Optical freeform surface interference detection system

Abstract

The invention discloses an optical freeform surface interference detection system. A point light source array is adopted to generate a multi-field-of-view sloped wavefront to illuminate a measured optical freeform surface, the point light sources located on the optical axis are always lit up as reference light, and according to the phase-shifting interferometry, subregion wavefront data are recovered from a multi-field-of-view interferogram; a standard spherical surface is used for calibrating the positional relation between CCD (Charge Coupled Device) pixels and the multi-field-of-view interferogram, the position of the multi-field-of-view interferogram is shifted when the optical freeform surface is measured, and wavefront slope information is obtained from the offset; and according to the slope information and multi-field-of-view subregion wavefront data, the surface form information of the measured surface is reconstructed. A controllable point light source array-lighting scheme is generated according to the characteristics of the measured surface, and the system can cover a variety of test objects (convex-concave aspheric surfaces and freeform surfaces). The invention overcomes the defects of simplicity and high cost of the conventional freeform surface detection method, the defect of great error caused by the non-common path in the conventional detection method and the defect of high displacement precision requirement of the subaperture method.

Description

technical field [0001] The invention relates to a Fizeau-type common optical path interference measurement device, in particular to a device used for surface quality inspection of optical aspheric surfaces and optical free-form surfaces. Background technique [0002] In recent years, the superiority of optical free-form surfaces has attracted widespread attention of scientific and technical personnel, and they have tried to use free-form surfaces to improve the performance of optical systems. It is generally believed that optical free-form surfaces will have a revolutionary impact on the quality and miniaturization of optical systems, but no matter Neither the production cost nor the processing accuracy can compare with the traditional aspheric surface. The precise detection of surface shape is the bottleneck technology restricting the development of free-form surface technology. [0003] The processing of optical free-form surfaces is divided into three stages: milling, gri...

AI Technical Summary

Problems solved by technology

Generally, the first and second stages use a three-coordinate machine and a surface profiler for inspection respectively. The third stage requires the highest precision. The polished optical free-form surface must take into account the ultra-high precision requirements for measurement and the inspection process. The contradiction between measurement accuracy and measurement range makes traditional contact measurement unable to meet the requirements

At present, different methods have been proposed for optical free-form surface detection technology at home and abroad, but there are problems: the measurement method is slow and the flexibility is not enough

This scheme can detect both rotationally symmetric aspheric surfaces and non-rotationally symmetric aspheric surfaces, and has the application prospect of detecting free-form surfaces. However, the interferometric system uses an improved Tieman Green type, and many optical elements are introduced into the interferometer reference arm. The optical path is complicated. , there are many error sources, which is not conducive to improving the detection accuracy

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