Opto-Mechanical Structure Design Of The Spatial Amplitude Modulation Spectropolarimeter

Spectropolarimetric detection is a technology that obtains information on spectrum,polarization and space simultaneously.Spectropolarimetric detection technology can offer more information beyond the capacity of intensity detection,and it has characteristics of enhancing target contrast ratio.Therefore,spectropolarimetric detection technology has great application in the fields of astronomy and atmosphere.In this paper,the prototype of the spatial amplitude modulation spectropolarimeter is completed.The structural design of the prototype,the adjustment of the prototype and the experiment of the measurement system are studied.The main research work of the paper is as follows:1 The structure design of the spatial modulation spectropolarimeter prototype.This paper studies the opto-mechanical structure of the prototype,designs the supporting structure of each component on the basis of analyzing the shape and the performance specification of each optical component,and establish the three-dimensional model of the prototype by Solidworks,which mainly solves the rotation adjustment of the slit and the grating,the fixation of the polarizer azimuth,the alignment of optical axis of the wedges,the deflection of the optical path,and the focus adjustment and rotation adjustment of the detector.2 The adjustment of the spatial modulation spectropolarimeter prototype.This paper analyzes the content and difficulty of the adjustment of the prototype and establishes the assembly flow.The alignment method for the collimating lens group,the focusing lens group,and the polarizer,the wedges,the slit,the diffraction grating,the detector are proposed and the assembly tests are finished.The main indicators are tested through the self-collimating theodolite measuring deflection angle,magnifying method measuring the focal length and other means to verify the feasibility of the adjustment program.3 The experimental study of the spatial modulation spectropolarimetric detection system.The experimental research of this paper is divided into two parts,which are the achromatic study of polarization modulation module of the spectropolarimetric measurement system and the experimental research of the prototype.In the achromatic study of the polarization modulation module,the different combo wedges combination experiments are conducted to contrast and confirm the achromatic characteristics through deducing the relationship between the phase retardation of the combo wedges and the crystal refractive index and wedge angle and using Matlab software numerical simulation to determine the optimal combination.In the experimental research of theprototype,the image data under different incident polarization states are obtained through the prototype and the least squares method is used to demodulate the data obtained from the image and the analysis of the prototype error is acquired.