A method for measuring lens focal length based on computational holography

Abstract

The invention discloses a method for measuring the focal length of a lens based on calculation holography. The method includes the following steps: designing a CGH; Radius parameter, make CGH; acquisition of background wavefront, use plane interferometer, measure 0-order wavefront of CGH multiple times, take the average as background wavefront; acquisition of distance between lens and CGH, use plane interferometer, measure multiple times The wavefront of the lens, the distance between the lens and the CGH is measured at the same time, the background wavefront is subtracted from each transmitted wavefront, and the relationship between the defocus amount-spacing is calculated to obtain the optimal distance; the focal length of the lens is obtained, and the first-order curvature radius of the CGH is measured, according to The first-order radius of curvature of the CGH and the distance between the lens and the CGH give the focal length of the lens. The invention realizes the high-precision detection of the focal length of the telephoto lens, shortens the overall detection optical path length, and improves the anti-environmental interference capability.

Description

technical field [0001] The invention belongs to the technical field of lens focal length detection, and more specifically relates to a method for measuring the focal length of a lens based on computational holography. Background technique [0002] With the development of aviation, aerospace, and astronomy and other fields, the requirements for the quality and precision of the optical system have been increased. In order to ensure the imaging quality of the optical system, it is more and more important to accurately measure the focal length of the optical lens. Large aperture and long focal length lenses are widely used in national large-scale optical devices such as inertial confinement fusion and astronomical detection systems. The focal length is an important indicator of this type of component, and the mismatch between the focal length and the design will directly affect the beam quality and imaging quality. [0003] The existing optical lens focal length testing methods...

AI Technical Summary

Problems solved by technology

Among them, the knife-edge method and the Hartmann method require a long space, and the results are greatly affected by the subjective influence of the inspectors; the Moiré deflection method uses the method of Moiré fringe interpretation, which is obviously affected by the environment and difficult to trace the source; although the combined lens method The length of the detection optical path is greatly shortened, but it still cannot solve the problem of poor anti-interference ability inherent in the interferometry method, and the distance between the measured mirror and the standard mirror cannot be accurately measured as a key parameter

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