CN2446503Y - High-sensitivity interference imaging spectrum device - Google Patents

Abstract

A high-sensitivity interference imaging spectroscopy device, which is composed of a front optical system, a solid type transverse shearing interferometer, an imaging mirror optical system, a detector, and a signal acquisition and processing system. The solid type transverse shearing interferometer is composed of two glued The half-pentagonal prism is composed of a half-pentagonal prism. The half-pentagonal prism has a certain angle range. One end of the half-pentagonal prism is placed on the front optical system, and the other end is placed on the imaging mirror optical system. The detector is placed at the focal plane of the imaging mirror optical system. The processing system is connected. The utility model has the advantages of simple structure, high energy flux, multi-spectral channels, high signal-to-noise ratio and high stability, and integrates the advantages of time modulation and space modulation.

Description

High Sensitivity Interferometric Imaging Spectroscopy Device

The utility model relates to a high-sensitivity interference imaging spectrum device. It is suitable for land resource exploration, environmental monitoring, marine resource census, natural disaster monitoring and assessment, astronomical research, atmospheric detection, and obtaining rich information in the spatial and spectral dimensions of the measured target. It can simultaneously image the same target in continuous spectral segments.

There are currently three main types of imaging spectrometers. One is the dispersion type, the dispersion type is already in the application stage, it is characterized by simple structure, stable performance, but low energy utilization rate; the other is the interference type, the interference type has high energy flux, multi-spectral channels and hyperspectral resolution and other advantages, but at the same time there is a contradiction between stability and energy flux (that is, the instrument with high flux has poor stability, and improving the stability will reduce the energy flux); in one is the chromatography type, The tomographic type has the advantages of spatial and spectral dimensions, multi-channels and variable resolution, but its over-reliance on large area array detectors limits its practicability.

There are mainly two kinds of interferometric imaging spectroscopy techniques that have emerged, one is time modulation (dynamic) based on Michelson interferometer, and the other is spatial modulation (static) based on transverse shear interferometer. Based on them, many kinds of interferometric imaging spectrometers have emerged. The United States, Japan, and many European countries have successfully developed interferometric imaging spectrometers for aerospace remote sensing. However, each of them has certain defects: such as time-modulated high throughput, high signal-to-noise ratio, and high spectral resolution, but the precision requirements of the moving mirror scanning mechanism are very high, and the optical-mechanical stability is poor, so it is not suitable for harsh conditions such as aerospace. Environment; spatial modulation has high stability, good real-time performance, simple structure, and has the advantages of high throughput under certain conditions, but more often it is similar to the energy flux of dispersive imaging spectrometers. Therefore, the sensitivity and spatial resolution of the instrument are limited. Very restrictive.

In view of the above-mentioned defects, the purpose of this utility model is to provide an interference imaging spectrometer with high energy flux, multi-spectral channels, high signal-to-noise ratio, high stability, and simple structure, that is, a combination of time modulation and space modulation The main advantages are high sensitivity and imaging spectroscopic devices in one body.

In order to achieve the above purpose, the utility model adopts the following technical measures: the high-sensitivity interference imaging spectroscopy device is composed of a front optical system, a solid type transverse shear interferometer, an imaging mirror optical system, a detector, and a signal acquisition and processing system. The idea of the high-sensitivity interference imaging spectroscopy device is to place a front optical system at one end of the solid-type transverse shearing interferometer and an imaging mirror optical system at the other end. The radiation emitted by the target must be collimated light and enter the solid-type Transverse shearing interferometer, the function of the solid type transverse shearing interferometer is to convert one incoming light into two parallel coherent light incident to the imaging mirror system, and then place a detector at the focal plane of the imaging mirror system, To obtain the image of the target with stripes, the detector converts the optical signal into an electrical signal, and the detector is connected to the signal acquisition and processing system. After passing through the signal acquisition and processing system, the image information and spectral information of the target can be obtained at the same time.

Figure 1 is a schematic diagram of a high-sensitivity interference imaging spectroscopy device.

Figure 2 is a schematic diagram of a half pentagonal prism.

Below in conjunction with accompanying drawing, the utility model is described in further detail:

According to Fig. 1 and Fig. 2, it can be seen that the front optical system 1 is placed at one end of the solid type transverse shearing interferometer (2), and the front optical system 1 is composed of a front objective lens a, a field diaphragm c and a collimating mirror b. The objective lens a and the collimating mirror b can be refraction, catadioptric or total reflection. The radiation emitted by the target first forms a primary image through the front objective lens. This image plane is called the primary image plane. The field diaphragm c is placed on the primary focal plane, and the front focal plane of the collimator b must be on the primary image plane. The front optical system 1 has three functions: one is collimation, that is, the light emitted from the front optical system must be collimated light; the other is to adjust the received light energy, if it is a weak radiation target, adjust the front optical system After the internal parameters of 1, the energy entering the optical system can be increased several times; the third is to suppress stray light, which is realized by the field diaphragm c placed on the intermediate image plane. The solid type transverse shearing interferometer 2 is composed of two glued half pentagonal prisms d and e, one of which is coated with a semi-transparent and semi-reflective film. The shapes of the two half pentagonal prisms are similar, and each corresponding angle is equal . The structural diagram of the half-pentagonal prism is shown in Figure 2, where there are multiple options for each angle to achieve the function of lateral shearing. The angle range of the half-pentagonal prism is: angle 1 is between 40°～60°, angle 2 is between 100°～120°, angle 3 is between 110°～130°, angle 4 is between 80°～100° It is more convenient to glue when the angle 4 is 90°. The function of the solid-type transverse shearing interferometer 2 is to cut the light entering the solid-type transverse shearing interferometer 2 into two coherent light rays that are completely parallel and have a certain distance (shearing amount). An imaging mirror optical system 3 is placed at the other end of the solid type transverse shearing interferometer 2, and the imaging mirror optical system 3 collects the sheared target radiation onto the detector 4 located on its image plane, where the radiation interferes and the interference fringes The direction is perpendicular to the shearing direction of the shearing interferometer, and the interference optical path difference is proportional to the shearing amount and the effective size of the detector, and inversely proportional to the focal length of the collecting optical system. The larger the optical path difference, the higher the spectral resolution. The effect of imaging mirror optical system 3 is exactly imaging. A detector 4 is placed at the focal plane of the imaging mirror optical system 3. The detector 4 is a receiver of interference signals. spectral information. The detector 4 is connected to the signal acquisition and processing system 5. The signal acquisition and processing system 5 digitizes the interferogram signal obtained from the detector, sends it to the processor for processing, and finally obtains the spectral information and image information of the target. The optical axis of the front optical system 1 must be perpendicular to a plane of the first half pentagonal prism of the transverse shearing interferometer, and the optical axis of the imaging mirror optical system 3 must also be perpendicular to the corresponding plane of the other half pentagonal prism.

The high-sensitivity interferometric imaging spectrometer is an imaging spectrometer with a new principle. Except for the movement mechanism required for calibration switching, there is no mechanical movement, and it has the characteristics of high stability. The spectrometer uses a Sagnac-type cube transverse shearing interferometer, which uses the two split beams to propagate in the opposite direction along basically the same optical path. Therefore, the requirements for the interferometer itself are not high, but it is necessary to ensure the position and angle of the two mirrors in the structural design relation. The structural design should ensure the requirements of the optical system. The electrical system is mainly composed of image acquisition, central controller, image frame storage, image compression, calibration control, and signal processing. The design of the circuit adopts a large-scale field programmable gate array chip (FPGA). performance is greatly improved. The detector is the receiver of the interference signal. When the instrument works in push-broom mode (a typical working method), the linear array detector can obtain the one-dimensional space and one-dimensional spectral information of the target; the area array detector The two-dimensional space and one-dimensional spectral information of the target can be obtained. Signal processing is to send the digitized interferogram signal to a processor (such as a computer) for processing, and finally obtain the hyperspectral image of the target. The main function of the calibration system is to calibrate the spectral response and radiometric response of the entire instrument system, which can be divided into spectral responsivity calibration, radiometric calibration, relative calibration and absolute calibration.

It is a high-sensitivity interference imaging spectroscopy device integrating the advantages of time modulation and space modulation.

Claims (2)

1. A high-sensitivity interference imaging spectroscopy device, which is composed of a solid type transverse shearing interferometer (2), an imaging mirror optical system (3), and a detector (4), is characterized in that the solid type transverse shearing interferometer (2) Consists of two glued half-pentagonal prisms (d) and (e), one of which is coated with a semi-transparent and semi-reflective film. 2. A high-sensitivity imaging spectrum device according to claim 1, characterized in that the angle range of the half-pentagonal prism is 40°-60° for angle 1, 100°-120° for angle 2, and 110° for angle 3. °～130°, angle 4 is between 80°～100°.

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