The method of measuring the magnification of the back projection optical path and the method of establishing the mtf curve

Abstract

The invention relates to a cross-hair pattern unit, a reticle, a method for measuring the magnification of a reverse projection optical path, and a method for establishing a two-dimensional coordinate diagram of an MTF curve of a measured lens by using the cross-hair pattern unit. It includes a reticle pattern set in the middle of the reticle pattern unit, and there is an anchor point in each of the four quadrants divided by the reticle pattern, and the connection lines of the anchor points in two adjacent quadrants are parallel to the reticle. One of the lines of the pattern. In the present invention, since the positioning point is provided in the crosshair pattern unit, it is convenient to determine the magnification of the conjugate optical path measured by measuring the distance of the positioning point; the method for measuring the magnification can solve the problem of the same batch of default MTF online measurement. The same magnification of the measurement lens brings the problem of error, so that the calculation of the MTF result can use the real magnification instead of the batch preset magnification value, which improves the measurement accuracy.

Description

technical field [0001] The invention relates to the field of optical detection, in particular to a crosshair pattern unit, a reticle, a method for measuring the magnification of a reverse projection optical path, and a method for establishing a two-dimensional coordinate diagram of an MTF curve of a lens under test by using the crosshair pattern unit. Background technique [0002] Using the optical path of reverse projection, place a reticle and a backlight with a specific pattern on the image surface of the lens under test, and place multiple image sensors at the position of the object surface. Point MTF data is currently the main way to measure lens MTF online. The MTF characteristics of the optical system can be obtained by software analysis of the images obtained by the image sensor. The optical path for back-projection measurement of MTF includes such as figure 1 The infinite conjugate optical path shown, and as figure 2 The finite-distance conjugate optical path sh...

AI Technical Summary

Problems solved by technology

Compared to the other two patterns, such as image 3 The reticle pattern shown has the advantage of being simpler in content and is more versatile, but also has the disadvantage of not being able to measure the magnification of the conjugate optical path

The magnification of the conjugate optical path is the key parameter for converting the result calculated by the algorithm into the MTF characteristic of the image. When it cannot be measured in the cross-hair screen, the online measurement MTF can only calculate the MTF according to the fixed magnification input in advance. The default The magnification of the tested lenses of the same batch is the same, but there are differences in reality, so there is an error in the measurement of MTF

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