Study Of Relationship Between Spatial Resolution Of Ring Coded-aperture Images And The Width Of Ring In ICF

In ICF(inertial confinement fusion) experiments, RAM(ring coded-aperture microscope) is an important imaging equipment of X-rays. In this paper, we will study the relationship between spatial resolution of images and the width of ring. Traditionally, spatial resolution is limited by the width of ring. While considering the reversibility of imaging system, we propose that original image may be restored even if ring width is bigger than original size. That is to say, increasing the width of ring within certain range will not influence image resolution. The proposition is true or not? What is the limit the ring width can be widened? We focus our research on these questions and give answers to them in this paper.in current study of RAM, geometrical imaging is considered and optical diffiaction is ignored, which is applicable to image restoration study but not to study of image resolution and other ultimate questions. So first, we combine optical diffraction with the coded-aperture, study imaging theory of RAM when diffraction is considered. We get the system PSF formula and carry it out in computer; last, discuss the applicability of wiener-filter. This work is the base of study of relationship between ring coded-aperture images resolution and ring width.The results through a lot of simulate experiments on different kinds of original stripe images show: when the ring width increases to 10 or more times of original size at SNR(signal-noise ratio) =-10dB, original image can still be restored in good quality. The results of actual ICF restoration experiments are evidences that the simulate results are accurate. So, we can conclude that in ICF experiment, the ring width doesn't have to be limited by original size, it can be widened to 10 or more times of the limit even at low SNR, which is helpful for decreasing difficulty of fabrication of the ring apertures and increasing SNR in ICF experiments.