Color polarization confocal measurement method based on ring-shaped structured light

Color confocal displacement measurement (CCM) is a noncontact optical measurement method widely used for nondestructive testing of object surface contours, but the rapid development of manufacturing technologies has imposed stricter requirements on CCM, including integration, higher precision, and higher measurement speeds. Traditional refractive CCM structures are bulky and cannot be integrated, whereas diffractive CCM structures hinder high-speed measurements because of nonlinear dispersion. This article proposes a color polarization confocal measurement method based on ring-shaped structured light (CCRSL), combining binary optics with polarization to achieve integration and high-speed measurements. In addition, two axicon lenses are used to generate ring-shaped structured light and eliminate optical energy loss in the polarization folding system. Modeling is conducted using ZEMAX software and numerical analysis methods to simulate and analyze the CCRSL performance. The resulting linear determination coefficient R² is 1, the measurement range is 2 mm, the measurement precision is 0.29 um, and the resolution reaches 80 nm. Compared with the traditional method, the length of CCRSL is reduced by 72 % and the resolution is increased by 2.5 times.