Design and fabrication of a crossed grating with multiple zero-reference marks for surface encoders

We propose a new crossed grating with multiple zero-reference marks in the area of crossed grating structures. The fabrication process and the performance tests are introduced in this paper. The experiment results show that the diffraction efficiency of the crossed grating only reduces from 14% to 12% on account of the zero-reference marks. The repeated positioning accuracy of the zero-reference marks reaches 15.1 nm.