Method for measuring focus and equivalent f coefficient using optical grating type wave-front curvature sensing unit

Abstract

The invention discloses a method using grating wave front curvature sensor to measure focus and equivalent f number, the steps being: firstly, using reference beam to calibrate the grating wave front curvature sensor; placing the measured device in the optical path, and through the transmission or reflection way to generate the dispersing focus wave front of the measured focus, and the dispersing focus wave front incidents into the grating wave front curvature sensor and using the grating wave front curvature sensor to detect the focus away spot of two focus away surfaces, and measuring diameter d1 of the front focus away spot and the rear focus away spot d2, and according to the grating wave front curvature sensor design parameters, obtaining focus away grating equivalent focal length fg, and the short focal length lens focal length fl; calculating the normalized difference S of the two defocus spot diameter d1 and d2; judging the two defocus spots position relation, and through various formulas, respectively calculating the focal length and equivalent f number. The invention has advantages of high measurement precision, wide application range, and low cost.

Description

technical field [0001] The invention mainly relates to the field of optical detection, in particular to a method for measuring focal length and equivalent f-number with a grating type wavefront curvature sensor. Background technique [0002] In the prior art, there are many methods for measuring the focal length of a convex lens or a concave mirror. It can be measured by direct imaging, and its focal length can be calculated by measuring the object distance and imaging distance. It can also be measured by the astigmatism method. In addition, the radius of curvature of the surface shape of the lens or reflective spherical mirror can be measured by interferometry to obtain their focal length. There are many ways to measure the thermal lens in the solid laser gain medium. The simplest method is to pass the probe beam through the gain medium and measure the movement of the focus position along the axis. This method includes a moving device and cannot measure the instantaneous th...

AI Technical Summary

Problems solved by technology

[0007] In the past, the beam splitter method and the vibration thin film modulation mirror method were used to realize the wavefront curvature sensing technology. These two methods have defects such as high manufacturing process requirements, pseudo simultaneous measurement, and system instability.

Images