Surface testing device and method employing partially coherent light field type diffusion reflection screen

Abstract

The invention discloses a surface testing device and method employing a partially coherent light field type diffusion reflection screen. A partially coherent light source emits partially coherent light beams and the light beams are modulated by a spatial light modulator and enter a quartz flat plate. The quartz flat plate diffuses and reflects the modulated partially coherent light beams to a to-be-tested element on an experimental platform and the partially coherent light beams are reflected by the to-be-tested element. The partially coherent light beams carrying surface information of the to-be-tested element is reflected to an imaging objective lens. After image formation, the partially coherent light beams are received by a target face of a detector. The detector inputs collected phase distribution information into a computer and the computer performs light field analysis computation. The surface shape of the to-be-tested element is obtained through inversion by utilizing the obtained phase distribution. The device and method provided by the invention has advantages that light diffused and reflected by the quartz flat plate can have both coherence and controllability at the same time by utilizing the coherence of the partially coherent light source and by combining light intensity modulation action of the spatial light modulator.

Description

technical field [0001] The invention belongs to the surface shape detection technology of optical elements, in particular to a surface shape detection device and detection method using a partially coherent light field type diffuse reflection screen. Background technique [0002] The phase measuring deflectometric method (PMD) was first proposed in 2004 by Markus C. Knauer of the University of Erlangen-Nuremberg and others. The basic idea is to project a modulated light field to the surface of the measured element through the diffuse reflection screen, and use the CCD to receive the reflected light in the direction of light reflection, because the fluctuation of the surface of the object will cause the phase of the light field reflected on its surface Change, then by measuring and calculating the amount of change in the phase of the light field to obtain the topography of the object surface. [0003] Compared with other measurement methods, the main advantages of this method...

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to provide a surface shape detection device and detection method using a partially coherent light field type diffuse reflection screen, using phase deflection technique in the surface shape detection of high-precision large-diameter optical elements, which solves the problems in the existing methods. The low flatness of the LCD display limits the measurement accuracy

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