Lens mounting flange distance and center offset integrated measurement device and measurement method

Abstract

The present invention discloses an integrated measurement device and method for lens mounting flange distance and center offset, belonging to the field of optical measurement technology, and aims to solve the problems existing in the prior art. In the present invention, monochromatic light emitted by a light source passes through a light-homogenizing plate and an exit pinhole plate, and is collimated into parallel light by a collimating off-axis parabolic mirror. The light is then reflected by a front beam splitter prism to a rear beam splitter prism. The parallel light then passes through the rear beam splitter prism and propagates to a converging lens. The convergence point of the converging lens is directed to a system to be measured. After being reflected by the system to be measured, the light is again collimated by the converging lens. The collimated light propagates in two paths. One path of the collimated light passes through the rear beam splitter prism and the front beam splitter prism to propagate to an energy converging off-axis parabolic mirror. After being converged by the energy converging off-axis parabolic mirror, the light passes through the incident pinhole plate and enters an optical power detector. The other path of the collimated light is reflected by the rear beam splitter prism to an imaging converging off-axis parabolic mirror. The light is then converged by the imaging converging off-axis parabolic mirror to form an image in a surface array CCD camera.

Description

Technical Field

[0001] The invention belongs to the technical field of optical measurement, and in particular relates to a device and method for integrating lens mounting flange distance and center offset measurement. Background Art

[0002] Transmissive optical systems are generally composed of multiple coaxial lenses. When designing the optical and mechanical structure, it is difficult to achieve precise optical and mechanical assembly by using spacers to separate the lenses to ensure the lens spacing. After assembly and adjustment, due to the eccentricity of each lens and the spacing error between adjacent lenses, it is difficult to assemble and adjust the transmissive system to the expected design specifications. Figure 1 At present, centering adjustment is an important adjustment method to ensure the adjustment accuracy of the transmission optical system. Its principle is: design a lens holder for each lens, first match and repair the line connecting the centers of the two spherical surfaces of the lens (that is, the optical axis of the lens) and the axis of the outer cylindrical surface of the lens holder (the center deviation of a single lens assembly) until they coincide, then perform precision turning on the outer cylindrical surface of the lens holder to ensure the matching tolerance of the inner cylindrical surface of the lens barrel, then correct the distance between the end face of the lens holder and the two spherical vertices of the lens (the lens mounting flange distance) to the theoretical value, and each lens and the lens holder form an independent lens assembly; after trimming each lens assembly according to the above process, install it into the lens barrel in turn, and finally fix it with a pressing ring to complete the assembly of the transmission optical system.

[0003] As can be seen from the principle of centering assembly, the accurate measurement of the lens mounting flange distance and the lens eccentricity is the key to the correct docking of different lens assemblies. If the center deviation of the lens is too large, the coaxiality of the lens group will be destroyed. The deviation of the lens mounting flange distance will directly affect the air gap between adjacent lenses. The above errors will cause the optical performance of the entire system to decrease. The center deviation error is generally measured using a center deviation measuring instrument (also known as a centering instrument). The principle of parallel light imaging through the lens is utilized, and a crosshair is used as an indicator image. By rotating the measured lens, the center radius of the circle formed by the crosshair moving track on the imaging plane is observed to judge the center deviation error of the lens. The Chinese patent publication number CN107339955B discloses a high-precision lens center deviation detection instrument and a measuring method thereof. The Chinese patent publication number CN219349282U discloses a device for adjusting an optical lens by a center deviation measuring instrument. Both center deviation detection devices use a crosshair as an indicator image. By rotating the measured lens, the crosshair moving track on the imaging plane is observed and the center deviation error is judged.

[0004] Interference can be used to measure the air gap between lenses. Using a short-coherent laser as a light source, the Michelson interferometer principle allows for the measurement of both the center thickness of the lens and the air gap between lenses. The optical mirror gap measurement device disclosed in Chinese patent publication number CN103322933A uses short-coherent light as a light source, connected via an optical fiber. Based on the Michelson interferometer principle, the lens to be measured is moved, and the distance the lens moves is determined by observing the changes in the coherent image on the photodetector, thereby determining the air gap between the lenses.

[0005] Currently, almost all center deviation measuring instruments use crosshairs as the object point to generate parallel light, which is then measured through the measuring objective lens. Since the center deviation measuring instrument is only equipped with an area array CCD to receive the return image of the crosshairs, it can only use the size of the fitting circle formed by the trajectory of the crosshairs to determine the eccentricity of the lens or lens group, but cannot obtain the air gap between lenses, let alone measure the mounting flange distance of each single lens assembly in the centering and adjustment process.

[0006] Center-to-center spacing measuring instruments that use short-coherence lasers as light sources and measure lens center thickness and air gaps based on the Michelson interferometer principle can generally only measure the spacing between optical components. When the short-coherence laser converges on a non-mirror diffuse reflection surface (such as the end face of a lens holder), its return light is unlikely to interfere with the measurement optical path, making it impossible to measure the mounting flange distance. Furthermore, short-coherence laser light sources are expensive, and the optical path is often constructed or designed with custom optical fibers, resulting in high equipment costs.

[0007] It can be seen that the center deviation measuring instrument is often used to detect the adjustment eccentricity error of the transmission optical system that has been installed, and the center interval measuring instrument is often used to detect the distance difference between optical parts. The two detection devices use different optical detection systems. Therefore, when measuring the center deviation (the deviation between the lens optical axis and the center line of the outer circle of the lens seat) of the same lens assembly and the lens interval after multiple lens assemblies are installed, the lens assembly needs to be measured on different devices. If the measurement result does not meet the requirements, the mechanical part size needs to be corrected again, and then the above process is repeated to complete the installation. Repeated installation and measurement of different devices may lead to measurement errors, and repeated process flows will also increase the installation time. In addition, neither of the above two devices can measure the installation flange distance.

[0008] For the measurement of flange focal distance, the flange focal distance can be measured by using a fixture to hold a large-scale micrometer to measure the height difference between the center vertex of the lens and the end face of the lens holder. However, this method will cause obvious scratches near the vertex of the lens due to the contact between the measuring ball head of the micrometer and the vertex of the lens, which seriously affects the surface quality of the lens. In addition, it is difficult to ensure that the measuring vertex of the micrometer coincides with the vertex of the lens during measurement. When the curvature radius of the measured lens is small, the error will be very significant. Summary of the Invention

[0009] The purpose of the present invention is to provide an integrated lens mounting flange distance and center offset measurement device and measurement method to solve the problems existing in the prior art of being unable to simultaneously measure center offset and flange distance, low measurement accuracy and high measurement process difficulty.

[0010] The system to be tested targeted by the present invention includes a lens to be tested which is mounted on a lens holder to be tested.

[0011] To achieve the above-mentioned object, the lens mounting flange focal length and center offset integrated measurement device of the present invention comprises a light source, a light homogenizer, an exit pinhole plate, a collimating off-axis parabolic mirror, a front beam splitter prism, a rear beam splitter prism, a converging lens, an imaging converging off-axis parabolic mirror, a surface array CCD camera, an energy converging off-axis parabolic mirror, an incident pinhole plate, and an optical power detector;

[0012] The monochromatic light emitted by the light source forms a circular light-emitting hole through the light homogenizer and the exit pinhole. The light emitted by the exit pinhole is collimated into parallel light by the collimating off-axis parabolic mirror, and then reflected by the front beam splitter prism to the rear beam splitter prism. The parallel light then passes through the rear beam splitter prism and propagates to the converging lens.

[0013] The convergence point of the converging lens reaches the system to be measured, and after being reflected by the system to be measured, it passes through the converging lens again for collimation. The collimated light is propagated in two paths. One path of the collimated light passes through the rear beam splitter prism and the front beam splitter prism to propagate to the energy converging off-axis parabolic mirror. After being converged by the energy converging off-axis parabolic mirror, it passes through the incident pinhole plate and enters the optical power detector; the other path of the collimated light is reflected by the rear beam splitter prism to the imaging converging off-axis parabolic mirror, and then converged by the imaging converging off-axis parabolic mirror to form an image in the area array CCD camera.

[0014] The light source is a monochromatic LED light source.

[0015] The exit pinhole plate and the incident pinhole plate are conjugate with respect to the working surface of the front beam splitter prism.

[0016] The collimating off-axis parabolic mirror can be replaced by the first lens group. The monochromatic light emitted by the light source passes through the light homogenizer and the exit pinhole plate and is collimated by the first lens group before entering the front beam splitter prism.

[0017] The imaging converging off-axis parabolic mirror can be replaced by the second lens group. The light reflected by the system to be measured and collimated by the converging lens is reflected to the first lens group by the rear beam splitter prism, and then converged by the first lens group to form an image on the area array CCD camera.

[0018] The energy-converging off-axis parabolic mirror can be replaced by a third lens group. The light reflected by the system to be measured and collimated by the converging lens passes through the rear beam splitter prism and the front beam splitter prism to the third lens group. After being converged by the third lens group, the light enters the optical power detector through the incident pinhole.

[0019] A measurement method based on an integrated lens mounting flange distance and center offset measurement device includes a lens mounting flange distance measurement method and a lens center offset measurement method;

[0020] The lens mounting flange focal distance measurement method comprises the following steps:

[0021] Step 1: Preliminarily adjust the system to be tested so that the light passing through the converging lens converges at the vertex of the lens to be tested, and after being reflected by the lens to be tested, passes through the converging lens again for collimation. The collimated light passes through the rear beam splitter prism and the front beam splitter prism to propagate to the energy converging off-axis parabolic mirror. After being converged by the energy converging off-axis parabolic mirror, it enters the optical power detector through the incident pinhole plate. Move the system to be tested back and forth so that the converging lens focusing point is located at the vertex of the lens to be tested, the front of the vertex of the lens to be tested, and the rear of the vertex of the lens to be tested, respectively. Record the position information of the system to be tested corresponding to the maximum value detected by the optical power detector as the position information of the system to be tested when the converging lens focusing point is located at the vertex of the lens to be tested.

[0022] Step 2: Preliminarily adjust the system to be tested so that the light passing through the converging lens converges at the end face of the lens holder to be tested, is reflected by the end face of the lens holder to be tested, and is collimated again by the converging lens. The collimated light passes through the rear beam splitter prism and the front beam splitter prism to propagate to the energy converging off-axis parabolic mirror. After being converged by the energy converging off-axis parabolic mirror, it enters the optical power detector through the incident pinhole sheet. Move the system to be tested back and forth so that the converging lens's focal point is located at the end face of the lens holder to be tested, in front of the end face of the lens holder to be tested, and behind the end face of the lens holder to be tested, respectively. Record the position information of the system to be tested corresponding to the maximum value detected by the optical power detector as the position information of the system to be tested when the converging lens's focal point is located at the end face of the lens holder to be tested.

[0023] Step 3: Subtract the position information recorded in step 2 from that in step 1 to obtain the lens mounting flange focal length of the system under test;

[0024] The lens center deviation measurement method comprises the following steps: adjusting the position of the system to be measured or replacing the converging lens so that the light rays converged by the converging lens converge at the spherical center of the mirror surface of the lens to be measured, the converging light rays are reflected by the measured surface of the lens to be measured and return along the original path, the return light rays are collimated by the converging lens, and then reflected by the rear beam splitter prism to an imaging converging off-axis parabolic mirror, and then converged by the imaging converging off-axis parabolic mirror to form an image in an area array CCD camera; rotating the lens holder to be measured around the central axis, and if the position of the circular light spot image in the area array CCD camera remains unchanged, then there is no deviation between the optical axis of the lens to be measured and the center line of the outer circle of the lens holder to be measured; and if the circular light spot image in the area array CCD camera moves along a circular trajectory, then there is a deviation between the optical axis of the lens to be measured and the center line of the outer circle of the lens holder to be measured, and the center deviation of the system to be measured is calculated based on the diameter of the circular trajectory.

[0025] The specific process of obtaining the center deviation of the system to be measured based on the diameter of the circular trajectory is as follows:

[0026] The circular trajectory diameter D can be obtained by fitting the circular trajectory using a circle fitting algorithm;

[0027] Then, the center deviation θ is calculated according to the formula D = 2βRtan(2θ);

[0028] Where: D is the diameter of the trajectory circle;

[0029] β is the vertical axis magnification of the optical system;

[0030] R is the curvature radius of the lens to be tested;

[0031] θ is the angle of the center deviation.

[0032] The beneficial effects of the present invention are as follows: the integrated lens mounting flange distance and center deviation measurement device and measurement method of the present invention introduce a circular light spot as an indicator image, and use the same optical measurement system to achieve the measurement of the lens mounting flange distance and center deviation. The measurement optical system is simplified, and the circular light spot is used as the object point. Not only can the trajectory circle fitting be performed to determine the center deviation in the same way as using a crosshair, but the energy returned by the circular light spot can be detected by the energy detector at the rear through a preset aperture. By comparing the position difference between the two sides at maximum energy, the mounting flange distance can be measured. The measuring device can reduce the measurement process of a single lens assembly during centering and adjustment. The measurement process is all non-contact measurement. Monochromatic LEDs or low-cost lasers can be used as light sources, and one optical path can be used to achieve the required measurement data. While ensuring measurement accuracy, it effectively reduces process difficulty and equipment costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the installation process of the lens assembly on the lens barrel in the prior art;

[0034] Figure 2 This is a schematic diagram of the integrated measuring device for lens mounting flange distance and center offset of the present invention;

[0035] Figure 3 This is a schematic diagram of light transmission when the light convergence point of the lens mounting flange distance and center offset integrated measurement device of the present invention is located at the vertex of the lens surface to be measured;

[0036] Figure 4 This is a schematic diagram of light transmission when the light convergence point of the lens mounting flange distance and center offset integrated measurement device of the present invention is located behind the vertex of the lens surface to be measured;

[0037] Figure 5 This is a schematic diagram of light transmission when the light convergence point of the lens mounting flange distance and center offset integrated measurement device of the present invention is located in front of the vertex of the lens surface to be measured;

[0038] Figure 6 This is a schematic diagram of light transmission when the light convergence point of the lens mounting flange distance and center offset integrated measurement device of the present invention is located at the end face of the lens holder to be measured;

[0039] Figure 7 This is a schematic diagram of light transmission when the light convergence point of the lens mounting flange distance and center offset integrated measurement device of the present invention is located behind the end face of the lens holder to be measured;

[0040] Figure 8 This is a schematic diagram of light transmission when the light convergence point of the lens mounting flange distance and center offset integrated measurement device of the present invention is located in front of the end face of the lens holder to be measured;

[0041] Figure 9 This is a schematic diagram of the relationship between the energy intensity detected by the detector of the lens mounting flange distance and center offset integrated measurement device of the present invention and the position of the system to be measured;

[0042] The components include: 1. Light source, 2. Light homogenizer, 3. Output pinhole, 4. Collimating off-axis parabolic mirror, 5. Front beam splitter, 6. Rear beam splitter, 7. Converging lens, 8. Lens holder to be tested, 9. Lens to be tested, 10. Imaging converging off-axis parabolic mirror, 11. Area array CCD camera, 12. Energy converging off-axis parabolic mirror, 13. Entrance pinhole, 14. Optical power detector. DETAILED DESCRIPTION

[0043] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0044] The system to be tested targeted by the present invention includes a lens to be tested 9 mounted on a lens holder to be tested 8 .

[0045] See also Figure 2 The lens mounting flange distance and center offset integrated measurement device of the present invention comprises a light source 1, a light homogenizer 2, an exit pinhole plate 3, a collimating off-axis parabolic mirror 4, a front beam splitter prism 5, a rear beam splitter prism 6, a converging lens 7, an imaging converging off-axis parabolic mirror 10, a surface array CCD camera 11, an energy converging off-axis parabolic mirror 12, an incident pinhole plate 13, and an optical power detector 14;

[0046] Monochromatic light emitted by light source 1 passes through light homogenizer 2 and exit pinhole plate 3 to form a circular light-emitting hole, producing a circular indicator image; the light emitted by exit pinhole plate 3 is collimated into parallel light by collimating off-axis parabolic mirror 4, and then reflected by front beam splitter prism 5 to rear beam splitter prism 6. The parallel light then passes through rear beam splitter prism 6 and propagates to converging lens 7, which functions to converge the light;

[0047] When measuring the lens mounting flange focal length, the focusing point is the end face of the lens holder 88 to be measured or the mirror vertex of the lens 9 to be measured. The light is reflected by the end face of the lens holder 8 to be measured or the mirror vertex of the lens 9 to be measured and then collimated by the converging lens 7. The collimated light passes through the rear beam splitter prism 6 and the front beam splitter prism 5 to propagate to the energy converging off-axis parabolic mirror 12. After being converged by the energy converging off-axis parabolic mirror 12, it enters the optical power detector 14 through the incident pinhole plate 13. By moving the system to be measured back and forth, the energy passing through the incident pinhole plate 13 can be controlled, thereby affecting the detected energy level.

[0048] When the center of the measuring lens is deviated, the light passing through the converging lens 7 will converge on the spherical center of the measured mirror surface of the lens to be measured 9. At this time, the light will be reflected back to the converging lens 7 along the original path by the measured mirror surface, collimated by the converging lens 7, and then propagated to the rear beam splitter prism 6. It is reflected by the rear beam splitter prism 6 to the imaging converging off-axis parabolic mirror 10, and then converged by the imaging converging off-axis parabolic mirror 10 to form an image in the area array CCD camera 11; when there is a deviation between the central optical axis of the lens to be measured 9 and the center line of the outer circle of the lens holder to be measured 8, the system to be measured is rotated, and the circular image in the area array CCD camera 11 will move along a circular trajectory as the system to be measured rotates.

[0049] The light source 1 is a monochromatic LED light source 1 .

[0050] The exit pinhole plate 3 and the incident pinhole plate 13 are conjugate with respect to the working surface of the front beam splitter prism 5 .

[0051] The collimating off-axis parabolic mirror 4 can be replaced by a first lens group. The monochromatic light emitted by the light source 1 passes through the light homogenizer 2 and the exit pinhole plate 3 and is collimated by the first lens group before entering the front beam splitter prism 5.

[0052] The imaging converging off-axis parabolic mirror 10 can be replaced by a second lens group. The light reflected by the system to be measured and collimated by the converging lens 7 is reflected to the first lens group by the rear beam splitter prism 6, and then converged by the first lens group to form an image on the area array CCD camera 11.

[0053] The energy converging off-axis parabolic mirror 12 can be replaced by a third lens group. The light reflected by the system to be measured and collimated by the converging lens 7 passes through the rear beam splitter prism 6 and the front beam splitter prism 5 to the third lens group. After being converged by the third lens group, it passes through the incident pinhole 13 and enters the optical power detector 14.

[0054] A measurement method based on an integrated lens mounting flange distance and center offset measurement device includes a lens mounting flange distance measurement method and a lens center offset measurement method;

[0055] The lens mounting flange focal distance measurement method comprises the following steps:

[0056] Step 1: See Figure 3-5, preliminarily adjust the system to be tested so that the light passing through the converging lens 7 converges near the vertex of the mirror surface of the lens to be tested 9, and is collimated again after being reflected by the lens to be tested 9, and the collimated light passes through the converging lens 7 again to be collimated, and the collimated light passes through the rear beam splitter 6 and the front beam splitter 5 to propagate to the energy converging off-axis parabolic mirror 12, and after being converged by the energy converging off-axis parabolic mirror 12, it enters the optical power detector 14 through the incident pinhole 13, and moves the system to be tested back and forth so that the focusing point of the converging lens 7 is respectively located at the vertex of the mirror surface of the lens to be tested 9, the front part of the vertex of the mirror surface of the lens to be tested 9, and the rear part of the vertex of the mirror surface of the lens to be tested 9; record the position information of the system to be tested corresponding to the maximum value detected by the optical power detector 14; when the light converges at the vertex of the mirror surface of the lens to be tested 9, the light passes through the off-axis parabolic mirror 13 to be collimated, and the optical power detector 14 is detected. The mirror converges at the incident pinhole plate 13, and the energy entering the pinhole plate is the largest at this time; when the parallel light passing through the converging lens 7 converges before and after the vertex of the mirror surface of the lens to be measured 9, the light is no longer reflected along the original path, and the reflected light is no longer emitted in parallel after passing through the converging lens 7, but has a small divergence angle. The divergent light passes through the rear beam splitter 6 and the front beam splitter prism 5 to propagate to the energy converging off-axis parabolic mirror 12, and after convergence, passes through the incident pinhole plate 13; at this time, no matter whether the parallel light passing through the converging lens 7 converges before or after the vertex of the mirror surface of the lens to be measured 9, only a part of the light converged by the energy converging off-axis parabolic mirror 12 will be able to pass through the incident pinhole plate 13 and enter the optical power detector 14, and the energy is relatively smaller than when it converges at the vertex;

[0057] Here, the light rays passing through the converging lens 7 are converged near the vertex of the mirror surface of the lens to be measured 9, which means that the convergence point of the light rays of the converging lens 7 is located at the vertex of the mirror surface of the lens to be measured 9, in front of the vertex of the mirror surface of the lens to be measured 9, or behind the vertex of the mirror surface of the lens to be measured 9. During the movement, the values ​​detected by the optical power detector 14 include values ​​at positions on, in front of, and behind the vertex of the mirror surface of the lens to be measured 9.

[0058] Step 2: See Figure 6-8 , preliminarily adjust the system to be measured so that the light passing through the converging lens 7 converges near the end face of the lens holder 8 to be measured, and is collimated again by the converging lens 7 after being reflected by the end face of the lens holder 8 to be measured, and the collimated light passes through the rear beam splitter 6 and the front beam splitter prism 5 to propagate to the energy converging off-axis parabolic mirror 12, and after being converged by the energy converging off-axis parabolic mirror 12, enters the optical power detector 14 through the incident pinhole plate 13, and moves the system to be measured back and forth so that the focusing point of the converging lens 7 is respectively located at the end face of the lens holder 8 to be measured, in front of the end face of the lens holder 8 to be measured, and behind the end face of the lens holder 8 to be measured; record the position information of the system to be measured corresponding to the maximum value detected by the optical power detector 14, that is, the position information of the system to be measured when the focusing point of the converging lens 7 is located at the end face of the lens holder 8 to be measured;

[0059] Here, the light rays passing through the converging lens 7 are converged near the end face of the lens holder 8 to be measured. This means that the convergence point of the light rays of the converging lens 7 is located on the end face of the lens holder 8 to be measured, in front of the end face of the lens holder 8 to be measured, or in the rear of the end face of the lens holder 8 to be measured. During the movement, the values ​​detected by the optical power detector 14 include values ​​located on, in front of, and in the rear of the end face of the lens holder 8 to be measured.

[0060] Step 3: Subtract the position information of the system to be tested recorded in step 2 and step 1 to obtain the lens mounting flange focal distance of the system to be tested; see Figure 9 , the solid line represents the energy change curve of the lens holder 8 to be tested, and the dotted line represents the energy change curve of the lens 9 to be tested. The position difference L between the peak values ​​of the two curves is the flange focal length;

[0061] The lens center deviation measurement method is as follows: adjusting the position of the system to be measured or replacing the converging lens 7 so that the light converged by the converging lens 7 converges at the spherical center of the mirror surface of the lens to be measured 9, the converging light is reflected by the measured surface of the lens to be measured 9 and returns along the original path, the returning light is collimated by the converging lens 7, and then reflected by the rear beam splitter prism 6 to the imaging converging off-axis parabolic mirror 10, and is converged by the imaging converging off-axis parabolic mirror 10 to form an image in the area array CCD camera 11; rotating the lens holder 8 to be measured around the central axis, if the position of the circular light spot image in the area array CCD camera 11 remains unchanged, then there is no deviation between the optical axis of the lens to be measured 9 and the center line of the outer circle of the lens holder 8 to be measured; if the circular light spot image in the area array CCD camera 11 moves along a circular trajectory, then there is a deviation between the optical axis of the lens to be measured 9 and the center line of the outer circle of the lens holder 8 to be measured, and the center deviation of the system to be measured is obtained based on the diameter of the circular trajectory.

[0062] The specific process of obtaining the center deviation of the system to be measured based on the diameter of the circular trajectory is as follows:

[0063] The center of the circular light spot in the area array CCD camera 11 is extracted using a center positioning algorithm. When the lens 9 to be tested has a center deviation, the lens 9 to be tested is rotated, and the center of the extracted circular light spot moves along a circular trajectory as the lens 9 to be tested rotates. The circular trajectory is fitted using a circle fitting algorithm to obtain the circular trajectory diameter D.

[0064] Then, the center deviation θ is calculated according to the formula D = 2βRtan(2θ);

[0065] Where: D is the diameter of the trajectory circle;

[0066] β is the vertical axis magnification of the optical system;

[0067] R is the curvature radius of the lens to be tested;

[0068] θ is the angle of the center deviation.

Claims

1. Lens mounting flange distance and center offset integrated measuring device, characterized in that: The invention comprises a light source (1), a light homogenizing plate (2), an exit pinhole plate (3), a collimating off-axis parabolic mirror (4), a front beam splitter prism (5), a rear beam splitter prism (6), a converging lens (7), an imaging converging off-axis parabolic mirror (10), a surface array CCD camera (11), an energy converging off-axis parabolic mirror (12), an incident pinhole plate (13), and an optical power detector (14); Monochromatic light emitted by the light source (1) passes through the light homogenizer (2) and the exit pinhole plate (3) to form a light-emitting circular hole. The light emitted from the exit pinhole plate (3) is collimated into parallel light by the collimating off-axis parabolic mirror (4), and then reflected by the front beam splitter prism (5) to the rear beam splitter prism (6). The parallel light then passes through the rear beam splitter prism (6) and propagates to the converging lens (7). The convergence point of the converging lens (7) is directed to the system to be measured, and after being reflected by the system to be measured, the light is collimated again by the converging lens (7). The collimated light is propagated in two paths. One path of the collimated light passes through the rear beam splitter prism (6) and the front beam splitter prism (5) and propagates to the energy converging off-axis parabolic mirror (12). After being converged by the energy converging off-axis parabolic mirror (12), the light enters the optical power detector (14) through the incident pinhole plate (13); the other path of the collimated light is reflected by the rear beam splitter prism (6) to the imaging converging off-axis parabolic mirror (10), and then is converged by the imaging converging off-axis parabolic mirror (10) to form an image in the area array CCD camera (11).

2. The lens mounting flange focal distance and center offset integrated measuring device according to claim 1, characterized in that: The light source (1) is a monochromatic LED light source (1).

3. The lens mounting flange focal distance and center offset integrated measuring device according to claim 1, characterized in that: The exit pinhole plate (3) and the incident pinhole plate (13) are conjugate with respect to the working surface of the front beam splitter prism (5).

4. The integrated lens mounting flange distance and center offset measurement device according to any one of claims 1 to 3, characterized in that: The collimating off-axis parabolic mirror (4) can be replaced by a first lens group. Monochromatic light emitted by the light source (1) passes through a light homogenizer (2) and an exit pinhole plate (3) and is then collimated by the first lens group and enters a front beam splitter prism (5).

5. The integrated lens mounting flange distance and center offset measurement device according to any one of claims 1 to 3, characterized in that: The imaging converging off-axis parabolic mirror (10) can be replaced by a second lens group. The light reflected by the system to be measured and collimated by the converging lens (7) is reflected to the first lens group by the rear beam splitter prism (6). After being converged by the first lens group, an image is formed on the area array CCD camera (11).

6. The integrated lens mounting flange distance and center offset measurement device according to any one of claims 1 to 3, characterized in that: The energy converging off-axis parabolic mirror (12) can be replaced by a third lens group. The light reflected by the system to be measured and collimated by the converging lens (7) passes through the rear beam splitter prism (6) and the front beam splitter prism (5) to the third lens group. After being converged by the third lens group, the light enters the optical power detector (14) through the incident pinhole plate (13).

7. A measurement method based on the lens mounting flange distance and center offset integrated measurement device according to any one of claims 1 to 3, characterized in that: Including lens mounting flange distance measurement method and lens center deviation measurement method; The lens mounting flange focal distance measurement method comprises the following steps: Step 1: preliminarily adjust the system to be tested so that the light passing through the converging lens (7) converges at the vertex of the mirror surface of the lens to be tested (9), and after being reflected by the lens to be tested (9), passes through the converging lens (7) again for collimation, and the collimated light passes through the rear beam splitter prism (6) and the front beam splitter prism (5) to propagate to the energy converging off-axis parabolic mirror (12), and after being converged by the energy converging off-axis parabolic mirror (12), enters the optical power detector (14) through the incident pinhole plate (13), and moves the system to be tested back and forth so that the converging point of the converging lens (7) is respectively located at the vertex of the mirror surface of the lens to be tested (9), the front part of the vertex of the mirror surface of the lens to be tested (9), and the rear part of the vertex of the mirror surface of the lens to be tested (9); record the position information of the system to be tested corresponding to the maximum value detected by the optical power detector (14) as the position information of the system to be tested when the converging point of the converging lens (7) is located at the vertex of the mirror surface of the lens to be tested (9); Step 2: preliminarily adjusting the system to be tested so that the light passing through the converging lens (7) converges at the end face of the lens holder to be tested (8), is reflected by the end face of the lens holder to be tested (8), and is collimated again by the converging lens (7). The collimated light passes through the rear beam splitter prism (6) and the front beam splitter prism (5) and propagates to the energy converging off-axis parabolic mirror (12). After being converged by the energy converging off-axis parabolic mirror (12), the light enters the optical power detector (14) through the incident pinhole plate (13). The system to be tested is moved forward and backward so that the converging point of the converging lens (7) is respectively located at the end face of the lens holder to be tested (8), the front face of the end face of the lens holder to be tested (8), and the rear face of the end face of the lens holder to be tested (8); and the position information of the system to be tested corresponding to the maximum value detected by the optical power detector (14) is recorded as the position information of the system to be tested when the converging point of the converging lens (7) is located at the end face of the lens holder to be tested (8); Step 3: Subtract the position information recorded in step 2 from that in step 1 to obtain the lens mounting flange focal length of the system under test; The lens center deviation measurement method comprises the following steps: adjusting the position of the system to be measured or replacing the converging lens (7) so that the light converged by the converging lens (7) converges at the spherical center of the mirror surface of the lens to be measured (9); the converging light is reflected by the measured surface of the lens to be measured (9) and returns along the original path; the returning light is collimated by the converging lens (7) and then reflected by the back beam splitter prism (6) to the imaging converging off-axis parabolic mirror (10); the imaging converging off-axis parabolic mirror (10) converges to form an image in the area array CCD camera (11); rotating the lens holder (8) to be measured around the central axis; if the position of the circular light spot image in the area array CCD camera (11) remains unchanged, then the optical axis of the lens to be measured (9) and the center line of the outer circle of the lens holder (8) to be measured have no deviation; if the circular light spot image in the area array CCD camera (11) moves along a circular trajectory, then there is a deviation between the optical axis of the lens to be measured (9) and the center line of the outer circle of the lens holder (8) to be measured; and the center deviation of the system to be measured is obtained according to the diameter of the circular trajectory.

8. The measuring method according to claim 7, characterized in that: The specific process of obtaining the center deviation of the system to be measured based on the diameter of the circular trajectory is as follows: The circular trajectory diameter D can be obtained by fitting the circular trajectory using a circle fitting algorithm; Then, the center deviation θ is calculated according to the formula D = 2βRtan(2θ); Where: D is the diameter of the trajectory circle; β is the vertical axis magnification of the optical system; R is the curvature radius of the lens to be tested; θ is the angle of the center deviation.

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