CN114235152A

CN114235152A - Miniaturized imaging spectrometer light splitting optical path

Info

Publication number: CN114235152A
Application number: CN202111482617.8A
Authority: CN
Inventors: 王健; 韩希珍
Original assignee: Suzhou Oriental Croto Photoelectric Technology Co ltd
Current assignee: Suzhou Oriental Croto Photoelectric Technology Co ltd
Priority date: 2021-12-07
Filing date: 2021-12-07
Publication date: 2022-03-25

Abstract

The invention relates to a miniaturized imaging spectrometer light splitting path, which comprises a slit, a collimating mirror and a plane blazed grating; the slit is arranged on the front focal plane of the collimating mirror, and the length direction of the opening of the slit is vertical to the optical axis and is parallel to the tangent line of a circle taking the optical axis as the axis; the center of the plane blazed grating is positioned on the back focal plane of the collimating mirror, and the angle of the plane blazed grating can be adjusted according to the wavelength range of incident light; the light transmitted by the slit is collimated by the collimating lens, then enters the plane blazed grating, is split by the plane blazed grating and then returns to the collimating lens; the returned light passes through the collimating lens and then is imaged on an area array detector arranged on the front focal plane of the collimating lens. The invention can realize the dispersion light splitting and imaging of the slit in the imaging spectrometer, avoid the use of high-cost convex blazed gratings and concave blazed gratings, reduce the difficulty of installation and adjustment and make the imaging spectrometer more compact in structure; the invention is mainly suitable for hyperspectral imaging of a spectrometer.

Description

Miniaturized imaging spectrometer light splitting optical path

Technical Field

The invention belongs to the technical field of imaging spectrum, and relates to a miniaturized imaging spectrometer light splitting path based on a plane blazed grating.

Background

The imaging spectrometer can simultaneously obtain two-dimensional space information and one-dimensional spectral information of a detected scene by combining an imaging technology and a spectral technology, has the advantage of map integration, and is widely applied to the fields of satellite remote sensing, military, agriculture, forestry, geology and the like.

The light splitting unit is a core component of the imaging spectrometer. The imaging spectrometer is classified according to a light splitting mode, and is divided into a dispersion type spectrometer and an interference type spectrometer, wherein the market distribution of the dispersion type spectrometer taking blazed gratings as light splitting elements is the widest. In the design of the existing imaging spectrometer, the three parts of collimation, light splitting and focusing are generally designed in a combined mode, wherein the most widely applied design forms are an Offner imaging spectrometer and a Dyson imaging spectrometer. However, the two mainstream design forms of the spectral gratings adopt curved surface gratings, the Offner structure adopts convex surface gratings, the Dyson structure adopts concave surface blazed gratings, the curved surface gratings are difficult to process and high in price, and the reflecting surfaces are more and the assembly difficulty is high; the spectrometer structure based on the plane grating structure comprises three parts of collimation, light splitting and focusing, and the structure is difficult to miniaturize.

The invention content is as follows:

the invention aims to solve the technical problem of providing a miniaturized imaging spectrometer light splitting optical path which can solve the problems of processing difficulty and high price of the existing imaging spectrometer based on blazed grating due to the use of curved surface blazed grating and multi-reflector structure.

In order to solve the technical problem, the light splitting optical path of the miniaturized imaging spectrometer comprises a slit, a collimating mirror and a plane blazed grating; the slit is arranged on the front focal plane of the collimating mirror, and the length direction of the opening of the slit is vertical to the optical axis and is parallel to the tangent line of a circle taking the optical axis as the axis; the center of the plane blazed grating is positioned on the back focal plane of the collimating mirror, and the angle of the plane blazed grating can be adjusted according to the wavelength range of incident light; the light transmitted by the slit is collimated by the collimating lens, then enters the plane blazed grating, is split by the plane blazed grating and then returns to the collimating lens; the returned light passes through the collimating lens and then is imaged on an area array detector arranged on the front focal plane of the collimating lens.

Setting the wavelength range of incident light as lambda 1-lambda 2, and setting the included angle between the principal ray and the optical axis of the incident light emitted by the collimating mirror and incident on the plane blazed grating as theta; the grating constant of the plane blazed grating is d, and the effective diffraction order during working is m; the focal length of the collimating mirror is f; the vertical distance h from the center of the slit to the optical axis satisfies formula (1), and the included angle alpha between the normal of the planar blazed grating and the optical axis satisfies formula (2);

2d sinαcosθ＝mλ₁ (2)

the collimating lens can be a single lens or a lens group.

Advantageous effects

The invention adopts a light splitting mode that the center of the plane blazed grating is arranged on the back focal plane of the collimating mirror, incident light is collimated by the transmission type collimating mirror and returned light is imaged on the area array detector, thereby realizing the dispersion light splitting and imaging of the slit in the imaging spectrometer, avoiding the use of high-cost convex blazed grating and concave blazed grating, reducing the installation and adjustment difficulty and enabling the imaging spectrometer to have a more compact structure; the invention is mainly suitable for hyperspectral imaging of a spectrometer.

Drawings

Fig. 1 is a schematic structural view of the present invention.

In the figure: 1. the device comprises a slit, 2 a collimating mirror, 3 a plane blazed grating, 4 an area array detector, 5 a front focal plane of the collimating mirror and 6 a rear focal plane of the collimating mirror.

Detailed Description

The present invention will be described in further detail with reference to the following drawings and examples, it being understood that the specific embodiments described herein are illustrative of the invention only and are not limiting. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

In the description of the present invention, unless otherwise expressly specified or limited, the terms "connected," "connected," and "fixed" are to be construed broadly, e.g., as meaning permanently connected, removably connected, or integral to one another; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other suitable relationship. The specific meanings of the above terms in the present invention can be specifically understood in specific cases by those of ordinary skill in the art.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," or "beneath" a second feature includes the first feature being directly under or obliquely below the second feature, or simply means that the first feature is at a lesser elevation than the second feature.

In the description of the present embodiment, the terms "upper", "lower", "left", "right", and the like are used in the orientation or positional relationship shown in the drawings only for convenience of description and simplicity of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used only for descriptive purposes and are not intended to have a special meaning.

As shown in fig. 1, the light splitting path of the miniaturized imaging spectrometer of the invention comprises a slit 1, a collimating mirror 2 and a plane blazed grating 3; the slit 1 is arranged on a front focal plane 5 of the collimating mirror, the center of the plane blazed grating 3 is positioned on a rear focal plane 6 of the collimating mirror, and the angle of the plane blazed grating can be adjusted according to the wavelength of incident light; the slit 1 has an opening length direction which is horizontal and vertical to the optical axis, and the opening length direction is vertical to the optical axis and parallel to a tangent of a circle with the optical axis as an axis (i.e., perpendicular to the optical axis and extending in the horizontal direction in fig. 1); the area array detector 4 is arranged on the front focal plane 5 of the collimating mirror and is vertical to the optical axis; the light transmitted by the slit 1 is collimated by the collimating mirror 2, then enters the plane blazed grating 3, is split by the plane blazed grating 3 and then returns to the collimating mirror 2; the returned light passes through the collimating lens 2 and then is imaged on the area array detector 4.

The collimating lens 2 can be a single lens or a lens group.

Setting the wavelength range of incident light as lambda 1-lambda 2, setting the included angle between the principal ray and the optical axis of the incident light emitted by the collimating mirror 2 and incident on the plane blazed grating 3 as theta, setting the included angle between the principal ray and the optical axis of the principal ray diffracted by the plane blazed grating 3 and returned to the collimating mirror 2 as theta, setting the included angle of the normal of the plane blazed grating 3 relative to the optical axis as alpha, setting the grating constant as d, setting the effective diffraction order during hyperspectral work as m, and setting the focal length of the collimating mirror 2 as f; the vertical distance h from the center of the slit 1 to the optical axis satisfies formula (1), and the included angle alpha between the normal of the planar blazed grating 3 and the optical axis satisfies formula (2);

2d sinαcosθ＝mλ₁ (2)

the invention realizes the compact design of the lens group through the telecentric auto-collimation parameter configuration.

Claims

1. A miniaturized imaging spectrometer light splitting path is characterized by comprising a slit, a collimating mirror and a plane blazed grating; the slit is arranged on the front focal plane of the collimating mirror, and the length direction of the opening of the slit is vertical to the optical axis and is parallel to the tangent line of a circle taking the optical axis as the axis; the center of the plane blazed grating is positioned on the back focal plane of the collimating mirror, and the angle of the plane blazed grating can be adjusted according to the wavelength range of incident light; the light transmitted by the slit is collimated by the collimating lens, then enters the plane blazed grating, is split by the plane blazed grating and then returns to the collimating lens; the returned light passes through the collimating lens and then is imaged on an area array detector arranged on the front focal plane of the collimating lens.

2. The light splitting path of the miniaturized imaging spectrometer according to claim 1, wherein the wavelength range of the incident light is set to be λ 1- λ 2, and the included angle between the principal ray emitted by the collimating mirror and incident on the plane blazed grating and the optical axis is set to be θ; the grating constant of the plane blazed grating is d, and the effective diffraction order during working is m; the focal length of the collimating mirror is f; the vertical distance h from the center of the slit to the optical axis satisfies formula (1), and the included angle alpha between the normal of the planar blazed grating and the optical axis satisfies formula (2);

2d sinαcosθ＝mλ₁ (2)。

3. the miniaturized imaging spectrometer optical splitting path according to claim 1 or 2, wherein the collimating lens is a single lens or a set of lenses.