Littrow 3D measurement based on 2D grating dual-channel equal-optical path interference
Yunfei Yin, Lin Liu, Yu Bai, Jirigalantu Jirigalantu, Hongzhu Yu, Bayanheshig Bayanheshig, Zhaowu Liu, Wenhao Li
Abstract
We propose a 3D measurement method based on 2D grating dual-channel and Littrow equal-optical path incidence to detect the 3D displacement of a 2D grating in the X -, Y -, and Z -directions. The 2D grating is combined with the Littrow incidence method and a turning element to cause the Littrow diffracted light with frequency f 1 to interfere with the reference light at frequency f 2 , and the displacement data in the X -, Y -, and Z -directions are obtained using the separation-dual-channel phase decoupling algorithm. A corresponding test experimental platform is constructed, and linear error evaluation and step error evaluation experiments are performed to determine the displacements in the X -, Y -, and Z -directions. The results obtained show that all linearity errors are within ±60 nm in the 10 mm measurement ranges in the X -, Y -, and Z -directions, and the test resolution is within ±5 nm. The proposed method can thus realize nanoscale synchronous measurement of X -, Y -, and Z -direction 3D displacements.