Clamping device and method for measuring verticality and coaxiality of lens based on dual-optical-path decentration measuring instrument

Abstract

The invention discloses a clamping device and method for measuring verticality and coaxiality of a lens based on a dual-optical-path decentration measuring instrument. The method comprises the following steps: 1) clamping the lens to be measured on an adjusting platform of the dual-optical-path decentration measuring instrument; 2) adjusting the adjusting platform until the upper surface and the lower surface of the to-be-measured lens respectively form clear reflection images; 3) obtaining an angle error beta between the upper surface and the lower surface of the lens to be measured through a dual-optical-path decentration measuring instrument; (4) the adjusting platform is adjusted until the angle error beta meets the requirement; and 5) measuring the run-out value of the edge dragging surface of the to-be-measured lens as the verticality of the lens by using the dial indicator, and measuring the 1 / 2 run-out value of the cylindrical surface of the to-be-measured lens as the coaxiality of the lens by using the dial indicator. According to the method, a reflection type measurement mode is adopted, perpendicularity and coaxiality detection of lenses of various structural forms can be achieved after one-time clamping, the measurement efficiency is high, the result is accurate, and the consistency is good.

Description

Technical Field

[0001] The present application relates to the field of thermal imaging technology, and in particular to a clamping device and method for measuring the verticality and coaxiality of a lens based on a dual-light path center deviation measuring instrument. Background Art

[0002] During the production process of optical lenses, there are differences between the various dimensional parameters of the actual processed lenses and the design values. When the difference is too large, the lens will be scrapped. In order to avoid unqualified products leaving the factory, the various parameter indicators of the produced lenses need to be tested before leaving the factory to ensure that the lenses meet the design requirements.

[0003] If the lens has a center deviation, the optical axis of the assembled optical system is prone to deviation, which makes the optical system unable to accurately align with the observed target, reducing the imaging performance of the optical system. This problem is particularly prominent in fields such as long-distance temperature measurement of power equipment, video security, on-site rescue, and gun aiming, which require higher optical axis accuracy.

[0004] In addition, for optical systems such as measuring instruments, the deviation of the lens center will also cause off-axis aberrations in the image, causing problems such as field curvature, coma, distortion, etc., making it impossible for the system to accurately capture the geometric shape and size of the object, affecting the measurement accuracy of the instrument.

[0005] Therefore, in the design and production of lenses, it is necessary to strictly control the center deviation of the lens to avoid further error accumulation during the subsequent assembly process. In the existing lens production process, the center deviation of the lens is mainly tested to ensure that the center deviation of the lens to be tested meets the design requirements.

[0006] According to GB / T 7242-2010 "Lens Center Deviation", the so-called lens center deviation is the deviation of the normal line at the centering vertex of the lens optical surface from the reference axis. The indicators that characterize the lens center deviation include: surface inclination angle χ, spherical center difference α and eccentricity difference C.

[0007] In actual production, the deviation of the lens center is often characterized by measuring the edge thickness difference. Since the stylus needs to be in rigid contact with the lens surface when measuring the edge thickness difference, this method is only applicable to the control of the lens center deviation at the blank stage. Otherwise, it is easy to cause wear or damage to the smooth surface of the polished lens.

[0008] In some optical design software (such as CODE V), when evaluating the impact of lens center deviation on the performance of the optical system, the lens needs to be rotated and translated, that is, the lens is intentionally deviated from the ideal position, and then the lens aberration is calculated again to compare the changes in aberrations.

[0009] Rotating a lens means rotating the optical axis of the lens by a small angle relative to the mounting reference plane, which is equivalent to tilting the optical axis of the lens relative to the reference plane, resulting in a verticality error. The verticality error can be characterized by the verticality of the reference plane (usually the edge of the lens) to the optical axis of the lens.

[0010] Translation lens moves the lens by a small amount in the direction perpendicular to the optical axis, which is approximately the coaxiality error between the actual outer cylinder of the lens and the theoretical outer cylinder. It can be characterized by the coaxiality of the outer cylinder of the lens to the optical axis.

[0011] Based on this, some optical designers will use verticality and coaxiality to characterize the center deviation of the lens in the drawings. The advantage is that the measurement results of verticality and coaxiality can be substituted into the rotation and translation parameters of the optical design software to more accurately evaluate and predict the impact of the actual center deviation of the lens on the optical system. It can be seen that the two indicators of lens verticality and coaxiality enrich and improve the indicator system of lens center deviation, providing more options for optical designers to characterize and control lens center deviation. However, the existing measurement methods cannot accurately measure verticality and coaxiality, which affects the effective use of the above-mentioned methods for evaluating lens center deviation.

[0012] Therefore, it is urgent to achieve accurate measurement of lens verticality and coaxiality.

[0013] The control and detection technology of the center deviation of visible light optical elements is mainly a transmission method, which evaluates and controls the center deviation by measuring the spherical center difference and eccentricity difference. For infrared lenses, since commonly used infrared optical materials such as germanium, silicon, and chalcogenide glass are not transparent to visible light, and zinc selenide and infrared-grade zinc sulfide have limited transmittance to visible light, the existing center deviation measuring instruments that must be measured by visible light cannot perform transmission-type center deviation inspection on most infrared optical materials, and the development of center deviation detection technology for infrared lenses is relatively lagging behind.

[0014] The dual-path center deviation measuring instrument uses upper and lower light paths to generate reflection images for the two surfaces of the lens respectively, and evaluates the center deviation of the lens based on the reflection images. This breaks through the limitation that most infrared optical materials are not transparent to visible light, and provides the possibility for the measurement of the center deviation of infrared lenses. The instrument is mainly used for the detection, optical assembly and adjustment of the center deviation of infrared optical material lenses (such as CN202222573192.8, CN202310841981.1). During the assembly process, it can effectively reduce the difficulty of assembly and debugging and improve the efficiency of assembly and adjustment.

[0015] The existing dual-optical path center deviation measuring instrument mainly adjusts the posture of the lens to make the optical axis of the lens coincide with the optical axis of the instrument. The optical axis of a single lens is the line connecting the centers of the two surfaces. Theoretically, when the reflected images of the two surfaces of the lens completely coincide with the cross scale, it means that the line connecting the centers of the two surfaces of the lens (i.e., the optical axis) completely coincides with the optical axis of the measuring instrument. At this time, the runout of the edge surface and the outer cylinder of the lens are measured respectively. According to the previous description, the verticality and coaxiality errors of the lens to be measured with the optical axis as the reference are obtained.

[0016] Of course, due to the existence of errors, it is impossible to completely adjust the reflected images of the two surfaces of the lens to be measured to coincide with the cross scale. The only way is to control the error to a sufficiently small value as much as possible. This is a major source of measurement error in this method.

[0017] In addition, the coaxiality error obtained by this method includes the roundness error of the lens being measured. If the roundness error of the lens itself is too large, it will seriously affect the coaxiality measurement result of the lens. Generally speaking, according to measurement theory, in order to ensure the validity of the measurement result, the roundness error of the lens to be measured should be at least less than one-third of the coaxiality requirement.

[0018] The information disclosed in the background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0019] In response to the above technical problems, the present application provides a clamping device and method for measuring the verticality and coaxiality of a lens based on a dual-optical path center deviation measuring instrument. The method is suitable for simultaneously measuring the verticality and coaxiality of lenses of various shapes and structures through a dual-optical path center deviation measuring instrument, and has high measurement efficiency, accurate measurement results and good repeatability.

[0020] The present application provides a method for measuring the verticality and coaxiality of a lens based on a dual-optical path center deviation measuring instrument, comprising the following steps:

[0021] 1) Clamp the lens to be tested on the adjustment platform of the dual-optical path center deviation measuring instrument and expose the cylindrical surface of the lens to be tested. The height of the cylindrical surface exposed from the top surface of the clamping device must be greater than 1mm;

[0022] 2) After adjusting the adjustment platform until the upper and lower surfaces of the lens to be tested form clear reflection images, a flat crystal is placed on the dragging surface of the lens to be tested and the lens of the upper optical path is removed, and the adjustment platform (41) is adjusted until the angle error of the upper surface of the display interface is within 2";

[0023] 3) Remove the flat crystal and reinstall the lens into the upper optical path, input the curvature radius of the upper and lower surfaces of the lens to be tested and the lens parameters, obtain the angle error β of the upper and lower surfaces of the lens to be tested through the dual optical path center deviation measuring instrument, adjust the adjustment platform (41) until the angle error β meets the requirement, if not, return to step 2);

[0024] 4) Use a micrometer to measure the runout value of the drag edge surface of the lens to be tested as the verticality of the lens, and use a micrometer to measure the 1 / 2 runout value of the cylindrical surface of the lens to be tested as the coaxiality of the lens.

[0025] Preferably, the requirement for the angle error β is:

[0026] 1) When the radius of curvature of the lens to be measured is ≤15mm, the angle error β is required to be ≤15";

[0027] 2) When the radius of curvature of the lens to be tested is 15-40mm or 40mm, the angle error β is required to be ≤10";

[0028] 3) When the radius of curvature of the lens to be measured is 40-100mm or 100mm, the angle error β is required to be ≤5";

[0029] 4) When the radius of curvature of the lens to be measured is 100-500mm or 500mm, the angle error β is required to be ≤2";

[0030] 5) When the radius of curvature of the lens to be measured is greater than 500, the angle error β is required to be ≤ 1".

[0031] Preferably, the edge thickness of the lens to be tested must be greater than or equal to 1.5 mm;

[0032] Preferably, the lens to be tested is an axisymmetric rotation lens.

[0033] Preferably, when the aperture of the flat crystal is ≤100 mm, the aperture N of the flat crystal surface is ≤3, the local aperture △N is ≤1, and the local aperture △N within the area within 50 mm of the center of the flat crystal is ≤0.5;

[0034] Preferably, when the aperture of the flat crystal is greater than 100 mm, the flat crystal surface shape requires that the aperture N is less than or equal to 4, the local aperture △N is less than or equal to 1, and the local aperture △N within the area within 50 mm of the center of the flat crystal is less than or equal to 0.5;

[0035] Preferably, the aperture of the flat crystal is larger than the outer diameter of the lens to be tested;

[0036] Preferably, the diameter of the flat crystal ranges from 40 to 200 mm;

[0037] Preferably, the thickness of the flat crystal is 4 to 14 mm, and the value is selected to satisfy the diameter-to-thickness ratio of the flat crystal is 10 to 15:1;

[0038] Preferably, the material used for the flat crystal is K9 glass or a visible light-transmitting material having physical and chemical properties superior to K9 glass;

[0039] Preferably, the smoothness of the flat crystal is: Grade V, and the parallelism difference between the two surfaces is ≤5".

[0040] Another aspect of the present application further provides a clamping device for the above method, comprising:

[0041] Elastic clamp seat, elastic clamp cap;

[0042] The elastic fixture seat is disassembled and arranged on the adjustment platform of the dual-optical path center deviation measuring instrument; a through hole is arranged in the elastic fixture seat, and the light output end of the lower optical path of the dual-optical path center deviation measuring instrument is arranged opposite to one end of the through hole of the elastic fixture seat;

[0043] The lens to be tested is placed on the step of the elastic fixture seat boss (12);

[0044] The elastic clamp cap is arranged on the elastic clamp seat and is detachably connected to the elastic clamp seat; the inner supporting surface of the top of the elastic clamp seat is in clamping contact with the cylindrical surface of the lens to be tested; and the inner step (114) of the top of the elastic clamp seat is in contact with the lower convex edge of the lens to be tested.

[0045] Preferably, the elastic fixture seat comprises: a base, a pedestal, and a boss; the base is arranged in the central area of ​​the base, and the boss is arranged on the base; the through hole passes through the base, the pedestal, and the boss; the lens to be tested is placed on the boss;

[0046] Preferably, a support surface and a step (114) are provided on the upper inner wall of the through hole in the boss; the clearance between the inner wall support surface of the boss through hole above the base and the outer cylindrical surface of the lens to be tested is 0.05-0.15 mm;

[0047] Preferably, the outer cylindrical surface of the lens to be tested is exposed more than 1 mm from the top surface of the boss;

[0048] Preferably, the total height of the elastic clamp seat is 40-55 mm; the thickness of the base is 10-20 mm;

[0049] Preferably, the inner diameter of the step (114) is larger than the effective aperture of the lens to be tested;

[0050] Preferably, a supporting surface and a step are provided on the upper portion of the boss, the supporting surface is in contact with the outer cylindrical surface of the lens to be tested, and the lower convex surface is in contact with the step.

[0051] Preferably, a plurality of grooves are evenly distributed on the top of the circumference of the boss; the groove width is 1 to 2.5 mm, and the groove depth is 20 to 25 mm;

[0052] Preferably, the number of grooves is 2E; when the diameter of the lens to be tested is ≤30 mm, E=3; when the diameter of the lens to be tested is >30 mm, E=4; and when the diameter of the lens to be tested increases by 20 mm, E increases by 1.

[0053] Preferably, the bottom surface roughness of the base is Ra1.6, and the surface accuracy is better than 0.002 mm.

[0054] Preferably, the through hole arranged at the center of the base has a hole diameter of Φ15 to 30 mm.

[0055] Preferably, a threaded structure is provided at the lower part of the inner wall of the elastic clamp cap, which is threadedly connected with the threaded structure provided on the outer wall of the base; the conical surface of the upper inner wall of the elastic clamp cap is pressed against the conical surface of the outer wall of the upper boss of the elastic clamp; the top supporting surface of the boss is in contact with the cylindrical surface of the lens to be tested;

[0056] Preferably, the height of the elastic clamp cap should match that of the elastic clamp seat;

[0057] Preferably, the thread structure of the inner wall of the elastic clamp cap should match the thread structure of the outer wall of the elastic clamp seat base;

[0058] Preferably, the conical surface of the inner wall of the elastic clamp cap should match the conical surface of the outer wall of the upper boss of the elastic clamp seat.

[0059] The beneficial effects of this application include:

[0060] 1) The detection method for measuring the verticality and coaxiality of the lens based on the dual-optical path center deviation measuring instrument provided in this application can realize the verticality and coaxiality detection of lenses of various structural forms after one clamping, with high efficiency, good result consistency, and verified by production practice. At the same time, this method enriches and improves the detection system of lens center deviation, and provides more options for optical designers to characterize and control lens center deviation. When the optical designer uses verticality and coaxiality to mark the center deviation in the drawing, the measurement result is obtained by this method, and then the actual measurement results of the verticality and coaxiality are substituted back into the optical design software to quantitatively predict and evaluate the impact of the lens center deviation on the optical system, which is beneficial to improve the assembly quality of the infrared optical system. After detection by this method, the factory delivery of unqualified products can also be avoided.

[0061] 2) The clamping device for measuring the verticality and coaxiality of the lens based on the dual-optical path center deviation measuring instrument provided in the present application can avoid damage to the lens and protect the lens while clamping the lens, while ensuring the exposure of the cylindrical surface of the lens and ensuring the normal measurement. During the measurement process, the lens is clamped reliably without displacement or rotation, which can improve the accuracy of the measurement results. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 A schematic diagram of the principle of measuring perpendicularity and coaxiality in at least one embodiment provided in the present application;

[0063] Figure 2 A schematic diagram of a lens to be tested in at least one embodiment provided in the present application;

[0064] Figure 3 A schematic cross-sectional front view of an elastic clamp seat in at least one embodiment provided in the present application;

[0065] Figure 4 A schematic cross-sectional front view of an elastic clamp cap in at least one embodiment provided in the present application;

[0066] Figure 5 A schematic diagram of a flat wafer in at least one embodiment provided in the present application;

[0067] Figure 6 A schematic cross-sectional view of a clamping device for measuring the verticality and coaxiality of a lens based on a dual-light path center deviation measuring instrument in at least one embodiment provided in the present application;

[0068] Figure 7 An exploded schematic diagram of a clamping device for measuring the verticality and coaxiality of a lens based on a dual-light path center deviation measuring instrument in at least one embodiment provided in the present application;

[0069] Figure 8 A schematic flow chart of a method for measuring the verticality and coaxiality of a lens using a dual-light path center deviation measuring instrument in at least one embodiment of the present application;

[0070] Legend:

[0071] Elastic clamp seat 1, base 11, slot 111, boss 12, support surface 112, base 113, step 114, elastic clamp cap 2, lens to be tested 3, dragging surface 31, flat crystal 4, screw 5, adjustment platform 41, upper light path 42, lower light path 43, horizontal adjustment knob 45, vertical adjustment knob 44. DETAILED DESCRIPTION

[0072] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0073] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. 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.

[0074] The technical means that are not described in detail in this application and are not used to solve the technical problems of this application are all set according to the common knowledge in the field, and can be implemented in a variety of common knowledge settings.

[0075] See also Figures 1 to 7 The present application provides a clamping device for measuring the verticality and coaxiality of a lens based on a dual-optical path center deviation measuring instrument. The elastic clamp comprises: an elastic clamp seat 1, an elastic clamp cap 2, and the elastic clamp seat 1 is fixed on an adjustment platform 41 of the dual-optical path center deviation measuring instrument by screws 5; a lens 3 to be measured is placed on the elastic clamp seat 1; the lower thread of the elastic clamp cap 2 is threadedly connected with the elastic clamp seat 1, and a conical surface is provided on the upper inner wall of the elastic clamp cap, which is crimped with the conical surface of the outer wall of the upper boss of the elastic clamp seat to fix the lens 3 to be measured on the elastic clamp seat 1.

[0076] The edge surface 31 of the lens 3 to be tested faces upward, and the lens 3 to be tested is placed on the elastic clamp seat 1 so that the top support surface 112 of the boss 12 contacts the cylindrical surface of the lens 3 to be tested, and the lower convex surface contacts the step 114, and the cylindrical surface of the lens 3 to be tested is exposed. The height of the cylindrical surface exposed from the top surface of the clamping device must be greater than 1 mm. After tightening the elastic clamp cap 2, the elastic clamp seat 1 shrinks inward, the boss 12 clamps the cylindrical surface of the lens 3 to be tested, the lens is removed, and the flat crystal 4 is placed on the edge surface 31 of the lens 3 to be tested to adjust the angular error in the vertical direction. The lens is installed, the flat crystal is removed, and the angular error in the horizontal direction is adjusted until the angle meets the requirements. The runout value of the edge surface of the lens to be tested is measured using a micrometer as the verticality of the lens, and the 1 / 2 runout value of the cylindrical surface of the lens to be tested is measured using a micrometer as the coaxiality of the lens.

[0077] The clamp can reliably clamp the lens 3 to be tested, and the test is safe and reliable, while accurate verticality and coaxiality can be obtained.

[0078] In a specific embodiment, the dual-optical path center deviation measuring instrument used includes: an adjustment platform 41, an upper optical path 42, a lower optical path 43, a horizontal adjustment knob 45, and a vertical adjustment knob 44; a vertical adjustment knob 44 and a horizontal adjustment knob 45 are set at the bottom of the adjustment platform 41, and the vertical adjustment knob 44 is used to adjust the inclination of the adjustment platform 41; the horizontal adjustment knob 45 is used to adjust the horizontal translation of the adjustment platform 41.

[0079] In a specific embodiment, the elastic clamp seat 1 comprises: a base 113, a base 11, a boss 12, a step 114, and a slot 111; the base 11 is arranged in the middle of the base 113, and the boss 12 is arranged on the upper part of the base 11; the base 113 and the base 11 are provided with a through hole penetrating the base 113, the base 11, and the boss 12 along the central axis of the elastic clamp seat 1, so as to clamp the lens (3) to be tested and the test light to pass through. A threaded structure is arranged on the outer wall of the base 11. A plurality of slots 111 are evenly distributed on the top of the circumference of the boss 12, and a support surface 112 and a step 114 are arranged in the through hole of the boss 12. The top support surface 112 of the boss 12 contacts the cylindrical surface of the lens 3 to be tested, and the top inner step 114 of the elastic clamp seat 1 contacts the lower convex edge of the lens 3 to be tested.

[0080] In a specific embodiment, a conical surface is provided on the outer side wall of the upper portion of the boss 12 , so that the elastic clamp cap 2 can clamp and squeeze the conical surface of the upper portion of the boss 12 to apply a clamping force to the lens 3 to be tested.

[0081] In a specific embodiment, a threaded structure is provided at the lower portion of the inner wall of the elastic clamp cap 2 to be threadedly connected to the outer wall of the base 11 of the elastic clamp seat.

[0082] In a specific embodiment, a support surface 112 and a step 114 are provided on the upper inner wall of the through hole provided in the boss 12. The clearance between the support surface 112 of the inner wall of the through hole of the boss 12 above the base 11 and the outer cylindrical surface of the lens 3 to be tested is 0.05-0.15 mm. The width of the step 114 is 0.5-1.5 mm, which needs to be determined according to the effective aperture of the lens 3 to be tested. The height of the step 114 is 0.5-2.5 mm, which needs to be determined according to the arc height of the lens to be tested. The inner diameter of the step 114 is larger than the effective aperture of the lens 3 to be tested, so as to ensure that the inner surface quality of the effective aperture of the lens 3 to be tested is not damaged. According to this arrangement, even if the surface of the lens 3 to be tested is accidentally scratched during operation, it can be ensured that the scratch is outside the effective aperture of the lens 3 to be tested, and the normal use of the lens 3 to be tested is not affected.

[0083] In a specific embodiment, when the edge surface 31 of the lens 3 to be tested is placed on the elastic clamp seat 1 with the edge surface 31 facing upward, the outer circumference of the lens 3 to be tested is exposed by more than 1 mm from the top surface of the boss 12. This facilitates operation and avoids the problem that the micrometer contacts the chamfer of the lens 3 to be tested when measuring coaxiality, resulting in inaccurate measurement results, due to the outer circumference of the lens 3 to be tested being too slightly higher than the elastic clamp seat 1.

[0084] In a specific embodiment, a plurality of slots 111 are evenly distributed on the top of the circumference of the boss 12; the slot width of the slot 111 is 1 to 2.5 mm, and the length of the slot 111 is 20 to 25 mm; the slot width and slot depth of the slot 111 increase with the increase of the diameter of the lens 3 to be tested. This is to achieve reliable support of the lens 3 to be tested by the boss 12. According to this setting, the elasticity of the elastic clamp can be enhanced, and the lens 3 to be tested can be clamped easily. The slots 111 can ensure that after the elastic clamp seat 1 and the elastic clamp cap 2 are assembled, the top of the elastic clamp seat 1 contracts inward to generate the necessary clamping force for the lens 3 to be tested.

[0085] In a specific embodiment, the number of the slots 111 is 2E (E=3, 4, 5, ...). For example, when the diameter of the lens 3 to be tested is ≤30mm, E=3; when the diameter of the lens 3 to be tested is >30mm, E=4; for every 20mm increase in diameter, E increases by 1. For example, when the diameter of the lens 3 to be tested is 50mm, E=5; when the diameter of the lens 3 to be tested is 70mm, E=6; and so on. If the increase in the diameter of the lens 3 to be tested is less than 20, the value of the next level is taken, for example, when the diameter of the lens 3 to be tested is 45mm, E is 4.

[0086] The boss 12 of the elastic clamp seat 1 is provided with a slot 111. When the elastic clamp cap 2 is tightened, the slot 111 is squeezed by the conical surface of the elastic clamp cap 2, and the slot width becomes narrower, thereby clamping the lens 3 to be tested. In a specific embodiment, the total height of the elastic clamp seat 1 is 40 to 55 mm, and as the diameter of the lens 3 to be tested increases, the slot depth increases accordingly to maintain the elasticity of the elastic clamp; the thickness of the base 113 of the elastic clamp seat 1 is 10 to 20 mm. Similarly, as the diameter of the lens 3 to be tested increases, the thickness of the base 113 of the elastic clamp seat 1 increases accordingly to ensure the overall strength and stability of the elastic clamp.

[0087] In a specific embodiment, the inner diameter of the step 114 is larger than the effective aperture of the lens 3 to be tested, so as to ensure the surface quality of the effective aperture of the lens 3 to be tested and avoid damage in this area.

[0088] In a specific embodiment, the bottom surface of the elastic clamp base 113 is ground so that the bottom surface roughness of the base 113 is Ra1.6, the surface accuracy is better than 0.002mm, and the surface shape is similar to the characteristics of a concave spherical surface. The purpose of fine grinding the bottom surface of the elastic clamp base 113 is not only to ensure that the elastic clamp can be firmly adsorbed on the vacuum suction cup during fine repair of the elastic clamp, but also to ensure that the elastic clamp seat 1 can better fit with the adjustment platform 41 of the center deviation measuring instrument during detection. After being fixed with screws 5, the elastic clamp is evenly stressed as a whole, thereby reducing measurement errors.

[0089] In a specific embodiment, the step 114 of the elastic clamp seat 1 contacts the convex edge of the lens 3 to be tested, and a 45° bevel is formed at the point where the step of the elastic clamp seat contacts the lens. The residual burrs when the step 114 is finely trimmed can be effectively removed, and the surface of the lens 3 to be tested can be effectively prevented from being scratched when the lens 3 to be tested is clamped.

[0090] In a specific embodiment, the aperture Φ of the through hole through the base 113 is 15-30 mm, and the through hole can be provided to allow the light focused by the lower optical path 43 to pass through the through hole and illuminate the surface of the lens 3 to be tested. The light source of the lower optical path 43 is converted into focused light by the parallel light of the autocollimator, and the focused light can be focused on the spherical center of the surface of the lens 3 to be tested after passing through the through hole. The reflected image of the spherical center of the lower surface passes through the central through hole of the elastic fixture and is processed by the lower optical path 43 to become a cross image, thereby realizing detection.

[0091] In a specific embodiment, the bottom surface of the ground base 113 is used as a reference, and a high-precision CNC lathe (when conditions permit, a single-point diamond lathe is recommended) is used to complete the finishing of the inner hole, the step 114, the 45° chamfer and the taper surface at one time, ensuring that the inner hole diameter and the distance from the edge to the step 114 meet the above requirements.

[0092] A high-precision CNC lathe is used to complete the finishing of the inner hole, step 114, 45° chamfer and cone surface at one time. Ensure that the clearance between the inner wall support surface 112 of the through hole of the boss 12 above the base 11 and the outer cylindrical surface of the lens 3 to be tested is 0.05-0.15mm, the width of the step 114 is 0.5-1.5mm, which needs to be determined according to the effective aperture of the lens 3 to be tested; the height of the step 114 is 0.5-2.5mm, which needs to be determined by the arc height of the lens to be tested; the inner diameter of the step 114 is larger than the effective aperture of the lens 3 to be tested, so as to ensure that the inner surface quality of the effective aperture of the lens 3 to be tested is not damaged. Fine-tuning the elastic clamp seat 1 can effectively improve the accuracy of the elastic clamp, reduce the difficulty of adjustment, improve the detection efficiency and the accuracy of the measurement results, and reduce the measurement error.

[0093] In a specific embodiment, a plurality of countersunk screw holes are provided on the base 113, and screws 5 are used to connect with the mounting holes of the measuring instrument adjustment platform 41. The screws 5 used are M4. The M4 countersunk screw holes are drilled on the base of the elastic clamp seat 1 in order not to limit the length of the screws. In principle, shorter screws are used to ensure that the elastic clamp can be fixed well, which can effectively save the clamping time and improve the detection efficiency.

[0094] In a specific embodiment, the elastic clamp cap 2 is connected to the elastic clamp seat 1 through a thread, and its thread, cone surface and height should match the elastic clamp seat 1, which can ensure uniform force when clamping the lens 3 to be tested, and effectively reduce the risk of hidden damage due to uneven force for some special materials such as fluoride, chalcogenide glass, etc.

[0095] In a specific embodiment, the matching conical surfaces and connecting threads of the elastic clamp seat 1 and the elastic clamp cap 2 need to be ground with diamond to ensure sufficient and good contact. When in use, lubricating oil can be applied to the conical surfaces and threads to ensure smooth operation without jamming when tightening the elastic clamp cap 2.

[0096] Grinding the conical surface and connecting threads of the elastic clamp seat 1 and the elastic clamp cap 2, applying lubricating oil and polishing the fitting parts can effectively enhance the fit between the elastic clamp seat 1 and the elastic clamp cap 2, remove burrs, and avoid the elastic clamp seat 1 and the elastic clamp cap 2 from getting stuck when the lens 3 to be tested is clamped under force.

[0097] In a specific embodiment, the outer wall of the base of the elastic clamp seat 1 and the outer wall of the elastic clamp cap 2 are provided with knurling to increase friction and facilitate operation. The friction can be increased when clamping the lens 3 to be tested, and the lens 3 to be tested can be clamped more easily, thereby improving the clamping efficiency.

[0098] In a specific embodiment, the aperture of the flat crystal 4 is larger than the outer diameter of the lens 3 to be tested, the aperture of the flat crystal 4 ranges from 40 to 200 mm, the thickness of the flat crystal 4 ranges from 4 to 14 mm, and the value meets the requirement of diameter-to-thickness ratio (diameter: thickness) = 10 to 15:1.

[0099] In a specific embodiment, the material used for the flat crystal 4 is K9 glass or a visible light-transmitting material with physical and chemical properties better than K9 glass; the smoothness of the flat crystal 4 is: Grade V, and the parallelism difference between the two surfaces is ≤5".

[0100] In a specific embodiment, when the aperture of the flat crystal 4 is ≤100 mm, the aperture N of the flat crystal 4 surface is ≤3, the local aperture △N is ≤1, and the local aperture △N in the area within 50 mm of the center of the flat crystal 4 is ≤0.5;

[0101] When the aperture of the flat crystal 4 is greater than 100mm, the surface shape of the flat crystal 4 requires aperture N≤4, local aperture △N≤1, and the local aperture △N≤0.5 within the central 50mm of the flat crystal 4. The aperture of the flat crystal 4 is larger than the outer diameter of the lens 3 to be tested. Setting the area within the central 50mm of the flat crystal 4 in this way can improve the accuracy of the test results.

[0102] The flat crystal 4 is controlled by the above technical indicators to ensure that the reflected images generated by the upper and lower surfaces of the flat crystal 4 are completely overlapped, so that a clear, fine and bright cross image is obtained, the measurement error is small, and the adjustment speed is improved.

[0103] In a specific embodiment, the micrometer used to measure the runout of the drag surface 31 and the outer cylinder of the lens 3 to be tested should have a measurement accuracy of no less than 1 um.

[0104] In a specific embodiment, the elastic clamp cap 2 includes: a cylinder; a threaded structure is arranged on the inner side wall of the lower part of the cylinder, and the threaded structure is threadedly connected with the threaded structure of the outer side wall of the base 11 of the elastic clamp seat 1. A through hole is arranged inside the cylinder, and the conical surface of the inner side wall of the upper part of the cylinder is pressed against the conical surface area of ​​the boss 12 of the elastic clamp seat to fix the lens 3 to be tested.

[0105] See also Figure 8 Another aspect of the present application further provides a method for detecting the verticality and coaxiality of a lens based on a dual-light path center deviation measuring instrument, comprising the following steps:

[0106] Step S1: According to the structural parameters (aperture, curvature radius of two surfaces) of the lens 3 to be tested, select and install the lenses of the upper optical path 42 and the lower optical path 43 that match the lens 3 to be tested; the specific selection rules are set according to the conventional requirements of the dual optical path center deviation measuring instrument, which will not be repeated here.

[0107] Step S2: Clean the lens to be tested 3, the flat crystal 4, the elastic clamp seat 1, the elastic clamp cap 2 and the screw 5;

[0108] Step S3: Apply a small amount of lubricating oil to the conical surface and threads of the elastic clamp seat 1. The amount is based on the lubricating oil not flowing. Excess lubricating oil can be wiped off with a paper towel.

[0109] Step S4: fixing the base 113 of the elastic clamp seat 1 on the adjustment platform 41 of the dual-light path center deviation measuring instrument with screws 5;

[0110] Step S5: Screw the elastic clamp cap 2 onto the elastic clamp seat 1 until the elastic clamp seat 1 does not deform;

[0111] Step S6: Wearing latex gloves, place the concave surface of the lens 3 to be tested upward, align it with the inner hole of the elastic clamp, and slowly place the lens 3 to be tested vertically downward on the step 114 of the elastic clamp seat 1 to ensure that the lens 3 to be tested is in full contact with the supporting surface 112 and the step 114 of the elastic clamp seat 1. During the placement process, it is forbidden to rotate the lens 3 to avoid scratching the lower surface of the lens 3 to be tested.

[0112] Step S7: Rotate the elastic clamp cap 2 and tighten the elastic clamp (a toothpick can be used to pry the lens 3 to determine whether the lens 3 is clamped), so as to clamp the lens 3 and ensure that the cylindrical surface of the lens 3 is exposed after clamping. The height of the cylindrical surface exposed from the top surface of the clamping device must be greater than 1 mm.

[0113] Step S8: Move the upper optical path 42 and the lower optical path 43 of the measuring instrument respectively, find the reflected images of the upper and lower surfaces of the lens 3 to be measured, adjust the light source to make the reflected image moderate in brightness, and fine-tune the distance between the lens of the upper optical path 42 and the lower optical path 43 and the lens 3 to be measured to form a clear reflected image;

[0114] Step S9: Place the flat crystal 4 on the edge surface 31 of the lens 3 to be tested, remove the lens of the upper optical path 42, adjust the light source until a clear cross cursor appears on the display interface, rotate the adjustment platform 41, and adjust the vertical adjustment knob 44 on the adjustment platform 41 until the angle error of the display interface is within 2";

[0115] Step S10: remove the flat crystal 4, reinstall the lens into the upper optical path 42, input the curvature radius of the upper and lower surfaces of the lens 3 to be tested and the lens parameters, adjust the horizontal adjustment knob 45 of the adjustment platform 41, and obtain the angular error β of the upper and lower surfaces of the lens 3 to be tested through the dual optical path center deviation measuring instrument;

[0116] If the angle error β does not meet the requirement, the vertical adjustment knob 44 and the horizontal adjustment knob 45 need to be adjusted until the angle β meets the requirement. The value of the angle β meets the requirements of Table 1.

[0117] Table 1 Angle error β angle value range

[0118] Radius of curvature of the lens to be measured (unit: mm β angle ≤(unit:") ≤15 15 15~40(inclusive) 10 40~100(inclusive) 5 100~500(inclusive) 2 ＞500 1

[0119] Step S11: contact the micrometer probe with the edge surface 31 of the lens 3 to be tested, rotate the adjustment platform 41, observe and record the numerical variation range of the edge surface 31, and obtain the runout value of the edge surface 31, which is the verticality of the lens 3 to be tested; contact the micrometer probe with the cylindrical surface of the lens 3 to be tested, rotate the adjustment platform 41, observe and record the numerical variation range of the cylindrical surface, and obtain the outer circle runout value, and half of the outer circle runout value is the coaxiality of the lens 3 to be tested.

[0120] The run-out value in this application refers to the difference obtained by subtracting the minimum value from the maximum value among the values ​​displayed on the micrometer during the measurement process.

[0121] Step S12: Repeat step 11, measure the verticality and coaxiality of the lens 3 to be tested at least three times, and calculate the average values ​​of the verticality and coaxiality. The results are the verticality and coaxiality of the lens 3 to be tested, and record the measurement results.

[0122] Step S13: Loosen the elastic clamp cap 2, clamp the exposed part of the lens 3 to be tested with fingers, slowly take out the lens 3 to be tested vertically upwards, put it into a clean and dry container, and the measurement is finished.

[0123] This method uses the optical axis as the reference to unify the measurement reference with the design reference and the assembly reference, thereby obtaining accurate verticality and coaxiality test results of the lens 3 to be tested. This method not only enriches and improves the index system of lens center deviation, but also provides more options for optical designers to characterize and control lens center deviation. It also allows optical designers to substitute the actual measurement results of verticality and coaxiality into the optical design software, and quantitatively predict and evaluate the influence of lens center deviation on the optical system, which is conducive to improving the assembly quality of infrared optical systems.

[0124] In a specific embodiment, if the same lens 3 to be tested needs to be measured after the test in step S13 is completed according to the test requirements, the lens 3 to be tested only needs to be re-inserted and the operation can be performed according to steps 5 to 13.

[0125] In a specific embodiment, after the measurement is completed, the lens 3 to be measured is removed and placed in a container in a designated area, and the entire set of clamping devices is removed and stored in a dry and clean environment for later use.

[0126] In a specific embodiment, when the edge thickness of the lens 3 to be tested is less than 1.5 mm, only the verticality can be tested, but the coaxiality cannot be tested.

[0127] In a specific embodiment, the lens 3 to be measured is a lens made of chalcogenide glass. Due to the particularity of the material, it is easy to be scratched. A micrometer with a ruby ​​head is used for measurement.

[0128] In a specific embodiment, the detection method is applicable to the accurate detection of verticality and coaxiality of lenses in various structural forms.

[0129] In a specific embodiment, when the lens 3 to be tested is a double convex lens or a plano-convex lens, only the coaxiality of the lens can be tested, but the verticality cannot be tested.

[0130] Example

[0131] In this embodiment, the lens 3 to be measured is a germanium infrared lens with a diameter of Φ48 mm, a center thickness of 7 mm, an edge thickness of 3.87 mm, and an effective aperture D 01＝ 44.6 / D 01＝ 37.4mm, the specific size and structure are as follows Figure 2 The convex surface R1 of the lens 3 to be measured has a curvature radius of R70.9mm and an aspheric surface, and the other surface is a concave surface R2 with a curvature radius of R75.47mm. The requirements for verticality and coaxiality are: ⊥=0.02mm, ◎=0.03mm.

[0132] According to the material, shape and effective aperture of the lens, it is calculated that the width of the step of the elastic clamp seat 1 is 1mm and the depth is 2.5mm. At this time, the outer circle of the lens 3 to be measured is 2.15mm higher than the outer circle of the elastic clamp. The elastic clamp boss 12 is grooved, and the width of the groove is 2mm and the depth is 20mm. The number of grooves is 8 (evenly distributed); the thickness of the elastic clamp base is 8mm; the height of the elastic clamp base is 46mm. According to the lens aperture of 48mm, the selected flat crystal 4 has an aperture of Ф60mm and a thickness of 6mm, which is the best.

[0133] The elastic clamp seat 1 is obtained according to the design result, such as Figure 3 The clamping device includes: an elastic clamp seat 1 as shown Figure 3 , elastic clamp cap 2 (see Figure 4 ), flat crystal 4 and screw 5 (see Figure 5 ), a three-dimensional schematic diagram of the clamping device (see Figure 6 ).

[0134] In order to measure the verticality and coaxiality during the measurement process, a clamping device with the above structure is used. The assembled structure is shown in Figure 6, a clamping device (elastic clamp) that has been ground and refined to protect the lens 3 to be measured and improve the fit between the elastic clamp seat 1 and the elastic clamp cap 2. Use M4 screws 5 to fix the elastic clamp on the adjustment platform 41, and let the elastic clamp seat 1 and the elastic clamp cap 2 be in a loose state; clamp the outer circle of the lens 3 to be measured with both hands, align the elastic clamp, and slowly put the lens 3 to be measured into the elastic clamp vertically downward, ensuring that the top inner support surface 112 of the lens 3 to be measured and the elastic clamp seat 1 is in contact with the cylindrical surface of the lens to be measured, and the step 114 is in contact with the edge of the lower convex surface of the lens 3 to be measured. Rotate the elastic clamp cap 2 to tighten the elastic clamp. When tightening the elastic clamp, be careful to prevent the lens 3 to be measured from rotating, and finally clamp the outer circle of the lens 3 to be measured. Place a Ф60 flat crystal 4 on the drag edge surface 31 of the lens to be measured, and adjust the vertical tilt of the lens 3 to be measured. Remove the flat crystal 4, reinstall the lens into the upper optical path 42, input the curvature radius of the upper and lower surfaces of the lens 3 to be tested and the lens parameters, and obtain the angular error β≤5" of the upper and lower surfaces of the lens 3 to be tested through the dual optical path center deviation measuring instrument. Put the micrometer probe in contact with the edge surface 31 of the lens 3 to be tested, rotate the adjustment platform 41, observe the value variation range of the edge surface 31 recorded, and obtain the runout value of the edge surface 31, which is the verticality of the lens 3 to be tested; put the micrometer probe in contact with the cylindrical surface of the lens 3 to be tested Contact, rotate and adjust the platform 41, observe and record the numerical variation range of the cylindrical surface, and obtain the outer circle runout value. Half of the outer circle runout value is the coaxiality of the lens 3 to be tested. Measure the verticality and coaxiality of the lens 3 to be tested at least 3 times, and calculate the average value of the verticality and coaxiality. The result is the verticality and coaxiality of the lens 3 to be tested, and record the measurement results. The measurement results after verification by the flat crystal 4 have high repeatability and accuracy. The results of 10 repeatability measurements of verticality and coaxiality are shown in the following table:

[0135] Table 2 Perpendicularity and coaxiality repeatability measurement record

[0136]

[0137]

[0138] It can be seen from the above table that when the verticality and coaxiality of the same lens are repeatedly tested, the deviation of each measurement result from the average value of 10 measurements does not exceed 0.0025mm, and the technical requirements for verticality and coaxiality are generally between 0.02 and 0.04mm. Therefore, it can be considered that the measurement results of this method have high repeatability. The method is used to detect the verticality and coaxiality of the lens, and the results are more accurate.

[0139] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for measuring the verticality and coaxiality of a lens based on a dual-optical path center deviation measuring instrument, characterized in that: The following steps are involved: 1) The lens (3) to be tested is clamped and set on the adjustment platform (41) of the dual-light path center deviation measuring instrument to expose the cylindrical surface of the lens (3) to be tested, and the height of the cylindrical surface exposed from the top surface of the clamping device must be greater than 1 mm; 2) After adjusting the adjustment platform (41) until the upper and lower surfaces of the lens (3) to be tested form clear reflection images, a flat crystal (4) is placed on the edge surface (31) of the lens (3) to be tested, and the lens of the upper optical path (42) is removed, and the adjustment platform (41) is adjusted until the angle error of the upper surface of the display interface is within 2"; 3) Remove the flat crystal (4) and reinstall the lens into the upper optical path (42), input the curvature radius of the upper and lower surfaces of the lens (3) to be tested and the lens parameters, obtain the angular error β of the upper and lower surfaces of the lens (3) to be tested by a dual optical path center deviation measuring instrument, adjust the adjustment platform (41) until the angular error β meets the requirement, if not, return to step 2); 4) Using a micrometer to measure the runout value of the dragging surface (31) of the lens (3) to be tested as the verticality of the lens, and using a micrometer to measure the 1 / 2 runout value of the cylindrical surface of the lens (3) to be tested as the coaxiality of the lens.

2. The method according to claim 1, characterized in that The requirement for the angle error β is: 1) When the radius of curvature of the lens (3) to be tested is ≤15mm, the angle error β is required to be ≤15"; 2) When the radius of curvature of the lens (3) to be tested is 15-40 mm or 40 mm, the angle error β is required to be ≤10"; 3) When the radius of curvature of the lens (3) to be tested is 40-100 mm or 100 mm, the angle error β is required to be ≤5"; 4) When the radius of curvature of the lens (3) to be tested is 100-500 mm or 500 mm, the angle error β is required to be ≤ 2"; 5) When the radius of curvature of the lens (3) to be tested is greater than 500, the angle error β is required to be ≤ 1".

3. The method according to claim 1, characterized in that The edge thickness of the lens (3) to be tested must be greater than or equal to 1.5 mm; Preferably, the lens (3) to be tested is an axisymmetric rotation lens.

4. The method according to claim 1, characterized in that: When the aperture of the flat crystal (4) is ≤100 mm, the aperture N of the flat crystal (4) surface is ≤3, the local aperture △N is ≤1, and the local aperture △N in the area within 50 mm of the center of the flat crystal (4) is ≤0.5; Preferably, when the aperture of the flat crystal (4) is greater than 100 mm, the surface shape of the flat crystal (4) requires that the aperture N is less than or equal to 4, the local aperture △N is less than or equal to 1, and the local aperture △N within the area within 50 mm of the center of the flat crystal (4) is less than or equal to 0.5; Preferably, the aperture of the flat crystal (4) is larger than the outer diameter of the lens (3) to be tested; Preferably, the diameter of the flat crystal (4) ranges from 40 to 200 mm; Preferably, the thickness of the flat crystal (4) is 4 to 14 mm, and the value is selected to satisfy the diameter-to-thickness ratio of the flat crystal (4) of 10 to 15:1; Preferably, the material used for the flat crystal (4) is K9 glass or a visible light-transmitting material having physical and chemical properties superior to K9 glass; Preferably, the smoothness of the flat crystal (4) is: Grade V, and the parallelism difference between the two surfaces is ≤5".

5. A clamping device for use in the method according to any one of claims 1 to 4, characterized in that: include: An elastic clamp seat (1), an elastic clamp cap (2); The elastic clamp seat (1) is disassembled and arranged on the adjustment platform (41) of the dual-light path center deviation measuring instrument; a through hole is arranged in the elastic clamp seat (1), and the light output end of the lower light path (43) of the dual-light path center deviation measuring instrument is arranged opposite to one end of the through hole of the elastic clamp seat (1); The lens to be tested (3) is placed on the step (114) of the boss (12) of the elastic fixture seat (1); The elastic clamp cap (2) is disposed on the elastic clamp seat (1) and is detachably connected to the elastic clamp seat (1); the inner support surface (112) at the top of the elastic clamp seat (1) is in clamping contact with the cylindrical surface of the lens to be tested (3); and the inner step (114) at the top of the elastic clamp seat (1) is in contact with the lower convex edge of the lens to be tested (3).

6. The device according to claim 5, characterized in that The elastic clamp seat (1) comprises: a base (113), a pedestal (11), and a boss (12); the base (11) is arranged in the central area of ​​the base (113), and the boss (12) is arranged on the base (11); a through hole passes through the base (113), the pedestal (11), and the boss (12); and the lens (3) to be tested is placed on the boss (12); Preferably, a support surface (112) and a step (114) are provided on the upper inner wall of the through hole in the boss (12); the clearance between the support surface (112) on the inner wall of the through hole of the boss (12) above the base (11) and the outer cylindrical surface of the lens (3) to be tested is 0.05 to 0.15 mm; Preferably, the outer circumferential surface of the lens to be tested (3) is exposed above the top surface of the boss (12) by more than 1 mm; Preferably, the total height of the elastic clamp seat (1) is 40 to 55 mm; the thickness of the base (113) is 10 to 20 mm; Preferably, the inner diameter of the step (114) is larger than the effective aperture of the lens (3) to be tested; Preferably, a supporting surface (112) and a step (114) are provided on the upper portion of the boss (12); the supporting surface (112) fits the outer cylindrical surface of the lens (3) to be tested, and the lower convex surface contacts the step (114).

7. The device according to claim 6, characterized in that A plurality of slots (111) are evenly distributed on the top of the circumference of the boss (12); the slot width of the slot (111) is 1 to 2.5 mm, and the depth of the slot (111) is 20 to 25 mm; Preferably, the number of the slots (111) is 2E; when the diameter of the lens (3) to be tested is ≤30 mm, E=3; when the diameter of the lens (3) to be tested is >30 mm, E=4; and when the diameter of the lens (3) to be tested increases by 20 mm, E increases by 1.

8. The device according to claim 5, characterized in that The bottom surface roughness of the base (113) is Ra1.6, and the surface accuracy is better than 0.002mm.

9. The device according to claim 5, characterized in that The through hole arranged at the center of the base (113) has a hole diameter of Φ15-30 mm.

10. The device according to claim 6, characterized in that A threaded structure is provided at the lower part of the inner wall of the elastic clamp cap (2) and is threadedly connected to the threaded structure provided on the outer wall of the base (11); the conical surface of the upper inner wall of the elastic clamp cap (2) is crimped with the conical surface of the outer wall of the upper boss (12) of the elastic clamp; the top support surface (112) of the boss (12) contacts the cylindrical surface of the lens to be tested (3); Preferably, the height of the elastic clamp cap (2) should match that of the elastic clamp seat (1); Preferably, the thread structure of the inner wall of the elastic clamp cap (2) should match the thread structure of the outer wall of the base (11) of the elastic clamp seat (1); Preferably, the conical surface of the inner wall of the elastic clamp cap (2) should match the conical surface of the outer wall of the upper boss (12) of the elastic clamp seat (1).

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