A Surface Encoder with Dual Sine-grids

Abstract

This paper describes a surface encoder for two-dimensional position measurement, which consist of a 2D sinusoidal grid (target grid) and a 2D slope sensor used to read the local slopes of the grid surface. The new type of 2D slope sensor employs a transparent sine-grid on a glass plate which is fabricated by UV replication with the same amplitude and wavelength as the target grid. Compared with conventional surface encoder, the improved sensor which has the transparent sine-grid has the advantage of high S/N ratio. The fabrication of the transparent sine-grid and some measurement results are presented.