阅读说明：本技术 一种Offner型光谱成像光学系统的快速装调方法 (Rapid adjusting method of Offner type spectral imaging optical system ) 是由 陈新华 赵知诚 杨拓拓 朱嘉诚 沈为民 于 2019-11-06 设计创作，主要内容包括：本发明公开了一种Offner型光谱成像光学系统的快速装调方法。Offner型光谱成像光学系统为同心或接近同心的光学系统,即其主镜、凸面光栅、三镜均为球面,且各自的曲率中心重合或基本重合。本发明基于自准直原理,通过观察点光源经球面镜反射后得到的自准像,快速确定球面镜曲率中心的位置。本发明提供的装调方法具有装调速度快,精度高,对于装调环境的要求低,所需的设备成本低的特点,能快速有效地完成Offner型光谱成像光学系统的装调。(The invention discloses a quick adjustment method of an Offner type spectral imaging optical system. The Offner type spectral imaging optical system is a concentric or nearly concentric optical system, namely, the main mirror, the convex grating and the three mirrors are all spherical surfaces, and the respective curvature centers are coincident or basically coincident. The invention is based on the autocollimation principle, and the position of the curvature center of the spherical mirror is quickly determined by observing the autocollimation image obtained by reflecting the point light source by the spherical mirror. The adjusting method provided by the invention has the characteristics of high adjusting speed, high precision, low requirement on adjusting environment and low cost of required equipment, and can quickly and effectively complete the adjustment of the Offner type spectral imaging optical system.)

1. A method for fast-tuning an Offner-type spectral imaging optical system, comprising the steps of:

(1) marking a curvature center of a main mirror, a curvature center of a three-mirror and a curvature center of a convex grating surface in a spectral imaging optical system with an Offner structure by using a three-coordinate measuring instrument in advance respectively;

(2) fixing the main mirror: placing a transparent glass ball at the curvature center of the marked primary mirror, focusing the auto-collimation microscope on the spherical center of the glass ball, and recording the barycentric coordinate D1 of an image point on the image plane of the auto-collimation microscope detector; removing the glass ball, adjusting the primary mirror to enable the light beam emitted by the auto-collimation microscope to be reflected by the primary mirror, enabling the barycentric coordinate of the image point on the image plane of the auto-collimation microscope detector to be consistent with the barycentric coordinate D1 of the image point recorded in the step, and fixing the primary mirror;

(3) fixing the three mirrors: placing a transparent glass ball at the curvature center of the marked three-mirror, focusing the auto-collimation microscope on the spherical center of the glass ball, and recording the barycentric coordinate D2 of an image point on the image plane of the auto-collimation microscope detector; removing the glass ball, adjusting the three mirrors to enable the light beam emitted by the auto-collimation microscope to be reflected by the three mirrors, enabling the barycentric coordinate of the image point on the image surface of the auto-collimation microscope detector to be consistent with the barycentric coordinate D2 of the image point recorded in the step, and fixing the three mirrors;

(4) an auxiliary concave mirror is arranged on the back of the convex grating, and the curvature center of the auxiliary concave mirror is concentric with the curvature center of the surface of the convex grating; placing a transparent glass ball at the curvature center of the surface of the marked convex grating, focusing the auto-collimation microscope on the spherical center of the glass ball, and recording the gravity center coordinate D3 of an image point on the image plane of the auto-collimation microscope detector; removing the glass ball, and adjusting the auxiliary concave mirror and the convex grating to make the gravity center coordinate of the image point on the image plane of the detector of the auto-collimation microscope consistent with the gravity center coordinate D3 of the image point recorded in the step after the light beam emitted by the auto-collimation microscope is reflected by the auxiliary concave mirror;

(5) installing a slit, and placing an area array detector at the image surface of the spectral imaging optical system; illuminating the slit by a mercury lamp, acquiring a spectral line diagram on an area array detector, and testing spectral line bending; rotating the convex grating according to the spectral line bending test result under the condition that the barycentric coordinate of the image point on the image plane of the auto-collimation microscope detector is consistent with the barycentric coordinate in the step (4) after the mirror is reflected by the auxiliary concave mirror behind the convex grating;

(6) when the spectral line bending meets the requirement, the convex grating is fixed, the auxiliary concave mirror is removed, and the system adjustment is completed.

Technical Field

The invention relates to a method for adjusting an Offner type spectral imaging optical system.

Background

The spectral imaging technology can acquire spatial information and spectral information of a scene at the same time, has the advantage of 'map integration', and is widely applied to the fields of remote sensing detection, mineral exploration, environmental protection monitoring, intelligent agriculture, food safety and the like. The grating type spectral imaging system based on the Offner structure has the advantages of large relative aperture, small distortion, good imaging quality, compact structure and the like, and is one of the most common spectral imaging systems at present. The spectral imaging optical system of the Offner structure usually includes components such as a main mirror, a triple mirror, a convex grating and a slit, and the misalignment of these components can cause the imaging quality of the system to be reduced and the distortion to be increased, which directly affects the quantification level of the spectral imaging.

Before the invention is made, the chinese invention patent CN102141439A discloses an assembling method of a convex grating imaging spectrometer, which is based on an interferometer and adopts a spectrogram direct reading method to realize the assembling of a grating and a detector, and the specific steps are as follows: the main mirror and the three mirrors of the convex grating light splitting system are arranged in front of the interferometer, and the positions of the main mirror and the three mirrors are adjusted to enable the interferometer to generate interference fringes; placing the mercury lamp in front of the slit, placing the grating between the main mirror and the third mirror, placing the reading microscope at the image surface of the convex grating light splitting system, and adjusting the grating to enable the reading microscope to read the 0-level and-1-level spectra of the mercury lamp; and (3) placing a detector and a telescopic lens, and adjusting the detector and the telescopic lens to enable the detector to receive an ideal spectral image of a detected target. The method needs to use an interferometer in the process of adjustment, the price is high, and the time spent in the process of adjustment is long.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides the adjusting method of the Offner type spectral imaging optical system, which has the advantages of high adjusting speed, high precision and low cost.

The technical scheme for realizing the aim of the invention is to provide a quick adjustment method of an Offner type spectral imaging optical system, which comprises the following steps:

(1) marking a curvature center of a main mirror, a curvature center of a three-mirror and a curvature center of a convex grating surface in a spectral imaging optical system with an Offner structure by using a three-coordinate measuring instrument in advance respectively;

(2) fixing the main mirror: placing a transparent glass ball at the curvature center of the marked primary mirror, focusing the auto-collimation microscope on the spherical center of the glass ball, and recording the barycentric coordinate D1 of an image point on the image plane of the auto-collimation microscope detector; removing the glass ball, adjusting the primary mirror to enable the light beam emitted by the auto-collimation microscope to be reflected by the primary mirror, enabling the barycentric coordinate of the image point on the image plane of the auto-collimation microscope detector to be consistent with the barycentric coordinate D1 of the image point recorded in the step, and fixing the primary mirror;

(3) fixing the three mirrors: placing a transparent glass ball at the curvature center of the marked three-mirror, focusing the auto-collimation microscope on the spherical center of the glass ball, and recording the barycentric coordinate D2 of an image point on the image plane of the auto-collimation microscope detector; removing the glass ball, adjusting the three mirrors to enable the light beam emitted by the auto-collimation microscope to be reflected by the three mirrors, enabling the barycentric coordinate of the image point on the image surface of the auto-collimation microscope detector to be consistent with the barycentric coordinate D2 of the image point recorded in the step, and fixing the three mirrors;

(4) an auxiliary concave mirror is arranged on the back of the convex grating, and the curvature center of the auxiliary concave mirror is concentric with the curvature center of the surface of the convex grating; placing a transparent glass ball at the curvature center of the surface of the marked convex grating, focusing the auto-collimation microscope on the spherical center of the glass ball, and recording the gravity center coordinate D3 of an image point on the image plane of the auto-collimation microscope detector; removing the glass ball, and adjusting the auxiliary concave mirror and the convex grating to make the gravity center coordinate of the image point on the image plane of the detector of the auto-collimation microscope consistent with the gravity center coordinate D3 of the image point recorded in the step after the light beam emitted by the auto-collimation microscope is reflected by the auxiliary concave mirror;

(5) installing a slit, and placing an area array detector at the image surface of the spectral imaging optical system; illuminating the slit by a mercury lamp, acquiring a spectral line diagram on an area array detector, and testing spectral line bending; rotating the convex grating according to the spectral line bending test result under the condition that the barycentric coordinate of the image point on the image plane of the auto-collimation microscope detector is consistent with the barycentric coordinate in the step (4) after the mirror is reflected by the auxiliary concave mirror behind the convex grating;

(6) when the spectral line bending meets the requirement, the convex grating is fixed, the auxiliary concave mirror is removed, and the system adjustment is completed.

The Offner type spectral imaging optical system is a concentric or nearly concentric optical system, namely, the main mirror, the convex grating and the three mirrors are all spherical surfaces, and the respective curvature centers are coincident or basically coincident. The invention is based on the autocollimation principle, and the position of the curvature center of the spherical mirror is quickly determined by observing the autocollimation image obtained by reflecting the point light source by the spherical mirror.

Compared with the prior art, the invention provides an adjusting method aiming at the optical structure characteristics of an Offner type spectral imaging optical system and based on the auto-collimation principle, and the adjusting method has the beneficial effects that: the method has the advantages of high installation and adjustment speed, high precision, low requirement on installation and adjustment environment, low cost of required equipment and capability of quickly and effectively completing the installation and adjustment of the Offner type spectral imaging optical system.

Drawings

FIG. 1 is a flow chart of a method for adjusting an Offner type spectral imaging optical system according to an embodiment of the present method;

FIG. 2 is a schematic diagram of the adjustment of the primary mirror and the tertiary mirror;

FIG. 3 is a schematic structural diagram of an auto-collimation microscope;

FIG. 4 is a schematic view of the installation of the convex grating and the auxiliary mirror;

FIG. 5 is a schematic diagram of a coarse-tuning of a grating;

FIG. 6 is a schematic diagram of a fine-tuning of a grating;

in the figure, 1, an autocollimation microscope; 2. a compensation mirror; 3. a glass ball; 4. an auto-collimation microscope; 5. a convex grating; 6, an auxiliary mirror; 7. a primary mirror of the spectral imaging system; 8. three mirrors of a spectral imaging system; 9. a slit; 10. mercury lamps; 11. a CCD camera; 12. a semi-transparent semi-reflective mirror; 13. a microscope objective; 14. a light source; 15. an area array detector; 16. a pinhole.

Detailed Description

The technical solution of the present invention will be further described in detail with reference to the accompanying drawings and examples.