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中国物理学会期刊

新型干涉高光谱成像系统的光束剪切特性分析

CSTR: 32037.14.aps.66.190704

Beam shearing characteristic analysis of interferometric hyperspectral imaging system

CSTR: 32037.14.aps.66.190704
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  • 提出了一种基于新型双折射横向剪切分束器的高光谱成像方法,采用的横向剪切分束器主要由Wollaston棱镜和角锥反射体组成.在分析双折射分束器的偏光结构和分光机理的基础上,利用光线追迹方法分析了光束在Wollaston棱镜中的传播特性,通过计算光束在双折射分束器中的传播方向及出射位置,推导出调制光程差的理论表达公式.根据理论推导结果,分别仿真分析了系统在不同扫描模式下光程差与入射光视场角以及角锥顶点偏移量的调制关系.基于理论分析结果搭建了实验装置,对光程差分析结果进行验证,实验结果与理论分析结果匹配较好.所提方法可以提高剪切光束的平行性,保证干涉条纹的高调制度,降低了复原光谱准确度对光学装调精度和元件加工精度的依赖性,具有结构稳定、复杂度低的显著特点.

     

    A birefringent Fourier transform imaging spectrometer with a new lateral shearing interferometer is presented. The interferometer includes a Wollaston prism and a retroreflector. It splits an incident light beam into two shearing parallel parts to obtain interference fringe patterns of an imaging target, which is well established as an aid in reducing problems associated with optical alignment and manufacturing precision. The proposed method provides a direct technology for robust and inexpensive spectrometers to measure spectral signatures. Formulas for the optical path difference (OPD) produced by the proposed birefringent interferometer are derived by the ray-tracing method. Two experiments are carried out to demonstrate the accuracy of the formulas for OPD in the inner scanning mode and window scanning mode, respectively. A laser of wavelength 650 nm is used as a source of the experimental setup. The experimental estimations of the OPD and a reference OPD curve obtained with theoretical analysis are used for comparison. The match between the two curves is highly consistent, for the maximum deviation of the experimental OPD is less than /4. For the further verification of the imaging performance of the proposed method, another experiment is performed. A scene illuminated by an incandescent lamp is used as an imaging target. The temporal rotating of the retroreflector produces a series of time sequential interferograms, where the target is fixed and fringe patterns move. Performing nonuniform fast Fourier transform of the interferogram data produces a spectral data cube (i.e., the spectral images of the target).A series of recovered spectral images whose center wavelengths range from 450 to 650 nm is presented.In this paper, the principle of the instrument is described, and the OPD distribution formula is obtained and analyzed. The performance of the system is demonstrated through a numerical simulation and three experiments. This work will provide an important theoretical basis and the practical instruction for designing a new type of birefringent Fourier transform spectrometer based on Wollaston prism and its engineering applications.

     

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