声光调制光谱相机的成像漂移

Imaging drift of acousto-optic modulator spectral camera

研究了基于声光可调滤波机理的光谱相机在成像时由声光晶体的色散而产生的图像漂移现象。利用色散补偿法和图像位移补偿法,理论计算并实验测量了声光可调滤波器(AOTF)在可见光(488～644 nm)波段内由晶体外衍射角所引起的图像漂移,并进行了优化实验。采用色散补偿法,调整入射光为准平行光,入射光波长为488～644 nm时,在晶体出射面添加0.6°的光楔,晶体外衍射角的变化量可由0.066 50°降低到0.004 2°,即图像漂移量由162.1μm降低到10.9μm;采用图像位移补偿法,不添加光楔,入射光波长为488～644 nm时,图像水平漂移量可从468μm降低到0.658μm,漂移量在一个像元内。实验表明:基于提出的两种方法可忽略成像漂移对图像的影响,有效提高了基于AOTF机理的光谱相机的成像分辨率。

The image drift phenomenon caused by the dispersion of an acousto-optic crystal is researched when the spectral camera is imaging based on acousto-optie tunable filtering mechanism. The image drift caused by the crystal outside diffraction angle is calculated theoretically and measured experimentally by the dispersion compensation and the image displacement compensation methods when a Acousto-optic Tunable Filter（AOTF） is in the visible band of 488 -644 nm, and the experiments are also optimized and analyzed. Using the disper- sion compensation method and in the incident light wavelength of 488 -644 nm, when we adjust the incident subject as a parallel light and add a wedge of 0. 6° in the crystal exit surface, the change of the crystal outside diffraction angle can be reduced from 0. 066 50° to 0. 004 2°, and the image drift is reduced from 162. 1 μm to 10. 9 μm. Using the image displacement compensation method without adding the optical wedge, when the incident light wavelength is in 488 - 644 nm, the image level drift can be reduced from 468 μm to 0. 658 μm within a pixel drift. Experimental results show that the effect of the imaging can be neglected, and the two methods can improve the imaging resolution of the AOTF based on mechanism of the spectral camera.