Cross wire pattern unit, reticle and method for measuring amplification factor of back projection light path

Abstract

The invention relates to a cross wire pattern unit, a reticle, a method for measuring the amplification factor of a back projection light path and a method for establishing an MTF curve two-dimensional coordinate graph of a measured lens by adopting the cross wire pattern unit. The cross wire pattern unit comprises a cross wire pattern arranged in the middle of a cross wire pattern unit, a positioning point is arranged in each of four quadrants divided by the cross wire pattern, and the connecting line of the positioning points in every two adjacent quadrants is parallel to one line of the cross wire pattern. Due to the fact that the positioning points are arranged in the cross wire pattern unit, the amplification factor of a measured conjugate light path can be conveniently determined bymeasuring the distance between the positioning points; according to the method for measuring the amplification factor, the problem of errors caused by the fact that the amplification factors of the to-be-measured lenses of the same batch are the same by default in on-line measurement of the MTF can be solved so that the result calculation of the MTF can use the real amplification factor instead ofthe amplification factor values preset in batches, and the measurement precision is improved.

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 back 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 back projection, place a reticle engraved with a specific pattern and a backlight on the image plane of the lens under test, place multiple image sensors on the object plane, and obtain the multiples of the lens under test through focus adjustment and image calculation. 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 of the back projection measurement MTF includes such as figure 1 The infinite distance conjugate...

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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