CN118131469A - Method for controlling the curvature radius of the spliced primary mirror of a large-aperture telescope - Google Patents

Abstract

The invention provides a curvature radius regulating and controlling method of a spliced primary mirror of a large-caliber telescope, which comprises the following steps: the detectors are respectively placed at the front and rear positions of the ideal curvature center of the spliced main mirror; an ideal spherical wave is sent out by a standard point light source and projected onto a spliced main mirror, and a front-focus defocus image and a rear-focus defocus image are acquired by two detectors respectively; performing linear difference calculation on the pre-focusing and post-focusing defocusing images to obtain a focus position; determining defocusing amount of each sub-mirror in the spliced main mirror according to the focus position; calculating the ideal curvature radius of each sub-mirror according to the defocus amount of each sub-mirror to obtain the integral ideal curvature radius of the spliced main mirror; comparing the curvature radius with the actual curvature radius of the spliced main mirror to obtain correction quantity of the curvature radius of each sub-mirror; each sub-mirror is controlled according to the correction of the respective curvature radius. The invention can measure the correction of the curvature radius of each sub-mirror at one time, does not need to move the imaging component, and improves the adjustment efficiency.

Description

Method for controlling the curvature radius of the spliced primary mirror of a large-aperture telescope

Technical Field

The invention relates to the technical field of spliced primary mirrors for large-aperture telescopes, and in particular to a curvature radius control method for spliced primary mirrors for large-aperture telescopes based on curvature sensing.

Background technique

The technology of splicing primary mirrors is the most effective technical approach to building large astronomical telescopes, such as Kek, HET, LAMOST, TMT and other telescopes. Considering the cost, process basis and actual technical conditions. The most critical part of the spliced telescope system is the realization of splicing the primary mirror, splicing multiple small-sized sub-mirrors together to form a large-aperture telescope, so the curvature radius of the spliced primary mirror needs to be controlled.

The existing control method is to measure the defocus of each sub-mirror one by one by moving the camera, obtain the curvature radius of each sub-mirror according to the defocus of each sub-mirror, and obtain the curvature radius of the entire spliced main mirror, and compare it with the actual curvature radius of the spliced main mirror to obtain the correction amount of the curvature radius of the spliced main mirror for control. This control method requires measuring the defocus of each sub-mirror one by one, and the position of the camera needs to be moved in each measurement, resulting in low control efficiency.

Summary of the invention

The purpose of the present invention is to provide a method for controlling the curvature radius of a spliced primary mirror of a large-aperture telescope to improve the control efficiency.

The present invention provides a method for controlling the curvature radius of a spliced primary mirror of a large-aperture telescope, which is applicable to the case where the splicing seam of the spliced primary mirror is continuous, and comprises the following steps:

S1: A standard point light source and an imaging assembly are placed at the ideal curvature center of the spliced primary mirror. The imaging assembly includes a collimating lens group, two symmetrically arranged plane reflectors, a triangular converging lens and two detectors arranged in sequence along the light transmission direction. The two detectors are respectively located in front and behind the ideal curvature center of the spliced primary mirror;

S2: Use a standard point light source to emit an ideal spherical wave and project it onto the spliced primary mirror, and collect light at the ideal curvature center through reflection from the spliced primary mirror; the light is collimated by the collimator lens group and reflected by two plane reflectors, and then incident on the two reflective surfaces of the triangular reflector. After being reflected and combined by the triangular reflector, the light enters the converging lens, and a focal spot is generated by the converging lens. Two detectors collect the pre-focus defocus image and the post-focus defocus image respectively;

S3: performing linear difference calculation on the defocus image before focusing and the defocus image after focusing to obtain the minimum focal spot position, which is the focal position;

S4: Determine the defocus amount of each sub-mirror in the spliced main mirror according to the focal position;

S5: Calculate the ideal curvature radius of each sub-mirror according to the defocus amount of each sub-mirror to obtain the ideal curvature radius of the entire spliced main mirror;

S6: comparing the ideal curvature radius of the entire spliced primary mirror with the actual curvature radius of the spliced primary mirror to obtain a correction amount of the curvature radius of each sub-mirror;

S7: Each sub-mirror is regulated according to the correction amount of its own curvature radius.

Preferably, the calculation formula of the defocus amount Δz of each sub-mirror is as follows:

Wherein, Δz ₁ and Δz ₂ are the front defocus amount and the rear defocus amount of each sub-mirror respectively.

Another method for controlling the curvature radius of a spliced primary mirror of a large-aperture telescope provided by the present invention is applicable to the case where the splicing seam of the spliced primary mirror is discontinuous, and comprises the following steps:

S1: A standard point light source and an imaging assembly are placed at the ideal curvature center of the spliced primary mirror. The imaging assembly includes a collimating lens group, two symmetrically arranged plane reflectors, a triangular converging lens and two detectors arranged in sequence along the light transmission direction. The two detectors are respectively located in front and behind the ideal curvature center of the spliced primary mirror;

S2: Use a standard point light source to emit an ideal spherical wave and project it onto the spliced primary mirror, and collect light at the ideal curvature center through reflection from the spliced primary mirror; the light is collimated by the collimator lens group and reflected by two plane reflectors, and then incident on the two reflective surfaces of the triangular reflector. After being reflected and combined by the triangular reflector, the light enters the converging lens, and a focal spot is generated by the converging lens. Two detectors collect the pre-focus defocus image and the post-focus defocus image respectively;

S3: Move each sub-mirror and ensure that the two boundaries of each joint are parallel by observing the pre-focus defocus image and the post-focus defocus image;

S4: performing linear difference calculation on the defocus image before focusing and the defocus image after focusing to obtain the minimum focal spot position, which is the focal position;

S5: Determine the defocus amount of each sub-mirror according to the focal position;

S6: Calculate the ideal radius of curvature of each sub-mirror parallel to the seam direction and the ideal radius of curvature perpendicular to the seam direction according to the defocus amount of each sub-mirror, and obtain the ideal radius of curvature of the entire spliced main mirror parallel to the seam direction and the ideal radius of curvature perpendicular to the seam direction;

S7: comparing the ideal curvature radius parallel to the stitching direction and the ideal curvature radius perpendicular to the stitching direction of the entire spliced primary mirror with the actual curvature radius parallel to the stitching direction and the actual curvature radius perpendicular to the stitching direction of the spliced primary mirror, and obtaining the correction amount of the curvature radius parallel to the stitching direction and the correction amount of the curvature radius perpendicular to the stitching direction of each sub-mirror;

S8: Each sub-mirror is regulated according to the corresponding correction amount of the curvature radius parallel to the seam direction and the correction amount of the curvature radius perpendicular to the seam direction.

Preferably, the calculation formula of the defocus amount Δz of each sub-mirror is as follows:

Wherein, Δz ₁ and Δz ₂ are the front defocus amount and the rear defocus amount of each sub-mirror respectively.

Compared with the prior art, the present invention can measure the correction amount of the curvature radius of each sub-mirror at one time, and there is no need to move the imaging component, thereby improving the adjustment efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram showing the principle of a method for controlling the curvature radius of a spliced primary mirror of a large-aperture telescope according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a method for calculating an ideal radius of curvature of a primary mirror when a seam is discontinuous according to an embodiment of the present invention.

Figure numerals: spliced main mirror 1, sub-mirror 11, standard point light source 2, imaging component 3, collimating lens group 31, first plane reflector 32, second plane reflector 33, triangular reflector 34, converging lens 35, first detector 36, second detector 37, focal position 38, correction value 4.

Detailed ways

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the same modules are represented by the same reference numerals. In the case of the same reference numerals, their names and functions are also the same. Therefore, the detailed description thereof will not be repeated.

In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

FIG1 shows the principle of the curvature radius control method of the spliced primary mirror of a large-aperture telescope provided according to an embodiment of the present invention. The curvature radius control method of the spliced primary mirror of a large-aperture telescope provided according to an embodiment of the present invention is described in detail below in conjunction with FIG1. The present invention provides two curvature radius control methods of the spliced primary mirror of a large-aperture telescope, corresponding to the continuous and discontinuous splicing of the primary mirror, respectively.

A method for controlling the curvature radius of a spliced primary mirror of a large-aperture telescope provided in an embodiment of the present invention is applicable to a case where the splicing seam of the spliced primary mirror is continuous, and includes the following steps:

S1: Place a standard point light source 2 and an imaging assembly 3 at the ideal curvature center of the spliced primary mirror 1.

The imaging assembly 3 includes a collimating lens group 31, a first plane reflector 32, a second plane reflector 33, a triangular reflector 34, a converging lens 35, a first detector 36 and a second detector 37 which are arranged in sequence along the light transmission direction; wherein the first plane reflector 32 and the second plane reflector 33 are located in the emission direction of the collimating lens group 31 and are symmetrically arranged, the triangular reflector 34 is located between the first plane reflector 32 and the second plane reflector 33, the two reflecting surfaces of the triangular reflector 34 are directly opposite to the reflecting surfaces of the first plane reflector 32 and the second plane reflector 33, the converging lens 35 is located in the reflecting direction of the triangular reflector 34, and the first detector 36 and the second detector 37 are respectively located in front and back positions of the ideal curvature center of the spliced primary mirror 1.

The spliced main mirror 1 is composed of multiple sub-mirrors 11. The ideal curvature radius is obtained by taking the multiple sub-mirrors 11 as a fitting base surface, and then compared with the actual curvature radius of the spliced main mirror 1 to obtain the correction amount of the curvature radius of each sub-mirror 11.

The purpose of placing the standard point light source and the imaging assembly 2 at the ideal curvature center position of the spliced primary mirror 1 is to obtain an ideal curvature radius.

S2: Use a standard point light source to emit an ideal spherical wave and project it onto the multiple sub-mirrors 11 of the spliced main mirror 1, and collect light at the ideal curvature center through reflection from the multiple sub-mirrors 11; wherein the light is collimated by the collimating lens group 31, reflected by the first plane reflector 32 and the second plane reflector 33, and is incident on the two reflecting surfaces of the triangular reflector 34, and after being reflected and combined by the triangular reflector 34, enters the converging lens 35, and a focal spot is generated by the converging lens 35, and the first detector 36 and the second detector 37 respectively collect and obtain the pre-focus defocus image and the post-focus defocus image.

S3: performing linear difference calculation on the pre-focus defocus image and the post-focus defocus image to obtain a minimum focus spot position, which is the focus position 38 .

S4: Determine the defocus amount of each sub-mirror 11 of the spliced main mirror 1 according to the focal position.

The calculation formula of the defocus amount Δz of each sub-mirror 11 is as follows:

Wherein, Δz ₁ and Δz ₂ are the front defocus amount and the rear defocus amount of each sub-mirror 11 respectively.

S5: Calculate the ideal radius of curvature of each sub-mirror 11 according to the defocus amount of each sub-mirror 11 to obtain the ideal radius of curvature of the entire spliced main mirror 1.

S6: Compare the ideal curvature radius of the entire spliced main mirror with the actual curvature radius of the spliced main mirror 1 to obtain the correction amount 4 of the curvature radius of each sub-mirror 11.

S7: Each sub-mirror 11 is regulated according to the correction amount 4 of its own curvature radius.

The present invention can measure the correction amount of the curvature radius of each sub-mirror 11 at one time, and there is no need to move the imaging component 3, which can improve the adjustment efficiency.

The present invention also provides a method for controlling the curvature radius of a spliced primary mirror of a large-aperture telescope, which is applicable to the case where the splicing seam of the spliced primary mirror is discontinuous, and comprises the following steps:

S1: Place a standard point light source 2 and an imaging assembly 3 at the ideal curvature center of the spliced primary mirror 1.

S2: Use a standard point light source 2 to emit an ideal spherical wave and project it onto the spliced primary mirror 1, and collect light at the ideal curvature center through reflection from the spliced primary mirror 1; wherein the light is collimated by the collimating lens group 31, reflected by the first plane reflector 32 and the second plane reflector 33, and is incident on the two reflecting surfaces of the triangular reflector 34, and after being reflected and combined by the triangular reflector 34, enters the converging lens 35, and a focal spot is generated by the converging lens 35, and the first detector 36 and the second detector 37 respectively collect and obtain the pre-focus defocus image and the post-focus defocus image.

S3: Move each sub-mirror 11 and ensure that the two boundaries of each joint are parallel by observing the pre-focus defocus image and the post-focus defocus image.

S4: performing linear difference calculation on the defocus image before focusing and the defocus image after focusing to obtain the minimum focus spot position, which is the focus position.

S5: Determine the defocus amount of each sub-mirror 11 according to the focal position.

S6: Calculate the ideal radius of curvature of each sub-mirror 11 parallel to the seam direction and the ideal radius of curvature perpendicular to the seam direction according to the defocus amount of each sub-mirror 11, and obtain the ideal radius of curvature of the entire spliced main mirror 1 parallel to the seam direction and the ideal radius of curvature perpendicular to the seam direction.

As shown in Figure 2, for the ideal curvature radius of the spliced main mirror 1 as a whole parallel to the splicing direction, the ideal curvature radius of each sub-mirror 11 parallel to the splicing direction is calculated according to the defocus amount of each sub-mirror 11, and the ideal curvature radius of each sub-mirror 11 parallel to the splicing direction is fitted together to calculate the ideal curvature radius of the spliced main mirror 1 as a whole parallel to the splicing direction.

For the ideal radius of curvature of the spliced main mirror 1 as a whole that is perpendicular to the splicing direction, the ideal radii of curvature of two adjacent sub-mirrors 11 that are perpendicular to the splicing direction are calculated respectively according to the defocus amount of each sub-mirror 11, and then the average value is calculated to obtain the ideal radius of curvature of the spliced main mirror 1 as a whole that is perpendicular to the splicing direction.

S7: Compare the ideal curvature radius parallel to the seam direction and the ideal curvature radius perpendicular to the seam direction of the spliced main mirror 1 as a whole with the actual curvature radius parallel to the seam direction and the actual curvature radius perpendicular to the seam direction of the spliced main mirror 1, and obtain the correction amount of the curvature radius parallel to the seam direction and the correction amount of the curvature radius perpendicular to the seam direction of each sub-mirror 11.

S8: Each sub-mirror 11 is regulated according to the corresponding correction amount of the curvature radius parallel to the joint direction and the correction amount of the curvature radius perpendicular to the joint direction.

It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (4)

1. A method for controlling the curvature radius of a spliced primary mirror of a large-aperture telescope, which is applicable to the case where the spliced seam of the spliced primary mirror is continuous, and is characterized in that it comprises the following steps: S1: A standard point light source and an imaging assembly are placed at the ideal curvature center of the spliced primary mirror. The imaging assembly includes a collimating lens group, two symmetrically arranged plane reflectors, a triangular converging lens and two detectors arranged in sequence along the light transmission direction. The two detectors are respectively located in front and behind the ideal curvature center of the spliced primary mirror; S2: Use a standard point light source to emit an ideal spherical wave and project it onto the spliced primary mirror, and collect light at the ideal curvature center through reflection from the spliced primary mirror; the light is collimated by the collimator lens group and reflected by two plane reflectors, and then incident on the two reflective surfaces of the triangular reflector. After being reflected and combined by the triangular reflector, the light enters the converging lens, and a focal spot is generated by the converging lens. Two detectors collect the pre-focus defocus image and the post-focus defocus image respectively; S3: performing linear difference calculation on the defocus image before focusing and the defocus image after focusing to obtain the minimum focal spot position, which is the focal position; S4: Determine the defocus amount of each sub-mirror in the spliced main mirror according to the focal position; S5: Calculate the ideal curvature radius of each sub-mirror according to the defocus amount of each sub-mirror to obtain the ideal curvature radius of the entire spliced main mirror; S6: comparing the ideal curvature radius of the entire spliced primary mirror with the actual curvature radius of the spliced primary mirror to obtain a correction amount of the curvature radius of each sub-mirror; S7: Each sub-mirror is regulated according to the correction amount of its own curvature radius. 2. The method for controlling the curvature radius of a spliced primary mirror of a large-aperture telescope according to claim 1, wherein the calculation formula for the defocus amount Δz of each sub-mirror is as follows: Wherein, Δz ₁ and Δz ₂ are the front defocus amount and the rear defocus amount of each sub-mirror respectively. 3. A method for controlling the curvature radius of a spliced primary mirror of a large-aperture telescope, which is applicable to the case where the splicing seam of the spliced primary mirror is discontinuous, and is characterized by comprising the following steps: S1: A standard point light source and an imaging assembly are placed at the ideal curvature center of the spliced primary mirror. The imaging assembly includes a collimating lens group, two symmetrically arranged plane reflectors, a triangular converging lens and two detectors arranged in sequence along the light transmission direction. The two detectors are respectively located in front and behind the ideal curvature center of the spliced primary mirror; S2: Use a standard point light source to emit an ideal spherical wave and project it onto the spliced primary mirror, and collect light at the ideal curvature center through reflection from the spliced primary mirror; the light is collimated by the collimator lens group and reflected by two plane reflectors, and then incident on the two reflective surfaces of the triangular reflector. After being reflected and combined by the triangular reflector, the light enters the converging lens, and a focal spot is generated by the converging lens. Two detectors collect the pre-focus defocus image and the post-focus defocus image respectively; S3: Move each sub-mirror and ensure that the two boundaries of each joint are parallel by observing the pre-focus defocus image and the post-focus defocus image; S4: performing linear difference calculation on the defocus image before focusing and the defocus image after focusing to obtain the minimum focal spot position, which is the focal position; S5: Determine the defocus amount of each sub-mirror according to the focal position; S6: Calculate the ideal radius of curvature of each sub-mirror parallel to the seam direction and the ideal radius of curvature perpendicular to the seam direction according to the defocus amount of each sub-mirror, and obtain the ideal radius of curvature of the entire spliced main mirror parallel to the seam direction and the ideal radius of curvature perpendicular to the seam direction; S7: comparing the ideal curvature radius parallel to the stitching direction and the ideal curvature radius perpendicular to the stitching direction of the entire spliced primary mirror with the actual curvature radius parallel to the stitching direction and the actual curvature radius perpendicular to the stitching direction of the spliced primary mirror, and obtaining the correction amount of the curvature radius parallel to the stitching direction and the correction amount of the curvature radius perpendicular to the stitching direction of each sub-mirror; S8: Each sub-mirror is regulated according to the corresponding correction amount of the curvature radius parallel to the seam direction and the correction amount of the curvature radius perpendicular to the seam direction. 4. The method for controlling the curvature radius of a spliced primary mirror of a large-aperture telescope according to claim 3, wherein the calculation formula for the defocus amount Δz of each sub-mirror is as follows: Wherein, Δz ₁ and Δz ₂ are the front defocus amount and the rear defocus amount of each sub-mirror respectively.