Device and method for detecting optical axis of aspheric reflector

Abstract

The invention discloses an aspheric reflector optical axis detection device and method, and relates to the technical field of optical measurement, the aspheric reflector optical axis detection device comprises a fixed seat, an interferometer, a laser tracker and an information processing device; the fixing seat is used for fixing an aspheric reflector to be detected, and when the aspheric reflector is fixed by the fixing seat, the axis of the aspheric reflector extends in the left-right direction; the interferometer is arranged on the side of the fixed seat and is movably arranged in the up-down direction, the left-right direction and the front-back direction, and a light source part of the interferometer is arranged towards the fixed seat so as to emit measuring waves towards the aspheric reflector; the laser tracker comprises a target ball, and the target ball can move between the interferometer and the fixed seat in the up-down direction, the left-right direction and the front-back direction and can abut against the peripheral side face of the aspheric reflector. According to the technical scheme, the position of the optical axis of the large-aperture aspheric reflector can be quickly and conveniently determined on the premise that the mirror surface is not damaged.

Description

Technical Field

[0001] The present invention relates to the field of optical measurement technology, and in particular to an optical axis detection device and method for an aspherical reflector. Background Art

[0002] With the continuous development of modern optical detection and processing technology, aspheric optical components are widely used in various fields such as deep space exploration, aerospace remote sensing, and lithography machines. Thanks to the excellent aberration correction capability of aspheric mirrors, the imaging quality and system identification capabilities of aerospace cameras have been greatly improved. In addition, one aspheric mirror can replace multiple spherical components to achieve functions, which greatly simplifies the instrument structure, reduces the weight of the instrument, and effectively reduces the equipment cost.

[0003] Unlike spherical mirrors, aspherical mirrors have only one optical axis, and the mirror surface is rotationally symmetric about the optical axis. Therefore, the position of the optical axis needs to be determined during installation and debugging. However, the related technical methods for detecting the optical axis of aspherical mirrors have problems such as scratching the mirror surface, complex instruments, and unsuitability for large-diameter components.

[0004] Therefore, how to quickly and conveniently determine the optical axis position of a large-aperture aspheric reflector without damaging the mirror surface is an urgent problem to be solved. Summary of the invention

[0005] The main purpose of the present invention is to provide an optical axis detection device and method for an aspheric reflector, aiming to quickly and conveniently determine the optical axis position of the aspheric reflector without damaging the mirror surface.

[0006] To achieve the above-mentioned purpose, the present invention provides an optical axis detection device for an aspheric reflector, which is used to detect the optical axis position of the aspheric reflector. The optical axis detection device for the aspheric reflector comprises a fixing seat, an interferometer, a laser tracker and an information processing device. The fixing seat is used to fix the aspheric reflector to be detected. When the fixing seat fixes the aspheric reflector, the axis of the aspheric reflector extends in the left-right direction. The interferometer is arranged on the side of the fixing seat and is movable in the up-down direction, the left-right direction and the front-back direction. The light source of the interferometer is arranged toward the fixing seat to emit a measurement wave toward the aspheric reflector. The laser tracker comprises a target ball, which can move between the interferometer and the fixing seat in the up-down direction, the left-right direction and the front-back direction and can abut against the peripheral side surface of the aspheric reflector. The information processing device is electrically connected to the laser tracker and is used to read the position information about the target ball in the laser tracker and perform information fitting and information calculation.

[0007] In one embodiment, the optical axis detection device of the aspheric reflector also includes an interferometer adjustment frame, which is used to place the interferometer and drive the interferometer to move; the interferometer adjustment frame includes a first base, a first movable member, a second movable member and a support frame; the first base is arranged on the side of the fixed seat; the first movable member is movably arranged on the first base along the front-back direction; the second movable member is movably arranged on the first movable member along the left-right direction; the support frame is movably arranged on the second movable member along the up-down direction, which is used to place the interferometer.

[0008] In one embodiment, the optical axis detection device of the aspheric reflector also includes a target ball adjustment frame, which is arranged between the interferometer and the fixed seat, and is used to place the target ball and drive the target ball to move between the interferometer and the fixed seat; the target ball adjustment frame includes a second base, a first adjustment member, a second adjustment member and a support seat; the second base is arranged between the interferometer and the fixed seat; the first adjustment member is movably arranged on the second base along the front-back direction; the second adjustment member is movably arranged on the first adjustment member along the left-right direction; the support seat is movably arranged on the second adjustment member along the up-down direction, and is used to place the target ball.

[0009] In addition, the present invention also proposes a method for detecting the optical axis of an aspheric reflector, which is applied to the optical axis detection device of the aspheric reflector as described above, and the method includes the following steps: dividing the reflecting surface of the aspheric reflector into a vertex spherical surface and a plurality of concentric ring zones arranged on the vertex spherical surface; obtaining first position information, wherein the first position information includes the center of curvature position information of the plurality of concentric ring zones, or the center of curvature position information of at least one concentric ring zone and the center of curvature position information of the vertex spherical surface; fitting the first position information to obtain the optical axis position information of the aspheric reflector.

[0010] In one embodiment, after fitting the first position information to obtain the optical axis position information of the aspheric reflector, it also includes: obtaining the axis position information of the aspheric reflector, wherein the axis position information is the position of the central axis of the circumferential side cylinder of the aspheric reflector; calculating the distance and angle between the optical axis of the aspheric reflector and the axis of the aspheric reflector based on the optical axis position information and the axis position information.

[0011] In one embodiment, the step of obtaining the first position information includes: controlling the movement of the interferometer and the target sphere so that the focus of the reference spherical wave of the interferometer coincides with the center of curvature of the vertex sphere, and the target sphere coincides with the focus of the reference spherical wave of the interferometer; obtaining the current position information of the laser tracker as the position information of the center of curvature of the vertex sphere; controlling the movement of the interferometer and the target sphere so that the focus position of the reference spherical wave of the interferometer coincides with the center of curvature of a concentric ring, and the target sphere coincides with the focus of the reference spherical wave of the interferometer; obtaining the current position information of the laser tracker as the position information of the center of curvature of the corresponding concentric ring.

[0012] In one embodiment, the interferometer and the target sphere are controlled to move so that the focus of the reference spherical wave of the interferometer coincides with the center of curvature of the vertex spherical surface. The step of coinciding the focus of the reference spherical wave of the interferometer with the focus of the reference spherical wave of the interferometer includes: controlling the target sphere to move to an avoidance position, and controlling the interferometer to move until an interference pattern with preset stripes appears on the screen of the interferometer; controlling the interferometer to move in the up-down direction, the left-right direction, and the front-back direction until the stripe spacing of the interference pattern reaches a first preset size, at which time the focus of the reference spherical wave of the interferometer coincides with the center of curvature of the vertex spherical surface; controlling the target sphere to move to a position close to the focus of the interferometer, and controlling the target sphere to move at the focus of the interferometer until the interference stripes obtained by the target sphere in the interferometer reach a zero stripe state, at which time the target sphere coincides with the focus of the reference spherical wave of the interferometer.

[0013] In one embodiment, the interferometer and the target sphere are controlled to move so that the focal position of the reference spherical wave of the interferometer coincides with the center of curvature of a concentric annular zone, and the step of coinciding the focus of the reference spherical wave of the interferometer with the focus of the reference spherical wave of the interferometer includes: controlling the target sphere to move to an avoidance position, and controlling the interferometer to move in the left-right direction until an interference pattern with distinguishable annular fringes appears on the screen of the interferometer; controlling the interferometer to move in the up-down direction and the forward-backward direction until the fringe spacing of the annular interference fringes reaches a second preset size, at which time the focal position of the reference spherical wave of the interferometer coincides with the center of curvature of a concentric annular zone; controlling the target sphere to move to a position close to the focus of the interferometer, and controlling the target sphere to move at the focus of the interferometer until the interference fringes obtained by the target sphere in the interferometer reach a zero fringe state, at which time the target sphere coincides with the focus of the reference spherical wave of the interferometer.

[0014] In one embodiment, the step of obtaining the axis position information of the aspheric reflector includes: obtaining second position information and establishing a model based on the second position information to obtain a circumferential cylindrical model, wherein the second position information includes position information of at least six points on the circumferential side surface of the aspheric reflector; and determining the axis position of the aspheric reflector based on the circumferential cylindrical model.

[0015] In one embodiment, the steps of obtaining the second position information and establishing a model based on the second position information to obtain the circumferential cylindrical model include: controlling the target ball to move until it is against the side of the aspheric reflector; reading the current position information of the laser tracker as the point position information on the circumferential side surface; if the correlation between the current multiple point position information does not meet the requirements for building the model, repeatedly confirming the point position information on the circumferential side surface until the circumferential cylindrical model can be established.

[0016] The technical solution of the present invention can generate reference spherical waves with different curvature radii by changing the distance between the interferometer and the aspheric reflector, so that the reference spherical wavefronts with different curvature radii of the interferometer match different annular areas on the aspheric reflector, and obtain interference fringes formed in the annular areas. The interferometer is moved according to the interference fringes so that the focus of the reference spherical wave of the interferometer coincides with the curvature center position of a certain annular area on the aspheric reflector, and then the target ball is placed at a position close to the focus of the interferometer, and then the position of the target ball is fine-tuned according to the interference fringes obtained by the target ball in the interferometer so that the interference fringes are adjusted to a zero fringe state, at which time the center of the target ball coincides with the focus of the reference spherical wave emitted by the interferometer, and then according to the information The processing device obtains the position information of the target sphere, that is, obtains the position information of the center of curvature of a certain annular area on the aspheric reflector, thereby reading the center positions of curvature of at least two annular areas on the aspheric reflector, further performing information fitting and information calculation to obtain the optical axis information of the aspheric reflector, and the target sphere is repeatedly pressed against the peripheral side surface of the aspheric reflector to obtain the central axis position of the aspheric reflector, and the optical axis is associated with the central axis to obtain the position information of the optical axis relative to the central axis. In the process of obtaining the position information, the device is easy to install and does not contact the mirror surface of the aspheric reflector, and can quickly and conveniently determine the optical axis position of a large-aperture aspheric reflector without damaging the mirror surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0019] Figure 1 A schematic structural diagram of an embodiment of an optical axis detection device for an aspheric reflector provided by the present invention; Figure 2 for Figure 1 A schematic diagram of the structure of the aspheric reflector when the target sphere is in the avoidance position; Figure 3 A schematic flow chart of an embodiment of a method for detecting an optical axis of an aspheric reflector provided by the present invention; Figure 4 for Figure 3 Schematic diagram of the process of step S20; Figure 5 for Figure 4 Flow chart of steps S21 and S22; Figure 6 for Figure 4 Flow chart of steps S23 and S24; Figure 7 A schematic flow chart of another embodiment of the optical axis detection method for an aspheric reflector provided by the present invention; Figure 8 for Figure 7 Schematic diagram of the process of step S40; Fig. 9 for Figure 8 Flow chart of step S42; Fig.10 for Figure 7 Schematic diagram of the optical axis position information and axis line position relationship obtained by the optical axis detection method of the aspheric reflector.

[0020] 100. Optical axis detection device for aspheric reflector; 1. interferometer adjustment frame; 11. first base; 12. first moving member; 13. second moving member; 14. support frame; 2. interferometer; 3. laser tracker; 31. target ball; 32. laser transmitter; 4. target ball adjustment frame; 41. second base; 42. first adjustment member; 43. second adjustment member; 44. support seat; 5. information processing equipment; 200. Aspherical reflector.

[0021] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings in conjunction with the embodiments. DETAILED DESCRIPTION

[0022] It should be understood that the specific embodiments described herein are only used to explain the technical solutions of the present invention and are not used to limit the present invention.

[0023] In order to better understand the technical solution of the present invention, a detailed description will be given below in conjunction with the accompanying drawings and specific implementation methods.

[0024] Unlike spherical mirrors, aspherical mirrors have a unique optical axis, and the mirror surface is rotationally symmetrical about the optical axis. Therefore, the optical axis position needs to be determined during installation and debugging, but the related technical methods for detecting the optical axis of aspherical mirrors have problems such as scratching the mirror surface, insufficient precision, and complex instruments.

[0025] Specifically, there are currently three main methods for detecting the optical axis of aspheric mirrors: three-coordinate measurement, centering instrument detection, and interference detection.

[0026] The three-coordinate measurement method is to scan the mirror surface through point contact, fit the obtained mirror space point coordinates to the aspheric surface, and then obtain the optical axis of the aspheric surface. By comparing the fitted optical axis with the reference surface, the inclination and offset of the optical axis can be obtained. Three-coordinate measurement is a contact measurement, which is usually used in the early stage of optical component processing. After the mirror surface is refined or coated, contact measurement may scratch the mirror surface; and the accuracy of three-coordinate measurement will be affected by the measurement range. For the measurement of large-diameter components, the detection accuracy of three-coordinate will decrease, thus affecting the fitting accuracy of the optical axis.

[0027] The optical axis detection of the centering instrument is based on the imaging principle of spherical reflectors. The image passing through the center of the non-spherical sphere will return along the original path, and after passing through the front mirror collimating the objective lens to reach the image surface, when the mirror rotates with the main axis of the centering instrument, the diameter of the motion trajectory of the image point after the light beam is reflected by the surface of the lens being tested can be measured by the centering instrument, so as to calculate the deviation of the approximate center of the sphere; then the displacement of the outer circle and the mirror edge of the optical element being tested on different rings is detected by using a micrometer or displacement sensor, and the turntable is rotated to observe whether the change in the displacement measurement value on the outer circle and the mirror is within the allowable tolerance range, and the optical axis deviation is judged in combination with the measurement result of the approximate center of the sphere of the centering instrument. The centering instrument cannot detect large-diameter components, and cannot measure reflectors with holes in the center area. At the same time, when using a micrometer to contact and measure the displacement deviation of the outer circle or mirror of the component, it is easy to scratch the mirror surface.

[0028] Interferometry is a method of measuring the shape of an aspheric surface by using an interferometer and a specially designed compensator, then using a theodolite or laser tracker to lead out the optical axis of the mirror, and then establish a relationship with other directly measurable benchmarks to obtain the benchmark of the aspheric surface being measured. Interferometry requires a specially designed compensator, multiple benchmark transfers, which are prone to errors, and requires the construction of multiple optical paths, making it more cumbersome to operate.

[0029] Based on this, see Figure 1 and Figure 2According to an embodiment of the present invention, there is provided an optical axis detection device 100 for an aspheric reflector, which is used to detect the optical axis position of an aspheric reflector 200. The optical axis detection device for the aspheric reflector 200 comprises a fixed seat (not shown in the figure), an interferometer 2, a laser tracker 3 and an information processing device 5. The fixed seat is used to fix the aspheric reflector 200 to be detected. When the fixed seat fixes the aspheric reflector 200, the axis of the aspheric reflector 200 extends in the left-right direction. The interferometer 2 is arranged on the side of the fixed seat and is movable in the up-down direction, the left-right direction and the front-back direction. The light source of the interferometer 2 is arranged toward the fixed seat to emit a measurement wave toward the aspheric reflector 200. The laser tracker 3 comprises a target ball 31, which can move between the interferometer 2 and the fixed seat in the up-down direction, the left-right direction and the front-back direction, and can abut against the peripheral side surface of the aspheric reflector 200. The information processing device 5 is electrically connected to the laser tracker 3, which is used to read the position information about the target ball 31 in the laser tracker 3 and perform information fitting and information calculation.

[0030] The technical solution of the present invention can generate reference spherical waves with different curvature radii by changing the distance between the interferometer 2 and the aspheric reflector 200, so that the reference spherical wavefronts with different curvature radii of the interferometer 2 match different annular regions on the aspheric reflector 200, and obtain interference fringes formed in the annular regions. The interferometer 2 is moved according to the interference fringes so that the focus of the reference spherical wave of the interferometer 2 coincides with the curvature center position of a certain annular region on the aspheric reflector 200, and then the target sphere 31 is placed at a position close to the focus of the interferometer 2, and then the position of the target sphere 31 is fine-tuned according to the interference fringes obtained by the target sphere 31 in the interferometer 2, so that the interference fringes are adjusted to a zero fringe state, at which time the center of the target sphere 31 coincides with the focus of the reference spherical wave emitted by the interferometer 2, and then according to the information processing device Preparation 5 obtains the position information of the target sphere 31, that is, obtains the position information of the center of curvature of a certain annular area on the aspheric reflector 200, so as to read the center positions of curvature of at least two annular areas on the aspheric reflector 200, further perform information fitting and information calculation to obtain the optical axis position information of the aspheric reflector 200, and the target sphere 31 is repeatedly offset against the peripheral side surface of the aspheric reflector 200 to obtain the central axis position of the aspheric reflector 200, and the optical axis is associated with the central axis to obtain the position information of the optical axis relative to the central axis. In the process of obtaining the position information, the device is easy to install and does not contact the mirror surface of the aspheric reflector 200, and can quickly and conveniently determine the optical axis position of the large-aperture aspheric reflector 200 without damaging the mirror surface.

[0031] The interferometer 2 sends a measuring wave toward the aspheric reflector 200 , and when the measuring wave returns, it interferes with the internal reference spherical wave to form an interference pattern.

[0032] Furthermore, the laser tracker 3 includes a laser emitter 32 for emitting laser light, and the laser light is emitted toward the target ball 31 to obtain the position information of the target ball 31. The information processing device 5 is selected as a PC, and the PC is connected to the laser tracker 3 to obtain the position information of the measuring point where the target ball 31 is located, and to construct the relevant geometric body using the measurement software related to the laser tracker 3.

[0033] In one embodiment of the present invention, the optical axis detection device 100 of the aspheric reflector also includes an interferometer adjustment frame 1, which is used to place the interferometer 2 and drive the interferometer 2 to move; the interferometer adjustment frame 1 includes a first base 11, a first moving member 12, a second moving member 13 and a support frame 14; the first base 11 is arranged on the side of the fixed seat; the first moving member 12 is arranged on the first base 11 in a forward and backward direction; the second moving member 13 is arranged on the first moving member 12 in a left and right direction; the support frame 14 is arranged on the second moving member 13 in an up and down direction, and is used to place the interferometer 2. In this way, the target ball adjustment frame 4 with three translational degrees of freedom in the technical solution of the present invention can adjust the position of the interferometer 2, so that the reference spherical wavefronts of different curvature radii of the interferometer 2 match different annular areas on the aspheric reflector 200, and obtain interference fringes formed in a certain annular area.

[0034] In one embodiment of the present invention, the optical axis detection device 100 of the aspheric reflector further includes a target ball adjustment frame 4, which is disposed between the interferometer 2 and the fixed seat, and is used to place the target ball 31 and drive the target ball 31 to move between the interferometer 2 and the fixed seat; the target ball adjustment frame 4 includes a second base 41, a first adjustment member 42, a second adjustment member 43 and a support seat 44; the second base 41 is disposed between the interferometer 2 and the fixed seat; the first adjustment member 42 is movably disposed on the second base 41 along the front-back direction; the second adjustment member 43 is movably disposed on the first adjustment member 42 along the left-right direction; the support seat 44 is movably disposed on the second adjustment member 43 along the up-down direction, and is used to place the target ball 31. In this way, the target ball adjustment frame 4 with three translational degrees of freedom in the technical solution of the present invention can adjust the position of the target ball 31, so that the target ball 31 can be placed at the focal position and fine-tuned.

[0035] The present invention also provides a method for detecting the optical axis of an aspherical reflector, see Figure 3 The optical axis detection method of the aspheric reflector is applied to the optical axis detection device 100 of the aspheric reflector as described above, and the method comprises steps S10 to S30: S10, dividing the reflection surface of the aspheric reflection mirror 200 into a vertex spherical surface and a plurality of concentric ring zones sleeved on the vertex spherical surface; It should be noted that the vertex spherical surface is the central part of the aspherical reflector 200 to be tested, and the multiple concentric ring zones arranged on the vertex spherical surface are a series of annular areas gradually extending outward from the vertex spherical surface, and different concentric ring zones have different curvatures.

[0036] S20, obtaining first position information, wherein the first position information includes the curvature center position information of a plurality of concentric ring zones, or the curvature center position information of at least one concentric ring zone and the curvature center position information of the vertex spherical surface; Among them, the position information refers to data that can determine the position of the center of curvature in space, which can be optionally coordinate information; the center of curvature position is the center of curvature position of the spherical surface where the concentric rings or the vertex sphere are located, and in the first position information finally obtained, there are at least two different center of curvature position information.

[0037] S30 , fitting the first position information to obtain the optical axis position information of the aspheric reflector 200 .

[0038] The technical solution of the present invention is based on the feature that the center of curvature position of the vertex spherical surface of the aspheric reflector 200 and the center of curvature position of the concentric ring zones are both on the optical axis. The optical axis position information is obtained by fitting at least two different center of curvature position information, namely, first position information. The first position information is obtained without contacting the mirror surface, thereby quickly and conveniently determining the optical axis position of the large-aperture aspheric reflector 200 without damaging the mirror surface.

[0039] In a feasible implementation manner, the first position information includes the position information of the curvature center of a vertex spherical surface and the position information of the curvature center of a concentric ring. Figure 4 , step S20 comprises: S21, controlling the interferometer 2 and the target sphere 31 to move so that the focus of the reference spherical wave of the interferometer 2 coincides with the center of curvature of the vertex sphere, and so that the target sphere 31 coincides with the focus of the reference spherical wave of the interferometer 2; It should be noted that the target sphere coincides with a certain point when the center point of the target sphere is at the same position as the point. At this time, the center of curvature of the spherical surface where the vertex sphere is located, the focal position of the reference spherical wave of the interferometer 2 coincides with the center point of the current position of the target sphere 31, which is located at point a.

[0040] S22, obtaining the current position information of the laser tracker 3 as the curvature center position information of the vertex spherical surface; The current position information of the laser tracker 3 is the current position information of the target ball 31 , that is, the position information of point a.

[0041] S23, controlling the interferometer 2 and the target sphere 31 to move so that the focal position of the reference spherical wave of the interferometer 2 coincides with the center of curvature of a concentric annular zone, and the target sphere 31 coincides with the focal point of the reference spherical wave of the interferometer 2; At this time, the curvature center position of the spherical surface where the concentric ring zone is located, the focal position of the reference spherical wave of the interferometer 2 and the current position of the target sphere 31 coincide with each other and are located at point b.

[0042] S24, obtaining the current position information of the laser tracker 3 as the curvature center position information of the corresponding concentric ring belt; The current position information of the laser tracker 3 is the current position information of the target ball 31 , that is, the position information of point b.

[0043] In steps S21 to S24, the center of curvature of the vertex spherical surface and the center of curvature of a concentric ring can be quickly and accurately acquired through the movement of the interferometer 2 and the target sphere 31 and the feedback of the interference pattern to obtain the first position information.

[0044] In another feasible implementation manner, the first position information includes two different concentric annular zone curvature center position information, and step S20 includes: S21′, controlling the interferometer 2 and the target sphere 31 to move so that the focus of the reference spherical wave of the interferometer 2 coincides with the center of curvature of a concentric annular zone, and so that the target sphere 31 coincides with the focus of the reference spherical wave of the interferometer 2; S22', obtaining the current position information of the laser tracker 3 as the curvature center position information of the vertex spherical surface; S23', controlling the interferometer 2 and the target sphere 31 to move so that the focal position of the reference spherical wave of the interferometer 2 coincides with the center of curvature of another concentric annulus, so that the target sphere 31 coincides with the focal point of the reference spherical wave of the interferometer 2; S24', obtaining the current position information of the laser tracker 3 as the curvature center position information of the corresponding concentric ring belts.

[0045] In steps S21 ′ to S24 ′, the curvature center positions of two different concentric annular zones can be quickly and accurately acquired through the movement of the interferometer 2 and the target sphere 31 and the feedback of the interference pattern, thereby obtaining the first position information.

[0046] In one embodiment of the present invention, see Figure 5 , step S21 comprises: S211, controlling the target sphere 31 to move to the avoidance position, and controlling the interferometer 2 to move according to the vertex curvature radius of the aspheric reflector 200, until an interference pattern with preset fringes appears on the screen of the interferometer 2; It should be noted that the avoidance position is a position where the target sphere 31 does not affect the measurement wave of the interferometer 2. The interference pattern of the preset fringes is an interference pattern with sparse fringes in the central area and dense fringes in the edge area. At this time, the curvature radius of the reference spherical wave currently emitted by the interferometer 2 matches the curvature radius of the vertex spherical surface on the aspherical reflector 200, and the deviation between the reference spherical wave wavefront and the vertex spherical surface is reduced to within the measurement range of the interferometer 2, so clear fringes can be seen in the interferometer 2.

[0047] S212, controlling the interferometer 2 to move in the up-down, left-right, and front-back directions until the fringe spacing of the interference pattern reaches a first preset size, and at this time, the focus of the reference spherical wave of the interferometer 2 coincides with the center of curvature of the vertex spherical surface; It should be noted that when the fringe spacing of the interference pattern reaches the first preset size, the spacing between every two adjacent fringes is the largest, that is, the fringes are in the sparsest state. At this time, the focus of the reference spherical wave currently emitted by the interferometer 2 coincides with the curvature center of the vertex sphere.

[0048] S213, control the target sphere 31 to move to a position close to the focus of the interferometer 2, and control the target sphere 31 to move at the focus of the interferometer 2 until the interference fringes obtained by the target sphere 31 in the interferometer 2 reach a zero fringe state, at which time, the focus of the target sphere 31 coincides with the focus of the reference spherical wave of the interferometer 2.

[0049] It should be noted that the zero fringe state refers to a uniform brightness distribution in the interference pattern without visible light or dark fringes.

[0050] In steps S211 to S213, the interferometer 2 is controlled to move in the left-right direction so that the curvature radius of the reference spherical wave currently emitted by the interferometer 2 matches the curvature radius of the vertex spherical surface on the aspheric reflector 200, so that the deviation between the reference spherical wave wavefront and the vertex spherical surface is reduced to within the measurement range of the interferometer 2, and then the interferometer 2 is controlled to move in the up-down direction, the left-right direction, and the front-back direction so that the focus of the reference spherical wave currently emitted by the interferometer 2 coincides with the curvature center of the vertex spherical surface. Then, the target sphere 31 is placed at a position close to the focus of the interferometer 2, and then the position of the target sphere 31 is fine-tuned according to the interference fringes obtained by the target sphere 31 in the interferometer 2, so that the interference fringes are adjusted to a zero-fringe state. At this time, the center of the target sphere 31 coincides with the focus of the reference spherical wave of the interferometer 2, so that the curvature center position of the vertex spherical surface can be obtained. For the rotationally symmetric aspheric reflector 200, the curvature center position of the vertex spherical surface is on the optical axis, so that the position information of the vertex spherical surface can be obtained.

[0051] In one embodiment of the present invention, see Figure 6 , step S23 comprises: S231, controlling the target ball 31 to move to the avoidance position, and controlling the interferometer 2 to move in the left and right directions until an interference pattern with distinguishable annular fringes appears on the screen of the interferometer 2; S232, controlling the interferometer 2 to move in the up-down direction and the forward-backward direction until the fringe spacing of the annular interference fringes reaches a second preset size, and at this time, the focal position of the reference spherical wave emitted by the interferometer 2 coincides with the center of curvature of one of the concentric annular zones; It should be noted that the second preset size is when the distance between the current interferometer 2 and the aspheric reflector 200 along the first direction is fixed, and during the process of controlling the interferometer 2 to move in the up-down and forward-backward directions, the distance between every two adjacent fringes is the largest and the fringes are in the sparsest state.

[0052] S233, control the target sphere 31 to move to a position close to the focus of the interferometer 2, and control the target sphere 31 to move at the focus of the interferometer 2 until the interference fringes obtained by the target sphere 31 in the interferometer 2 reach a zero-fringe state. At this time, the target sphere 31 coincides with the focus of the reference spherical wave currently emitted by the interferometer 2.

[0053] In steps S231-S233, by controlling the interferometer 2 to move in the left-right direction, the wavefront of the reference spherical wave of different curvature radii of the interferometer 2 is matched with a concentric annulus, and the deviation of the wavefront of the reference spherical wave and the spherical surface where the concentric annulus is located is reduced to within the measurement range of the interferometer 2, and clear fringes can be seen in the interferometer 2, and then the interferometer 2 is controlled to move in the up-down direction and the forward-backward direction, so that the focus of the reference spherical wave of the interferometer 2 coincides with the center of curvature of the spherical surface where the concentric annulus is located, and then the target sphere 31 is placed at a position close to the focus of the interferometer 2, and finally the position of the target sphere 31 is fine-tuned according to the interference fringes obtained in the interferometer 2, so that the interference fringes are adjusted to a zero-fringe state, at which time the center of the target sphere 31 coincides with the focus of the reference spherical wave of the interferometer 2, and for the rotationally symmetric aspheric reflector 200, the center of curvature of the concentric annulus is also on the optical axis, so that the center of curvature of the concentric annulus can be obtained.

[0054] When performing optical processing, the peripheral cylindrical surface is usually milled out from the blank first, and then the mirror surface is processed with the axis of the peripheral cylinder as the optical axis. Therefore, in an ideal case, the optical axis of the aspheric reflector 200 coincides with the axis of its peripheral cylinder. Therefore, when installing and debugging the aspheric reflector 200, the consistency of the system optical axis can be ensured by ensuring the precise fit between the mirror seat or related mechanical parts and the peripheral cylinder of the aspheric reflector 200, that is, the peripheral cylinder is still used as the reference during installation and debugging. However, if the optical axis is offset or tilted during the mirror processing, that is, the optical axis of the aspheric reflector 200 does not coincide with the axis of the peripheral cylinder, and the peripheral cylinder is still used as a reference during installation and debugging, other optical components in the system may be adjusted significantly, causing the focal plane of the system imaging to deviate from the designed position, or even an unadjustable image quality degradation, thereby rendering the entire system unusable. Therefore, the optical axis of the aspheric reflector 200 must be strictly controlled during the processing, and the optical axis of the aspheric reflector 200 should be detected after the processing is completed to ensure the consistency of the optical axis with the axis of the peripheral cylinder.

[0055] Based on the above examples, please refer to Figure 7 The present invention provides a method for detecting the optical axis of an aspherical reflector, comprising steps S10 to S30 of the above embodiment, and after step S30, further comprising steps S40 and S50: S40, obtaining the axis position information of the aspheric reflector 200, wherein the axis position information is the position of the central axis of the circumferential side cylinder of the aspheric reflector 200; S50, calculating the distance and angle between the optical axis of the aspheric reflector 200 and the axis of the aspheric reflector 200 according to the optical axis position information and the axis position information; See also Fig.10 According to the position information of points a and b, the straight line m where the optical axis of the aspheric reflector 200 is located is fitted, and according to the position information of the straight line m and the position information of the axis l of the aspheric reflector 200, calculation is performed to obtain the distance and angle between the straight line m and the straight line l, that is, the distance and angle between the optical axis of the aspheric reflector 200 and the axis are obtained, so as to install and debug the optical system with the aspheric reflector 200 according to the distance and angle.

[0056] See also Figure 8 In one embodiment of the present invention, step S40 includes S41-S42: S41, acquiring second position information and establishing a model according to the second position information to obtain a circumferential cylindrical model, wherein the second position information includes position information of at least six points on the circumferential side surface of the aspheric reflector 200; The number of point position information on the peripheral side surface is determined according to the shape of the aspherical reflector 200 , so as to establish a model of a peripheral cylinder.

[0057] S42. Determine the position of the axis l of the aspheric reflector 200 according to the circumferential cylindrical model to obtain axis position information.

[0058] See also Figure 4 In steps S41-S42, a model of the circumferential cylinder is established by acquiring position information of at least six points on the circumferential side of the aspherical reflector 200, thereby determining the position of the axis l and obtaining the axis position information.

[0059] In one embodiment of the present invention, see Fig. 9 , step S41 comprises: S411, controlling the target ball 31 to move to abut against the side surface of the aspheric reflector 200; S412, reading the current position information of the laser tracker 3 as the point position information on the peripheral side surface of the aspherical reflector 200; S413: If the correlation relationship between the current multiple point position information does not meet the requirements for building the model, repeatedly confirm the point position information on the peripheral side until the peripheral cylindrical model can be established.

[0060] Steps S411 to S412 obtain position information of multiple points on the peripheral side of the aspherical reflector 200 by moving the target sphere 31, thereby establishing a model of the peripheral cylinder.

[0061] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent scope of the present invention.

Claims

1. An optical axis detection device for an aspheric reflector, used to detect the optical axis position of the aspheric reflector, characterized in that: The detection device of the optical axis of the aspherical reflector comprises: A fixing seat, used for fixing the aspheric reflector to be detected, wherein when the fixing seat fixes the aspheric reflector, the axis of the aspheric reflector extends in the left-right direction; An interferometer is arranged at the side of the fixing seat and is movably arranged in the up-down direction, the left-right direction, and the front-back direction. The light source of the interferometer is arranged toward the fixing seat to emit a measurement wave toward the aspheric reflector. A laser tracker, comprising a target ball, wherein the target ball can move between the interferometer and the fixed seat in the up-down direction, the left-right direction, and the front-back direction, and can abut against the peripheral side surface of the aspheric reflector; and The information processing device is electrically connected to the laser tracker and is used to read the position information of the target ball in the laser tracker and perform information fitting and information calculation.

2. The optical axis detection device of the aspherical reflector according to claim 1, characterized in that: The optical axis detection device of the aspheric reflector also includes an interferometer adjustment frame, which is used to place the interferometer and drive the interferometer to move; The interferometer adjustment frame comprises: A first base, arranged on the side of the fixing base; A first moving member is movably disposed on the base in a forward and backward direction; A second moving member is movably disposed on the first moving member in a left-right direction; and The support frame is movably disposed on the second movable member in an up-and-down direction and is used for placing the interferometer.

3. The optical axis detection device of the aspherical reflector according to claim 1, characterized in that: The optical axis detection device of the aspheric reflector further comprises a target ball adjustment frame, which is arranged between the interferometer and the fixing seat and is used to place the target ball and drive the target ball to move; The target ball adjustment frame comprises: A second base, disposed between the interferometer and the fixing base; A first adjusting member is movably disposed on the second base in a front-rear direction; A second adjusting member is movably disposed on the first adjusting member in a left-right direction; and The support seat is movably arranged on the second adjusting member in the up-down direction and is used for placing the target ball.

4. A method for detecting the optical axis of an aspheric reflector, based on the optical axis detection device of the aspheric reflector according to any one of claims 1 to 3, characterized in that: The optical axis detection method of the aspherical reflector comprises the following steps: Dividing the reflection surface of the aspherical reflector into a vertex spherical surface and a plurality of concentric ring zones sleeved on the vertex spherical surface; Acquire first position information, wherein the first position information includes the center of curvature position information of a plurality of the concentric annular zones, or the center of curvature position information of at least one of the concentric annular zones and the center of curvature position information of the vertex spherical surface; The first position information is fitted to obtain the optical axis position information of the aspheric reflector.

5. The optical axis detection method of the aspheric reflector according to claim 4, characterized in that: After the step of fitting the first position information to obtain the optical axis position information of the aspheric reflector, the method further includes: Acquire the axis position information of the aspheric reflector, wherein the axis position information is the position information of the central axis of the circumferential side cylinder of the aspheric reflector; The distance and angle between the optical axis of the aspheric reflector and the axis of the aspheric reflector are calculated according to the optical axis position information and the axis line position information.

6. The optical axis detection method of the aspheric reflector according to claim 4, characterized in that: The step of obtaining the first location information comprises: Controlling the interferometer and the target sphere to move so that the focus of the reference spherical wave of the interferometer coincides with the center of curvature of the vertex spherical surface, and the target sphere coincides with the focus of the reference spherical wave of the interferometer; Acquiring the current position information of the laser tracker as the center of curvature position information of the vertex spherical surface; Controlling the interferometer and the target sphere to move so that the focal position of the reference spherical wave of the interferometer coincides with the center of curvature of one of the concentric annuli, and so that the target sphere coincides with the focal point of the reference spherical wave of the interferometer; The current position information of the laser tracker is obtained as the corresponding center of curvature position information of the concentric rings.

7. The optical axis detection method of the aspheric reflector according to claim 6, characterized in that: The step of controlling the interferometer and the target sphere to move so that the focus of the reference spherical wave of the interferometer coincides with the center of curvature of the vertex spherical surface, and the step of making the target sphere coincide with the focus of the reference spherical wave of the interferometer comprises: Controlling the target ball to move to an avoidance position, and controlling the interferometer to move until an interference pattern with preset stripes appears on the screen of the interferometer; Controlling the interferometer to move in up-down, left-right, and front-back directions until the fringe spacing of the interference pattern reaches a first preset size, at which time the focus of the reference spherical wave of the interferometer coincides with the center of curvature of the vertex spherical surface; The target ball is controlled to move to a position close to the focus of the interferometer, and the target ball is controlled to move at the focus of the interferometer until the interference fringes obtained by the target ball in the interferometer reach a zero fringes state, at which time the target ball coincides with the focus of the reference spherical wave of the interferometer.

8. The optical axis detection method of the aspheric reflector according to claim 6, characterized in that: The step of controlling the interferometer and the target sphere to move so that the focal position of the reference spherical wave of the interferometer coincides with the center of curvature of one of the concentric annuli, and the step of coinciding the focus of the reference spherical wave of the interferometer with the target sphere comprises: Control the target ball to move to the avoidance position, and control the interferometer to move in the left and right directions until an interference pattern with distinguishable annular fringes appears on the screen of the interferometer; Controlling the interferometer to move in the up-down direction and the forward-backward direction until the fringe spacing of the annular interference fringes reaches a second preset size, and at this time, the focal position of the reference spherical wave of the interferometer coincides with the center of curvature of one of the concentric annuli; The target ball is controlled to move to a position close to the focus of the interferometer, and the target ball is controlled to move at the focus of the interferometer until the interference fringes obtained by the target ball in the interferometer reach a zero fringes state, at which time the center of the target ball coincides with the focus of the reference spherical wave of the interferometer.

9. The optical axis detection method of the aspheric reflector according to claim 5, characterized in that: The step of obtaining the axis position information of the aspheric reflector comprises: Acquire second position information and establish a model according to the second position information to obtain a circumferential cylindrical model, wherein the second position information includes position information of at least six points on the circumferential side surface of the aspherical reflector; The axis position of the aspheric reflector is determined according to the circumferential cylindrical model to obtain the axis position information.

10. The optical axis detection method of the aspheric reflector according to claim 9, characterized in that: The step of acquiring the second position information and establishing a model according to the second position information to obtain a circumferential cylindrical model comprises: Controlling the target ball to move to abut against the side surface of the aspheric reflector; Reading the current position information of the laser tracker as point position information on the peripheral surface; If the correlation relationship between the current multiple point position information does not meet the requirements for building the model, repeatedly confirm the point position information on the peripheral side until the peripheral cylindrical model can be established.

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