convex sag of the target lens; a is the set ratio.

[0022] According to the technical solution provided in the embodiment of the present application, the set ratio a is 65%-75%.

[0023] According to the technical solution provided in the embodiment of the present application, the lens edge grinding margin ΔΦ of the lens to be processed is 0.5-2mm.

[0024] According to the technical solution provided in the embodiment of the present application, the concave sagittal margin of the lens to be processed is 0.2-0.6mm.

[0025] According to the technical solution provided in the embodiment of the present application, a flange is detachably mounted on the adjustment tool, and the lens to be processed is adhesively mounted on the flange.

[0026] The beneficial effects of the present application are as follows: the present application provides a prerequisite reference environment for adjusting the precise centering of the optical lens by adjusting the skew intersection position of the main axis and the optical axis; by adjusting the pitch position and the yaw position of the lens to be processed so as to minimize the jitter circles of the first fork image and the second fork image; by adjusting the horizontal position and the vertical position of the lens to be processed so as to make the jitter circles of the first fork image and the second fork image the same or equivalent in size, and by multiple iterative operations, the optical axis and the main axis gradually become collinear, thereby achieving precise centering of the lens; and then by grinding the target lens, the linear deviation is reduced and the production quality is improved; in actual operation, the linear deviation can be stably controlled within an accuracy range of less than 0.01 mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0028] Figure 1 A flowchart of a precision centering processing method for an optical lens provided in the present application;

[0029] Figure 2 for Figure 1 The schematic diagram of the double-light path double-sided reflection centering method used in the precision centering processing method is shown;

[0030] Figure 3 for Figure 1 The schematic diagram of single light path double-sided reflection centering is shown in the method of precision centering processing;

[0031] Figure 4 A schematic diagram of a crosshair image 13 and a jumping circle 14 displayed by a centering device;

[0032] Figure 5 is a schematic diagram of the size structure of the target lens;

[0033] Figure 6 is the convex radius R of the target lens 1 With concave radius R 2 Schematic diagram of

[0034] Numbers in the figure:

[0035] 1. Lens to be processed; 11. Convex focus; 12. Concave focus; 13. Crosshair image; 14. Jump circle; 2. Adjustment tool; 21. Flange; 31. First centering device; 32. Second centering device; 33. Third centering device; DETAILED DESCRIPTION

[0036] The present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It is also necessary to explain that, for ease of description, only the parts related to the invention are shown in the accompanying drawings.

[0037] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0038] Please refer to Figure 1 A flowchart of a precision centering method for an optical lens provided in this application includes:

[0039] S1: Mounting the lens 1 to be processed on the adjusting fixture 2, wherein the adjusting fixture 2 has a main axis and is mounted on the machine tool so as to be rotatable along the main axis;

[0040] S2: obtaining a centering device, and adjusting the position of the centering device so that the centering device focuses on the convex focus 11 and the concave focus 12 of the lens 1 to be processed;

[0041] Specifically, the axis of the centering device is colinear with the main axis, and the main axis is parallel to the horizontal direction;

[0042] Specifically, the lens 1 to be processed is an infrared optical lens, for example, an infrared optical lens of approximately equal thickness;

[0043] Specifically, the two end surfaces of the lens 1 to be processed are respectively a convex surface and a concave surface, the convex surface has a convex focus, and the concave surface has a concave focus;

[0044] Specifically, the centering device is a prior art and will not be described in detail here;

[0045] S3: driving the adjusting tool 2 to rotate along the main axis, and:

[0046] s31: when it is determined that the rotation directions of the first crosshair image and the second crosshair image are opposite, the horizontal position and the vertical position of the lens to be processed are adjusted so that the rotation directions are in the same direction; the first crosshair image is the crosshair image of the centering device on the focal plane where the convex focus is located, and the second crosshair image is the crosshair image of the centering device on the focal plane where the concave focus is located;

[0047] Specifically, the horizontal position refers to a position parallel to the horizontal plane and perpendicular to the direction of the main axis; the vertical position refers to a position perpendicular to the horizontal plane.

[0048] Specifically, the crosshair image 13 presented in the definition instrument device and the jumping circle 14 formed by the rotation of the crosshair image 13 are as follows: Figure 4 As shown;

[0049] It is necessary to further explain that the line connecting the convex focus 11 and the concave focus 12 is the optical axis of the lens 1 to be processed; when the first cross-hair image and the second cross-hair image rotate in opposite directions, it means that the eccentric intersection position of the main axis and the optical axis is located between the convex focus 11 and the eccentric focus 12; when the first cross-hair image and the second cross-hair image rotate in the same direction, it means that the eccentric intersection position of the main axis and the optical axis is located on one side of the convex focus 11 and the eccentric focus 12;

[0050] s32: adjusting the pitch position and the yaw position of the lens 1 to be processed so that the jumping circles of the first fork image and the second fork image are minimized; adjusting the horizontal position and the vertical position of the lens 1 to be processed so that the sizes of the jumping circles of the first fork image and the second fork image are the same or equivalent;

[0051] Specifically, the pitch position refers to the position of the lens to be processed 1 swinging along the pitch axis, and the pitch axis is parallel to the horizontal direction and perpendicular to the main axis; the yaw position refers to the position of the lens to be processed swinging along the yaw axis, and the yaw axis is perpendicular to the main axis and the pitch axis;

[0052] It needs further explanation that when the skew intersection position is on one side of the two foci:

[0053] The size of the beating circle of the first crosshair image is used to characterize the distance of the convex focus relative to the main axis; the size of the beating circle of the second crosshair image is used to characterize the distance of the convex focus relative to the main axis;

[0054] That is, the smaller the jump circle is, the smaller the distance between the focus and the main axis is, and the closer the sizes of the two jump circles are, the closer the optical axis and the main axis are to being parallel.

[0055] It can also be seen that step S31 provides a prerequisite reference environment for adjusting the consistency of the optical axis and the main axis;

[0056] At the position adjusted in step S31, the pitch position and the yaw position of the lens to be processed are adjusted in step S2 so that the distance between the two focal points and the main axis is minimized, that is, the optical axis and the main axis tend to be parallel; the horizontal position and the vertical position of the lens to be processed are adjusted again so that the sizes of the jumping circles of the first fork image and the second fork image are the same or equivalent, and at this time, the skew intersection position returns to between the two focal points again;

[0057] s33: repeating steps s31 and s32 until the radius of the beating circle of the first crosshair image and the second crosshair image is smaller than a set value;

[0058] Specifically, after adjusting the position of the lens 1 to be processed, refocusing is required to obtain the first crosshair image and the second crosshair image.

[0059] By repeating steps s31 and s32, the optical axis and the main axis gradually approach collinearity. When it is finally determined that the radius of the jumping circle of the first crosshair image and the second crosshair image is less than the set value, it indicates that the centering process of the lens is completed.

[0060] S4: Grinding the outer circle and end surface of the lens to be processed to obtain a target lens.

[0061] Working principle: The present application provides a prerequisite reference environment for adjusting the precise centering of the optical lens by adjusting the skew intersection position of the main axis and the optical axis; by adjusting the pitch position and the yaw position of the lens to be processed so as to minimize the jump circles of the first fork image and the second fork image; by adjusting the horizontal position and the vertical position of the lens to be processed so as to make the jump circles of the first fork image and the second fork image the same or equivalent in size, and by multiple iterative operations, the optical axis and the main axis gradually become collinear, thereby achieving precise centering of the lens; and then by grinding the target lens, the linear deviation is reduced; in actual operation, the linear deviation can be stably controlled within an accuracy range of less than 0.01mm.

[0062] In some embodiments, the set value is 2 um.

[0063] In some embodiments, a flange 21 is detachably mounted on the adjusting tool 2 , and the lens 1 to be processed is adhesively mounted on the flange 21 .

[0064] Specifically, the flange 21 needs to be designed and prepared according to the shape of the part;

[0065] Specifically, the installation process includes:

[0066] Heating the flange 21, and applying the solid adhesive to the heated flange 21, so that the solid adhesive becomes liquid;

[0067] Visually check the relative positions of the lens to be processed and the flange 21 to make their rotation axes roughly coincide with each other;

[0068] Bond the lens 1 to be processed with the concave surface facing upward to the connecting flange 21;

[0069] After the solid adhesive is solidified, the flange 21 and the adjusting fixture 2 are connected and locked by threading.

[0070] In some embodiments, the adjustment tool 2 is used to achieve: adjusting the horizontal position and the vertical position of the lens 1 to be processed; adjusting the pitch position and the yaw position of the lens 1 to be processed;

[0071] Specifically, the adjustment tool 2 is a four-dimensional adjustment mechanism, which can realize the adjustment of the target part with four degrees of freedom, namely: horizontal movement, vertical movement, pitch movement and yaw movement. This is the existing technology, for example, the 7MML516 four-dimensional adjustment lens holder is selected.

[0072] In some embodiments, Figure 2 As shown, the centering device comprises a first centering device 31 and a second centering device 32 arranged on both sides of the adjusting tool; the adjusting tool 2 is provided with an optical path avoidance hole along the main axis direction thereof;

[0073] The first centering instrument 31 is used to focus on the convex focus 11 of the lens 1 to be processed and display the first crosshair image; the second centering instrument 32 is used to focus on the concave focus 12 of the lens to be processed and display the second crosshair image.

[0074] By providing the first centering instrument 3 and the second centering instrument 32, the first crosshair image and the second crosshair image are respectively obtained by double-light path double-sided reflection; thereby, the lens centering operation is facilitated, which is beneficial to improving work efficiency.

[0075] In some embodiments, Figure 3 As shown, the centering device includes a third centering device 33 arranged on a side of the lens 1 to be processed away from the adjustment tool 2;

[0076] The third centering device 33 is adjustable in horizontal position so that it can focus on the convex focus 11 of the lens 1 to be processed to display the first crosshair image, or focus on the concave focus 12 of the lens 1 to be processed to display the second crosshair image at different horizontal positions.

[0077] Preferably, the third centering device 33 uses an infrared optical material that is transparent in the visible light band, such as multi-spectrum ZnS, CVD ZnSe, etc.

[0078] By setting the third centering device 33, the first and second fork-wire images are obtained by single-light path reflection. In this way, one centering device is set, and the first and second fork-wire images are obtained in sequence by adjusting its position, thereby reducing the cost of the system.

[0079] Example 2

[0080] Based on Example 1, in some embodiments, the edge thickness difference allowance Δl of the lens 1 to be processed is calculated by formula (1):

[0081]

[0082] Among them, Figure 6 As shown, R 1 is the convex radius of the target lens; R 2 is the concave radius of the target lens; d is the center thickness of the target lens; Φ is the aperture of the target lens; ΔΦ is the lens edge grinding margin; h 1 is the convex sag of the target lens; a is the set ratio.

[0083] by Figure 5 Take the size of the target lens as an example, its convex radius R 1 =67.61mm, concave radius R 2 =68.08mm, center thickness d = 5.19mm, diameter Φ = 31.5mm, convex surface height h 1 =1.86mm, a=70%;

[0084] Then: Δl = 0.022mm;

[0085] The edge thickness difference allowance Δl of the lens to be processed must be controlled below 0.022mm. In actual operation, the edge thickness difference of the finished blank is required to be ≤0.02mm after fine grinding. After passing the inspection using a thickness measuring platform with a dial indicator or micrometer, double-sided polishing is performed.

[0086] On the basis of Example 1, this embodiment takes into account that during the fine grinding and polishing process, if the edge thickness difference of the lens is too large, it will also cause excessive outer circle runout or end face runout, resulting in insufficient margin in the centering and edging process. Therefore, the above formula is used to optimize the calculation method of the edge thickness difference allowance Δl for the lens to be processed.

[0087] In some embodiments, the set ratio a is 65%-75%. Preferably, the set ratio a is 70%.

[0088] In some embodiments, the lens edge grinding margin ΔΦ of the lens to be processed is 0.5-2 mm.

[0089] In some embodiments, the concave sagittal margin of the lens to be processed is 0.2-0.6 mm.

[0090] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with (but not limited to) technical features with similar functions disclosed in the present application.

Claims

1. A precision centering method for an optical lens, It is characterized in that include: The lens to be processed is mounted on an adjustment tool, wherein the adjustment tool has a main axis and is mounted on a machine tool so as to be rotatable along the main axis; Obtaining a centering device, and adjusting the position of the centering device so that the centering device focuses on the convex focus and the concave focus of the lens to be processed; The adjusting fixture is driven to rotate along the main axis, and: s31: when it is determined that the rotation directions of the first crosshair image and the second crosshair image are opposite, the horizontal position and the vertical position of the lens to be processed are adjusted so that the rotation directions are in the same direction; the first crosshair image is the crosshair image of the centering device on the focal plane where the convex focus is located, and the second crosshair image is the crosshair image of the centering device on the focal plane where the concave focus is located; s32: adjusting the pitch position and the yaw position of the lens to be processed so that the jumping circles of the first fork image and the second fork image are minimized; adjusting the horizontal position and the vertical position of the lens to be processed so that the sizes of the jumping circles of the first fork image and the second fork image are the same or equivalent; s33: repeating steps s31 and s32 until the radius of the beating circle of the first crosshair image and the second crosshair image is smaller than a set value; Grinding the outer circle and end surface of the lens to be processed to obtain a target lens; The edge thickness difference allowance Δ of the lens to be processed l Calculated by formula (1): (one); in, R 1 is the convex radius of the target lens; R 2 is the concave radius of the target lens; d is the center thickness of the target lens; Φ is the aperture of the target lens; ΔΦ is the lens edge grinding margin; h 1 is the convex sag of the target lens; a is the set ratio; The centering device comprises a first centering device and a second centering device arranged on both sides of the adjusting tool; the adjusting tool is provided with an optical path avoidance hole along the main axis direction thereof; The first centering instrument is used to focus on the convex focus of the lens to be processed and display the first crosshair image; The second centering instrument is used to focus on the concave focal point of the lens to be processed and display the second crosshair image.

2. The method for precision centering of an optical lens according to claim 1, It is characterized in that The centering device may also include a third centering device arranged on a side of the lens to be processed away from the adjustment tooling; The third centering device is adjustable in horizontal position so that it can focus on the convex focal point of the lens to be processed and display the first crosshair image at different horizontal positions, or focus on the concave focal point of the lens to be processed and display the second crosshair image.

3. The method for precision centering of an optical lens according to claim 1, It is characterized in that The setting value is 2 um .

4. The method for precision centering of an optical lens according to claim 1, It is characterized in that The setting ratio a It is 65%-75%.

5. The method for precision centering of an optical lens according to claim 1, It is characterized in that The lens edge grinding margin ΔΦ of the lens to be processed is 0.5-2mm.

6. The method for precision centering of an optical lens according to claim 1, It is characterized in that The concave surface sagittal margin of the lens to be processed is 0.2-0.6 mm.

7. The method for precision centering of an optical lens according to any one of claims 1 to 6, It is characterized in that The adjusting tool is detachably provided with a flange, and the lens to be processed is adhesively mounted on the flange.

Images