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

Abstract

The invention discloses a method for measuring focal length and equivalent f-number with a grating type wavefront curvature sensor. In the method, a defocused wavefront with the focal length to be measured is generated by transmission or reflection, and the defocused wavefront is incident into the grating type wavefront curvature sensor, and the grating type wavefront curvature sensor is used to detect the defocused light spots on the two defocused surfaces , measure the diameter d1 of the front defocused spot and the back defocused spot d2, and obtain the equivalent focal length fg of the defocus grating and the focal length fi of the short focal length lens according to the design parameters of the grating wavefront curvature sensor; ③. Calculate the diameter d1 of the two defocused spots The normalized difference S between d2 and d2; ④. Determine the positional relationship of the obtained two defocused light spots, and calculate the focal length or equivalent f-number through different formulas. The invention has the advantages of high measurement accuracy, wide application range, low cost and the like.

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

[0008] 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.

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