Abstract: A method for figure correction of an optical element includes forming a masking layer on a surface of the optical element. The optical element has thinning regions and non-thinning regions. The masking layer is patterned to form masking regions and non-masking regions, and the masking layer is positioned relative to the optical element in such a manner that the masking regions corresponds to the non-thinning regions of the optical element and the non-masking regions corresponds to the thinning regions of the optical element. The method further includes performing reactive ion etching on the optical element provided with the masking layer so as to etch the thinning regions of the optical element to reduce a thickness of the thinning region.

Abstract: A method for figure correction of an optical element includes forming a masking layer on a surface of the optical element. The optical element has thinning regions and non-thinning regions. The masking layer is patterned to form masking regions and non-masking regions, and the masking layer is positioned relative to the optical element in such a manner that the masking regions corresponds to the non-thinning regions of the optical element and the non-masking regions corresponds to the thinning regions of the optical element. The method further includes performing reactive ion etching on the optical element provided with the masking layer so as to etch the thinning regions of the optical element to reduce a thickness of the thinning region.

Abstract: The application relates to a method and device for removing a scanning bed from a CT image. The method includes steps: reading a three-dimensional CT image, counting an amount of kernels in a CT apparatus and initializing sub-algorithms through a main thread of an image processing apparatus; extracting two-dimensional scanning images from the input three-dimensional CT image, automatically allocating the two-dimensional scanning images to kernels through the main thread of the image processing apparatus by sharing a memory, thereby realizing a multi-thread parallel processing to perform a bed removing operation on the two-dimensional scanning images; and ending the parallel processing and outputting a three-dimensional CT image without scanning bed information through the image processing apparatus. The method of the disclosure is very effective and accurate.