A Method for Obtaining Optimal Parameters of Phase Mask Applied in Wavefront Coding System

Abstract

The invention relates to a phase mask plate optimal parameter acquisition method applied to a wavefront coding system. The method comprises the following steps that (1) three optimization objectives expected to be achieved are established, wherein the three optimization objectives expected to be achieved are OTF defocusing invariability, MTF defocusing invariability and PTF defocusing invariability; (2) Fisher information is calculated according to a defocused MTF, a defocused PTF and a defocused OTF respectively; (3) an objective function is established through weighting according to the Fisher information corresponding to the three objectives to be optimized; (4) a phase mask plate optimal parameter is acquired according to the objective function established in the step (3). The phase mask plate optimal parameter acquisition method is applied to the wavefront coding system, and the stability of the defocused PTF of the system can be improved through the method.

Description

technical field [0001] The invention belongs to the field of optics, and relates to a method for acquiring parameters of a phase mask, in particular to a method for acquiring optimal parameters of a phase mask applied to a wavefront coding system. Background technique [0002] Extending the depth of field of optical imaging systems has always been a research hotspot in the academic circles. Reducing the relative aperture of the system can achieve the effect of extending the depth of field, but it will seriously lose luminous flux and resolution, so it is not practical. Since the mid-1980s, although various methods have been proposed to extend the depth of field of the imaging system, it was not until Dr. E.R. Dowski and Professor Cathey of the University of Colorado in the United States proposed the concept of wavefront encoding in 1995 that the depth of field extension had no effect. A real breakthrough. [0003] By adding a cubic phase plate on the aperture plane, entran...

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Problems solved by technology

Excessive reduction of MTF will cause the loss of the signal-to-noise ratio of the intermediate blurred image, which will directly affect the restoration filtering effect, resulting in a decline in the restoration quality of the image.

[0012] It can be seen that it is not advisable to rely solely on the increase of the modulation factor to achieve the defocus stability of PTF, and the existing research has also shown that the insensitivity of PTF to defocus should be close to or even reach the level of defocus MTF is very difficult

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