一种新型静态成像光谱系统的研究

doi:10.3964/j.issn.1000-0593(2018)09-2971-05

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Abstract The static interference system has the advantages of good stability and strong anti-interference ability, as well as disadvantages of low spectral resolution, nonadjustable spectral resolution, and so on. Aiming at such shortcomings of static interferometric imaging spectroscopy systems, a novel static imaging spectroscopy system is designed in this paper. The system consists of a beam shaping module, a novel static interference modulation module and an imaging module. The beam shaping module is used to shrink and shape the incident light into parallel light, so as to ensure a better interference effect. In addition, the novel static interference modulation module is used to coherently process incident light. The birefringence interference structure is modified in the system. On the basis of unchanged size of the original static interference, the spectral resolution of the system is improved, and the static modulation of the spectral resolution is realized. The imaging module is used to acquire two-dimensional visible images of the target area. The core components of the system consist of two sets of Wollaston prisms, as a spectral device, whose optical axes are orthogonal to each other. The electro-optical modulation module is placed between the two prisms for static scanning of the optical path. Besides, the working principle of the new static imaging spectroscopy system is introduced, and the system data model is given. The function expressions of the main parameters such as angle of incidence and angle of refraction are given, and the system data model is constructed. By plotting ray tracing graphs of the system, the functional equations of the lateral shear of the system are obtained, and the parameters that affect the lateral shear are analyzed and discussed respectively. The extent to which the parameter’s changes of structural angle, crystal thickness and modulation degree affect lateral shear is calculated by simulation. And the extent to which the parameter’s changes of structural angle, crystal thickness affect the spectral resolution is calculated quantitatively. Accordingly, a larger optical path difference can be achieved by appropriately increasing the structural angle and the crystal thickness. Therefore, it is feasible to realize the static scanning of lateral shear by means of electro-optic modulation, by which the acquisition of static spectral images can be achieved. In the experiment, 660 nm laser is tested. Two Wollaston prisms with opposite optical axes (Aperture: 20 mm×20 mm, thickness: 10 mm) and electro-optic modulated crystals (Thickness: 10 mm) are used in the novel static interference module. When modulation degree is 0.000 2 and 0.000 6 respectively, there are obvious differences in the interference fringes obtained by the imaging module. That the density of the interference fringe increases with the increase of modulation degree shows that the greater the modulation degree is, the stronger the spectral static scanning ability is, the more easily the spectral resolution is controlled. Thus, the static imaging spectroscopy system is characterized by adjustable spectral resolution under the condition of controlling the electro-optic crystal modulation degree. The feasibility of the system is verified.

Key words：Imaging spectroscopy system; Lateral shear; Electro-optical modulation; Spectral resolution

Received: 2017-10-26 Accepted: 2018-03-02

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https://www.gpxygpfx.com/EN/10.3964/j.issn.1000-0593(2018)09-2971-05 OR https://www.gpxygpfx.com/EN/Y2018/V38/I09/2971