A device and method for measuring modulation transfer function

Abstract

The invention discloses a device and method for measuring modulation transfer function. The resolution plate of the device is placed on the bracket of the collimator, located in the center of the cross-section of the collimator, and its outer frame is a square, and the graphics on the resolution plate are concentric, bright and dark annular stripes with different spacing and width. . The measurement method takes the azimuth θ of the required measurement direction as the center, and continues the micro angles in the left and right directions of the azimuth as the processing area, and the spatial direction and spatial frequency of the resolution plate in the processing area The image of the stripe area is measured, and after data processing, the maximum and minimum values ​​of the gray value of the image are counted to obtain the contrast of the image within the range of the required measurement direction, and the value of the modulation transfer function is calculated. The invention adopts the annular resolution pattern of the resolution plate, not only can measure the MTF value in the horizontal and vertical directions of the photoelectric instrument, but also can measure the MTF value in any spatial direction.

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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