Device and method for measuring modulation transfer function

Abstract

The invention discloses a device and a method for measuring modulation transfer function. A resolution panel of the device is arranged on a support of a collimator and located at the central position in the cross-section of the collimator; the outer frame of the resolution plate is square, patterns on the resolution plate are ring-shaped strips which are concentric and alternately dark and bright with different spacing and widths. The measurement method comprises the following steps: azimuth angle theta of the direction which is needed to be measured is served as the center; micro angle is continued at the left and right directions of the azimuth angle to be served as a processing area; ring-shaped strip area image of space direction and space frequency of the resolution plate in the processing area is measured; through data processing, the maximum value and the minimum value of the gray value of the image is worked out, thus obtaining the contrast ratio of the images in the range of the direction which is needed to be measured and figuring out the modulation transfer function value. In the invention, ring-shaped resolution images of the resolution plate is employed, so that not only MTF value of a photoelectric device in the horizontal direction and the vertical direction is obtained, but also MTF value in any space directions can be measured.

Description

technical field [0001] The invention relates to a method and a device for measuring the modulation transfer function of optical devices or photoelectric instruments. Background technique [0002] The modulation transfer function (MTF) reflects the degree of image contrast attenuation during the imaging process at different spatial frequencies, and is a physical quantity used to evaluate the imaging performance of optoelectronic instruments and optical lenses. [0003] Due to the different measurement principles, traditional instruments can only measure the modulation transfer function of optical devices or optical instruments alone. The data processing of the traditional method requires time-frequency conversion, which is restricted by data processing overhead and precision. The measurement method without data time-frequency conversion has high requirements for sample design and production. When the graphic spatial frequency of the resolution board is high, measurement erro...

AI Technical Summary

Problems solved by technology

[0006] This technical solution uses a resolution board with a rectangular change in the gray scale of the graphic to replace the resolution board with a sinusoidal change in the gray scale of the graphic that is difficult to design and process, and realizes the measurement of the modulation transfer function of the camera, but there are still two deficiencies in the following aspects: (1) The spatial resolution board contains multiple resolution graphics from low frequency to high frequency. When the spatial frequency increases, the number of pixels corresponding to the imaging range of a single resolution fringe to the detector image plane decreases.

The inaccurate registration of the fringe image and the image detector pixel will cause measurement errors, making the measured value of MTF smaller than the actual value

(2) This method can only measure the MTF values ​​in the horizontal and vertical directions, and cannot measure the MTF values ​​in other directions

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