Read/Search this Article The cross grid encoder is an optical
diffraction grating type encoder to measure two-dimensional
position of a optical head by using a grid plate where grids are
aligned orthogonal to each other. The cross grid encoder can be
applied to measure two-dimensional motion errors of high-
precision and ultra-precision machine tools, such as the
straightness error or the squareness error. As a basis to
establish a methodology to measure evaluate motion accuracy of
high- and ultra-precision machine tools by using the cross grid
encoder, this paper presents a self-calibration scheme of a
measurement error of the cross grid encoder caused mainly by the
misalignment of grids. The measurement error corresponding to
the location on the grid plate is calibrated by comparing three
measurements taken with different orientation of the grid plate.
It is experimentally validated that the measurement error of the
cross grid encoder is reduced by about 85% at maximum by
applying the self-calibration and th