Grating-based phase difference wavefront sensor

Abstract

The invention discloses a grating-based phase difference wavefront sensor which comprises a grating, a lens, a spectroscope, a CCD (Charge Coupled Device) imaging detector, a computer and the like, wherein a parallel light beam containing wavefront distortion is directly irradiated onto the surface of the grating; and the light beam is divided into multiple beams of light with different intensities and same phase after being transmitted by the grating and is imaged on a CCD photosensitive surface by the lens. According to two or multiple grating diffraction spots, the light intensity distribution of the spots can be more accurately calculated by a corresponding algorithm. According to focal plane and defocusing surface light intensity distribution, the computer can restore to obtain wavefront distortion information to be detected. In the grating-based phase difference wavefront sensor, the CCD imaging detector can be used for collecting the high-frequency ingredient of the light intensity distribution which can not be measured in the common condition, the detection precision of the phase difference wavefront sensor is effectively improved, and the phase difference wavefront sensor has obvious advantages in the fields of optical detection, adaptive optics, high-resolution imaging and the like.

Description

technical field [0001] The invention relates to a phase difference-based wavefront sensor, in particular to a grating-based phase difference wavefront sensor. Background technique [0002] Due to its simple structure, no special requirements on the light source and high measurement accuracy, the phase difference wavefront sensor is used as a wavefront sensor in the field of adaptive optics. Gonsalves R A in "Wavefront sensing by phase retrieval", in Applications of Digital Image Processing III, Proc. SPIE, vol.207, 1979 and "Phase retrieval and diversity in adaptive optics" Opt Eng, Vol.21, 829-832, 1982 In the two articles, it is proposed to add a defocus aberration of known size to the wavefront to be measured, and accurately measure the focal plane light intensity distribution and multiple light intensity distributions located on different defocus planes. Based on the least squares estimation, the GS The iterative algorithm accurately restores the distorted wavefront in ...

AI Technical Summary

Problems solved by technology

Since the output image of the CCD imaging detector has certain noise, and the CCD imaging detector has a relatively sensitive light intensity range, when the light intensity of the spot is weak, it is affected by the signal-to-noise ratio of the output image and the sensitivity of the CCD imaging detector. Affected by the CCD, the CCD cannot obtain the light intensity distribution information of the diffraction spot with a higher order, the high-frequency information of the restoration aberration will be lost, and the detection accuracy will be affected to a certain extent

If the distorted wavefront to be measured contains not only large-scale, slowly changing low-spatial-frequency optical aberrations, but also high-spatial-frequency aberrations caused by optical component processing, the distorted wavefront will cause focal plane position, defocus The energy distribution of the light spot at the surface position is relatively scattered, the distribution of advanced diffraction components is complex and the light intensity is weak, and it is difficult to accurately collect the light intensity distribution image

At present, the common CCD imaging detector has a small detection dynamic range. When the spot light intensity at the focal plane of the lens is weak, the detected light intensity distribution information is seriously affected by noise. When the spot light intensity at the focal plane is strong, The output image of the CCD imaging detector is easily saturated, and the detected light intensity distribution error is relatively large, which leads to the inability of the traditional phase difference wavefront detection method to accurately restore the measured wavefront distortion information

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