Method for measuring collimation error of photoelectric rotary table

Abstract

The invention discloses a method for measuring the collimation error of a photoelectric rotary table, and solves the technical problem that the existing collimation error measurement method cannot be applied to the photoelectric rotary table of which a pitch axis cannot continuously rotate from 0 degree to 180 degrees along with a visual axis, and the measurement of the pointing precision of the photoelectric rotary table is seriously influenced. The second collimator is placed right behind the first collimator, so that the optical axis of the tested optical system, the central axis of the first collimator and the central axis of the second collimator are located in the same horizontal plane, the pitch angle of the pitch rotating bracket is adjusted to 0 degree, and the pitch rotating bracket is finely adjusted; the center of the cross wire in the first collimator is enabled to coincide with the center of the CCD target surface of the tested optical system, then the azimuth axis is rotated by 180 degrees, the transverse miss distance of the tested optical system is read, and the collimation error can be measured and calculated. The structure is simple, the measurement reliability is high, the photoelectric turntable does not need to be aligned and inverted, and the structural limitation requirement on the photoelectric turntable is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to a collimation error measurement method, in particular to a photoelectric turntable collimation error measurement method. BACKGROUND

[0002] The existing photoelectric turntable includes an azimuth rotating platform, an elevation rotating support and an optical camera mounting rack. The azimuth axis of the azimuth rotating platform can realize 0-360° rotation (i.e. azimuth angle ±180°), so as to realize the circumferential scanning of the optical camera visual axis, such as the guide north, and the elevation axis of the elevation rotating support can realize the adjustment of the elevation angle in the range of 0°-90°-180°, wherein the optical camera visual axis is in a horizontal position, the elevation angle is 0°, the head is lowered for a negative angle, and the head is raised for a positive angle, so as to realize the spatial pointing of the optical camera visual axis in the lowered head, the horizontal position and the raised head, and the elevation angle is 0° when it is called a normal mirror, and the elevation angle is 180° when it is called an inverted mirror. As shown in the ideal case of Figure 4 , the azimuth axis is perpendicular to the plane where the earth is located, the elevation axis is perpendicular to the azimuth axis, and the optical camera visual axis is perpendicular to the elevation axis, i.e. all are 90°. However, in actual application, due to the machining and assembly errors and external force disturbances such as gravity, the three-axis relationship of the photoelectric turntable cannot be completely perpendicular. When the optical camera visual axis is not completely perpendicular to the elevation axis, the error between the actual measurement value of the optical camera and the theoretical value is called collimation error.

[0003] The existing collimation error measurement method is as follows: 1. Place the photoelectric turntable on a flat ground, and level the azimuth rotating platform of the photoelectric turntable; 2. Place the visual axis in a horizontal state, at this time the elevation angle of the optical camera is 0° (i.e. normal mirror position); 3. Place a collimator in the horizontal position in front of the optical camera; 4. Aim the crosshair center in the collimator with the optical camera, and record the azimuth angle reading as A1; 5. Rotate the elevation angle of the optical camera to 180° (i.e. inverted mirror position); 6. Rotate the azimuth axis by about 180°, so that the visual axis of the optical camera is again aligned with the crosshair center in the collimator, and record the azimuth angle reading A2; 7. Calculate the collimation error . This method requires that the visual axis must be able to shoot a normal mirror and an inverted mirror, i.e. the elevation axis can continuously rotate the visual axis of the optical camera from the 0° position to the 180° position, so as to measure the collimation error.

[0004] However, with the development of photoelectric turntable measurement technology, the requirement for the lightness and maneuverability of photoelectric turntable is higher and higher, especially for the space turntable used in the new space range field, the requirement for lightness and integration is high, which causes the limitation of photoelectric turntable structure, such as angle limiting device or insufficient height of U-shaped frame of photoelectric turntable, so that the photoelectric turntable cannot be righted or inverted, that is, the elevation axis cannot continuously rotate with the visual axis from 0° to 180°, in this case, the traditional collimation error measurement method cannot be used, which seriously affects the pointing accuracy measurement of photoelectric turntable. SUMMARY

[0005] In order to solve the technical problem that the existing collimation error measurement method cannot be applied to the photoelectric turntable whose elevation axis cannot continuously rotate with the visual axis from 0° to 180°, and seriously affects the pointing accuracy measurement of the photoelectric turntable, the present application provides a photoelectric turntable collimation error measurement method.

[0006] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme: A photoelectric turntable collimation error measurement method, the photoelectric turntable comprising an azimuth rotating platform, an elevation rotating support and a tested optical system mounting rack; the special feature is that the method comprises the following steps: Step 1: obtaining the photoelectric turntable, placing the photoelectric turntable on a flat ground, and leveling the azimuth rotating platform so that the azimuth axis of the azimuth rotating platform is perpendicular to the ground; Step 2: mounting the tested optical system on the tested optical system mounting rack, adjusting the elevation angle of the elevation rotating support to 0° so that the visual axis of the tested optical system is in a horizontal state; Step 3: placing a first collimator in front of the tested optical system along the visual axis direction, and placing a second collimator behind the tested optical system along the visual axis direction, so that the visual axis, the central axis of the first collimator and the central axis of the second collimator are on the same axis; Step 4: aiming at the center of the crosshair in the first collimator with the tested optical system, and adjusting the elevation rotating support so that the center of the CCD target surface of the tested optical system coincides with the center of the crosshair in the first collimator; Step 5: rotating the azimuth axis by 180° so that the visual axis aims at the second collimator, and reading the lateral miss distance of the tested optical system Step 6: calculating the collimation error , completing the photoelectric turntable collimation error measurement, and the calculation formula is as follows: Wherein, is the focal length of the tested optical system.

[0007] ​​Further, in step 5, the lateral miss distance of the tested optical system is read by the number of pixels of the CCD target surface or by the scale reading of the graticule of the CCD target surface.

[0008] Further, in step 3, the first collimator and the second collimator are long-focus coaxial collimators or long-focus off-axis collimators.

[0009] Further, the focal length of the first collimator and the second collimator is 4-6 times the focal length of the tested optical system.

[0010] Further, the aperture of the first collimator is , the aperture of the second collimator is , and the aperture of the tested optical system is , then: , wherein, , is a constant, and , .

[0011] Further, the tested optical system is an optical camera.

[0012] Advantages of the present application: 1. The present application is a method for measuring the collimation error of an optoelectronic turntable. The first collimator is placed in front of the tested optical system, and the second collimator is placed behind the tested optical system. The optical axis of the tested optical system, the central axis of the first collimator, and the central axis of the second collimator are located in the same horizontal plane. The pitch angle of the pitch rotation support is adjusted to 0°, and the pitch rotation support is finely adjusted so that the center of the crosshair in the first collimator coincides with the center of the CCD target surface of the tested optical system. Then, the azimuth axis is rotated by 180°, and the lateral miss distance of the tested optical system is read. The collimation error can be measured and calculated. The measurement method is simple, and the measurement reliability is high. The optical turntable does not need to be calibrated, and the structural limitation requirement of the traditional collimation error measurement method is reduced, which is beneficial to the miniaturization development of the optoelectronic turntable.

[0013] 2. The present application is a method for measuring the collimation error of an optoelectronic turntable. The lateral miss distance of the tested optical system is read by the number of pixels of the CCD target surface or by the scale reading of the graticule of the CCD target surface. The naked eye alignment accuracy can reach , and the alignment accuracy is high, thereby improving the reading accuracy of the lateral miss distance.

[0014] ​​3. The photoelectric turntable collimation error measurement method eliminates the azimuth angle reading error through the lateral miss distance calculation collimation error calculation mode, greatly improves the measurement precision of the collimation error, and is simple, fast and accurate in the azimuth angle calculation mode, and is suitable for alignment, aiming and focusing of a two-axis system.

[0015] 4. The photoelectric turntable collimation error measurement method adopts the coaxial or off-axis first parallel light tube and second parallel light tube with a focal length of four times of the measured optical system, and can cover the application wave band of the measured optical system. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a structural schematic diagram of a photoelectric turntable in an embodiment of the photoelectric turntable collimation error measurement method of the present application; Figure 2 is a horizontal axis rotation schematic diagram of a photoelectric turntable in an embodiment of the photoelectric turntable collimation error measurement method of the present application; Figure 3 is a pitch axis rotation schematic diagram of a photoelectric turntable in an embodiment of the photoelectric turntable collimation error measurement method of the present application; Figure 4 is a three-dimensional schematic diagram of the theoretical relationship among the azimuth axis, the pitch axis and the line of sight of the photoelectric turntable; Figure 5 is a collimation error detection three-dimensional structural schematic diagram of a photoelectric turntable in an embodiment of the photoelectric turntable collimation error measurement method of the present application; Figure 6 is a top view of Figure 5 ; Figure 7 is a miss distance and azimuth angle relationship schematic diagram of a tested optical system in an embodiment of the photoelectric turntable collimation error measurement method of the present application.

[0017] The reference signs are as follows: 1. Azimuth rotation platform; 2. Pitch rotation support; 3. Tested optical system mounting rack; 4. Optical camera; 5. First parallel light tube; 6. Second parallel light tube. DETAILED DESCRIPTION

[0018] The technical solutions of the present application will be described clearly and completely in combination with the drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0019] The photoelectric turntable collimation error measurement method provided in the embodiment of the present application is as follows: Figure 1As shown, the photoelectric turntable comprises an azimuth rotating platform 1, an elevation rotating support 2 and a tested optical system mounting rack 3; in this embodiment, an optical camera 4 is used as the tested optical system, like Figures 2-3 As shown, the method comprises the following steps: Step 1, obtaining the photoelectric turntable, placing the photoelectric turntable on a flat ground and leveling the azimuth rotating platform 1 so that the azimuth axis of the azimuth rotating platform 1 is perpendicular to the ground; Step 2, obtaining the optical camera 4 mounted on the tested optical system mounting rack 3, adjusting the elevation angle of the elevation rotating support 2 to 0° so that the optical axis of the optical camera 4 is in a horizontal state; Step 3, placing a first collimator 5 in front of the optical camera 4 along the optical axis and placing a second collimator 6 behind the optical camera 4 along the optical axis, so that the optical camera 4 has a space with the second collimator 6 after rotating 180° along the azimuth axis, and the optical axis of the optical camera 4, the central axis of the first collimator 5 and the central axis of the second collimator 6 are on the same axis, i.e. the first collimator 5 and the second collimator 6 are on the same horizontal plane, and the included angle between the central axis of the first collimator 5 and the central axis of the second collimator 6 in the horizontal plane is 180°. The commonly used method is to use a higher precision detection theodolite to detect or calibrate the positions of the first collimator 5 and the second collimator 6: placing the first collimator 5 and the second collimator 6 on a free degree platform, manually operating the multi-free degree platform, and micro-adjusting the posture and position of the first collimator 5 and the second collimator 6 so that the included angle between the central axis of the first collimator 5 and the central axis of the second collimator 6 in the horizontal plane is 180° and meets certain precision requirements, such as 0.2 seconds.

[0020] Wherein, the first collimator 5 is a long focal length, coaxial or off-axis collimator, the second collimator 6 is a long focal length, coaxial or off-axis collimator, and the focal length of the first collimator 5 and the second collimator 6 is 4-6 times the focal length of the optical camera 4; the aperture of the first collimator 5 is defined as and the aperture of the second collimator 6 is , the clear aperture of the tested optical system is , then , , wherein , are constants, and , ; in this embodiment, the values of and are 1.2 according to the comprehensive consideration of measurement accuracy and manufacturing cost; the included angle between the two collimators around the azimuth axis is 180°.

[0021] Step 4, aim the center of the cross-hair in the first collimator 5 with the optical camera 4, adjust the elevation rotation support 2 to make the center of the CCD target of the optical camera 4 coincide with the center of the cross-hair in the first collimator 5, at this time the azimuth angle reading is 0°. Step 5, rotate the azimuth axis 180° to make the line of sight aim at the second collimator 6, read the lateral deviation of the optical camera 4 through the number of pixels of the CCD target or the scale of the reticle Step 6, calculate the collimation difference , complete the collimation difference measurement of the photoelectric turntable, the calculation formula is as follows: , the focal length of the optical camera 4.

[0022] The derivation process of the collimation difference calculation formula is as follows: As shown in Figures 5-6 , define the theoretical azimuth angle of the first collimator 5 as , the theoretical azimuth angle of the second collimator 6 as , , the theoretical position of the line of sight, , the actual position of the line of sight, , the theoretical position of the line of sight after the azimuth axis is rotated 180°, , the actual position of the line of sight after the azimuth axis is rotated 180°, then according to the azimuth angle measurement principle of the photoelectric turntable, the following can be obtained: ..................(2) ..................(3) , the azimuth angle reading when the optical camera 4 aims at the first collimator 5; , the azimuth angle reading when the optical camera 4 aims at the second collimator 6; , the azimuth deviation corresponding to the lateral deviation of the optical camera 4 when aiming at the first collimator 5; , the azimuth deviation corresponding to the lateral deviation of the optical camera 4 when aiming at the second collimator 6; As shown in , the azimuth deviation Figure 6 , then: ..................(4) ​​​​​.................. (5) wherein, is the lateral miss distance when the optical camera 4 aims at the first collimator 5; is the lateral miss distance when the optical camera 4 aims at the second collimator 6; As Figure 7 the geometric relationship can be known as: .................. (6) .................. (7) The formula (2) is brought into the formula (6) to obtain: .................. (8) The formula (4) is brought into the formula (8) to obtain: .................. (9) The formula (5) is brought into the formula (3) to obtain: .................. (10) The formula (7) is brought into the formula (10) to obtain: .................. (11) The formula (9) and the formula (11) are equal to obtain: ..... (12) After the arrangement, the following is obtained: ....... (13) Since the crosshair center in the first collimator 5 coincides with the CCD target center of the optical camera 4 when the optical camera 4 aims at the crosshair center in the first collimator 5, so The formula (13) is arranged to obtain: ; The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited to this, any change or replacement within the technical range disclosed by the present application should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for measuring the aiming error of an optoelectronic turntable, the optoelectronic turntable comprising an azimuth rotation platform (1), a pitch rotation support (2), and a mounting bracket (3) for the optical system under test; characterized in that, Includes the following steps: Step 1: Obtain the photoelectric turntable, place the photoelectric turntable on a flat ground, and level the azimuth rotation platform (1) so that the azimuth axis of the azimuth rotation platform (1) is perpendicular to the ground. Step 2: Install the optical system to be tested onto the optical system mounting bracket (3), and adjust the pitch angle of the pitch rotation bracket (2) to 0° so that the visual axis of the optical system to be tested is in a horizontal state; Step 3: Place a first collimator (5) in front of the optical system under test along the direction of the visual axis, and place a second collimator (6) behind it along the direction of the visual axis, so that the visual axis, the central axis of the first collimator (5) and the central axis of the second collimator (6) are on the same axis. Step 4: Aim the optical system under test at the center of the crosshairs inside the first collimator (5), and adjust the pitch rotation bracket (2) to make the center of the CCD target surface of the optical system under test coincide with the center of the crosshairs inside the first collimator (5); Step 5: Rotate the azimuth axis 180° so that the line of sight is aligned with the second collimator (6), and read the lateral miss distance of the optical system under test. ; Step 6: Calculate the collimation error The photoelectric turntable aiming error measurement was completed, and the calculation formula is as follows: ； in, The focal length is the optical system being tested.

2. The photoelectric turntable aiming error measurement method according to claim 1, characterized in that: In step 5, the lateral miss distance of the tested optical system is measured. The reading method is to read the number of pixels on the CCD target surface or to read the scale of the CCD target surface.

3. The photoelectric turntable aiming error measurement method according to claim 1, characterized in that: In step 3, the first collimator (5) and the second collimator (6) are long focal length coaxial collimators or long focal length axis collimators.

4. The photoelectric turntable aiming error measurement method according to claim 3, characterized in that: The focal lengths of the first collimator (5) and the second collimator (6) are both the focal lengths of the optical system under test. 4-6 times.

5. The photoelectric turntable aiming error measurement method according to claim 4, characterized in that: In step 3, the aperture of the first collimator (5) is defined as... The aperture of the second collimator (6) is The aperture of the optical system under test is ,but: , ,in, , All are constants, and , .

6. The photoelectric turntable aiming error measurement method according to claim 1, characterized in that: The optical system under test is an optical camera (4).

Images