The prism turning theorem as first put forward in China describes the directional conjugate relation between the object and the image space, being applicable to afocal systems.
棱镜转动定理是我国首先提出的，实际上此定理描述的是物、象空间方向共轭关系，适用于无光焦度光学系统。
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The restored image obtained by using the space domain conjugate gradient algorithm is too smooth and loses some information about the edge detail.