Expanding the dynamic range of the measuring system by implementing the phase triangulation method.

This article discusses approaches for expanding the dynamic range of measuring systems by implementing phase triangulation methods and structured illumination. These systems are designed for the high-precision measurement of the geometric parameters of complex profile products with arbitrary light-scattering surface properties. A method for expanding the dynamic range of thea measuring system is proposed, which is based on the automatic adjustment of the photodetector exposure duration, redundant collection of experimental data, and complex regression analysis. The results of experimental studies on the efficiency of the proposed method are presented. It has been demonstrated that the classical approach to interpreting images obtained using a photodetector with a fixed exposure duration almost always causes a large measurement error in the geometric parameters of a surface with a wide range of light-scattering properties. At low exposure values, the error in measuring the geometric parameters of the surface increases in the dark area, where the signal level is substantially weaker compared to the light areas of the measured surface. At high exposure values, the error in measuring the geometric parameters of the light area of the surface increases because the signal is outside the dynamic range of the photodetector. For the measured geometric parameters of surfaces with different light-scattering properties, the use of a photodetector with an extended range enables achieving a measurement error less than or approximately equal to the error of a measuring system containing a photodetector with a fixed exposure. Expanding the dynamic range simplifies automated measurements because there is no need to further optimize the photodetector parameters for the light-scattering properties of the surface of the measured object. [ABSTRACT FROM AUTHOR]