光谱学与光谱分析, 2014, 34 (2): 569, 网络出版: 2015-01-13
双弹光拍频调制型Fourier-Bessel变换成像光谱技术研究
Research of Dual-Photoelastic-Modulator-Based Beat Frequency Modulation and Fourier-Bessel Transform Imaging Spectrometer
双弹光调制 成像光谱 傅里叶-贝塞尔变换 拍频 Dual-photoelastic-modulator Imaging spectrometer Fourier-Bessel transform Beat frequency
摘要
针对现有弹光调制器(photoelastic-modulator, PEM)的调制频率高(几十kHz以上), 调制干涉信号频率更高, 普通阵列探测器无法有效采集, 提出了一种基于双弹光调制器拍频调制和傅里叶-贝塞尔(Fourier-Bessel)变换的光谱测量方法, 并结合CCD成像技术构成新型双弹光调制成像光谱技术(dual-photoelastic-modulator-based imaging spectrometer, Dual-PEM-IS)。 该方法将双弹光调制器分别工作在数值略有差异的频率上, 以对光进行拍频调制, 并产生载有被测光的低频调制分量(比驱动频率小2~3个数量级, 普通CCD可实现探测), 通过对调制信号中的低频成分进行Fourier-Bessel变换可得到目标光谱, 使得弹光调制兼具了成像和光谱测量能力。 介绍了其原理并推导出光谱反演公式, 并通过仿真和实验验证其可行性, 分析了光程差的微小偏差对反演光谱造成的影响, 为进一步工程化实现提供了必要的理论基础。
Abstract
As the existing photoelastic-modulator(PEM) modulating frequency in the tens of kHz to hundreds of kHz between, leading to frequency of modulated interference signal is higher, so ordinary array detector cannot effectively caprure interference signal. A new beat frequency modulation method based on dual-photoelastic-modulator (Dual-PEM) and Fourier-Bessel transform is proposed as an key component of dual-photoelastic-modulator-based imaging spectrometer (Dual-PEM-IS) combined with charge coupled device (CCD). The dual-PEM are operated as an electro-optic circular retardance modulator, Operating the PEMs at slightly different resonant frequencies ω1 and ω2 respectively, generates a differential signal at a much lower heterodyne frequency that modulates the incident light. This method not only retains the advantages of the existing PEM, but also the frequency of modulated photocurrent decreased by 2~3 orders of magnitude (10~500 Hz) and can be detected by common array detector, and the incident light spectra can be obtained by Fourier-Bessel transform of low frequency component in the modulated signal. The method makes the PEM has the dual capability of imaging and spectral measurement. The basic principle is introduced, the basic equations is derived, and the feasibility is verified through the corresponding numerical simulation and experiment. This method has potential applications in imaging spectrometer technology, and analysis of the effect of deviation of the optical path difference. This work provides the necessary theoretical basis for remote sensing of new Dual-PEM-IS and for engineering implementation of spectra inversion.
王志斌, 张瑞, 王耀利, 黄艳飞, 陈友华, 王立福, 杨强. 双弹光拍频调制型Fourier-Bessel变换成像光谱技术研究[J]. 光谱学与光谱分析, 2014, 34(2): 569. WANG Zhi-bin, ZHANG Rui, WANG Yao-li, HUANG Yan-fei, CHEN You-hua, WANG Li-fu, YANG Qiang. Research of Dual-Photoelastic-Modulator-Based Beat Frequency Modulation and Fourier-Bessel Transform Imaging Spectrometer[J]. Spectroscopy and Spectral Analysis, 2014, 34(2): 569.