传统光学成像要求像面在成像透镜组的焦平面上,以此获得最大的光通量,因此焦距对成像质量影响较大。研究了焦距对计算关联成像成像质量的影响,搭建计算关联成像系统,利用桶探测器信号的强度涨落分析不同焦距下的关联成像结果,分析了背景光强对强度涨落的影响。结果表明: 焦距和背景光强的变化对计算关联成像成像质量影响不大,解决了热光关联成像中两光臂不等形成的散焦造成成像质量下降的问题,并且该成像只用一个无空间分辨能力的探测器就能完成高分辨率成像,降低了对探测器分辨能力的要求,避免了光通量在维度上的分配,提高了信噪比,且无需成像透镜,该成像方式非常适合用于极弱背景下的成像探测。

Conventional optical imaging require the image plane at the focal plane of the imaging lens group to get the maximum flux. So the focal length has great impact on imaging quality. In order to investigate the influence of focal length on quality of computational ghost imaging, the experiment of computational ghost imaging was constructed, and the probability density of the measurement of bucket detector was utilized to analyze the results of computational ghost imaging with different focal length and background light. The results show that the variation of focal length and background light have little effect on the quality of computational ghost imaging, which solve the problem that the defocus lead to the deterioration of quality caused by the inequality of two optical path in traditional ghost imaging. Computational ghost imaging can be realized without imaging lens and only using a bucket detector, thus avoiding the allocation of flux on the pixel dimension as well as improving the signal-to-noise ratio. Therefore, computational ghost imaging is very suitable for imaging detection under the extremely weak background.