Method of detecting surface shape of reflection element based on dual-frequency orthogonal grating projection

Abstract

The invention provides a method of detecting the surface shape of a reflection element based on dual-frequency orthogonal grating projection. When the method is used to detect the reflection optical surface shape, basic devices comprise a CCD sensor, a to-be-detected element, an LCD display and a computer. The LCD display sequentially displays phase-shifting fringe patterns generated by computer coding, and the CCD receives and obtains the deformed fringe patterns reflected through the surface of the to-be-detected element. If a physical grating and a mechanical device are used for phase shifting in a measuring system, switching in a vertical grating and a horizontal grating needs to be carried out, and a corresponding phase shifting amount is further completed. In order to avoid grating switching in the two directions and realize the accurate phase shifting amount, a dual-frequency orthogonal grating phase shifting method based on least squares iteration is proposed, the dual-frequency orthogonal grating is applied to phase deflectometry, no grating needs to be replaced in a measuring process, an accurate phase shifting amount is not needed either, and phase distribution in two directions can be acquired at the same time. The method has the beneficial effects of being high in measuring result accuracy and applicable to high-accuracy three-dimensional surface shape measurement.

Description

technical field [0001] The invention relates to the technical field of optical element plane detection, in particular to a method for detecting the surface shape of a reflective element by phase measurement deflectometry based on dual-frequency orthogonal grating projection. Background technique [0002] The detection object of optical surface shape detection technology can be roughly divided into diffuse reflection surface and mirror surface according to the relationship between the smoothness of the surface to be measured and the wavelength of the light source. Since the light intensity signal of the diffuse reflection surface can be received from any angle, the surface shape detection technology for the diffuse reflection surface is more flexible, and related technical detection technologies are widely used in the field of machine vision, including phase measurement profiling and Moiré stripe method. Mirror and mirror-like objects have become the focus and difficulty in ...

AI Technical Summary

Problems solved by technology

However, the traditional phase measurement deflection technique requires fringe projections in the vertical and horizontal directions, and the phase information in the two orthogonal directions is extracted by a phase shift algorithm, which is a complex and time-consuming process.

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