Design of Linear Dispersive Objective for Chromatic Confocal Displacement Sensor

In this study, the working principle of the chromatic confocal displacement sensor and the conditions of linear axial dispersion were applied for the optimal selection of three kinds of glass materials, namely N-KZFS11, N-SF66, and N-PK52A, which were combined with the theory of aberration to design the initial structure of a linear dispersive objective composed of three single lenses and two double cemented lenses. Then, the Zemax software was used to optimize the initial structure of the dispersive objective and analyze its tolerance. The results indicate that within the wavelength range from 150 nm to 650 nm, the blur spot at each wavelength is much smaller than the Airy spot. The measurement range of the dispersive objective is up to 1.05 mm, the linear determination coefficient R-2 between the axial dispersion and wavelength is 0.997, and the theoretical resolution could reach 105 nm.