| dc.description.abstract | How to connect the result of tolerance analysis to image quality is a challenging problem for an imaging system. Because of the image quality is affected by imaging lens and image restoration in a phase coding image system, so this is much more difficult for such kind of imaging system. Although some studies have shown the performance of depth of field for a phase coding imaging system will not be affected by centering error, but variation of depth of field which causing form surface error on phase coding element is not considered yet. And most of studies focus on the properties of transfer function of phase coding element, and ignore the transfer function of image restoration itself. In order to understand the effect of surface error on phase coding element, we present a method which combining similarity of point spread function, imaging simulation, image restoration and image metric for first time to analysis the variation of depth of field. And the tolerance analysis of cubic phase mask is discussed which a spoke type surface error is included
In Chap. 1, we introduce the basic working principle of phase coding imaging system and summarize results of current related researches for it. In Chap. 2, the theories of cubic phase coding and image restoration are both described. In Chap. 3, the detail calculation produces of similarity of point spread function, imaging simulation, image restoration and image metric are described. In Chap.4, the present method which considering the effects of spoke type surface error in phase coding element is considered. And effectiveness of similarity of point spread function and an image metric (peak signal to noise ratio, PSNR) are discussed. Finally, simulation and experiment results for a cubic phase coding element are both presented also.
We find that, for a phase coding element which existing surface error, similarity of point spread function can not represent the performance of depth of field; but image metric PSNR can. And also we find if the peak to valley for a phase coding element can be better than 0.1λ, the performance of depth of field will not affected by numbers of spoke ring. If some 10 to 100 numbers of spoke ring are existed, the peak to valley of surface error can be released form 0.1λ to 0.25λ or even 0.50λ. So by using our method, the required accuracy of phase coding element and the performance of depth of filed in phase coding imaging system can be determined.
Finally, we also point out the potation applications and prospect of future research items.
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