Polarization-folding ultra-wide spectral chromatic confocal line displacement sensor based on a binary lens

Abstract

Chromatic confocal line displacement sensors are widely used for non-contact optical measurement. With the development of industrial manufacturing technology, the requirements of high precision, miniaturization, and high-velocity measurements have become more stringent. The traditional structure uses a complex dispersive objective for axial dispersion, which has high accuracy, but the miniaturization process is hindered. Furthermore, the axial dispersion linearity of Chromatic confocal sensors based on diffractive elements is poor, which cannot be applied to high-speed measurement scenarios. In this paper, a polarization-folded ultra-wide spectral chromatic confocal line displacement sensor based on binary lens (PFCCB) is proposed. Leveraging the dispersion ability of a binary lens, a wide spectrum of 400–1000 nm is spread along the axis. The polarization-folding lens group can correct the dispersion curve of the binary lens so that the axial dispersion curve of the system is strictly linear. The optical performance of the polarization-folded lens group is equivalent to that of the traditional lens group, but the volume of the polarization-folded lens group is smaller, which aids in the miniaturization of the sensor. The PFCCB sensor is modeled using ZEMAX software, and the performance of the PFCCB sensor is simulated by numerical analysis. The results show that the linear determination coefficient R2 of the PFCCB sensor is 1, the total optical length is 5.9 mm, the measuring range is 2.5 mm, and the system resolution reaches 100 nm. The PFCCB sensor has the characteristics of high precision, miniaturization, and high-velocity measurement.