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Surface measurement based on chessboard-shaped 2-D Ronchi grating method.

A method for surface profile measurement using a chessboard-shaped 2-D Ronchi grating is proposed. The gradients in two orthogonal directions of the measured surface can be obtained simultaneously using a chessboard-shaped 2-D Ronchi grating, so that it is possible to reconstruct the surface profile by means of only one Ronchigram with high accuracy. The measuring principle and the design of the chessboard-shaped 2-D Ronchi grating are described. Measurements of both stationary and varying surfaces using an instrument constructed on the basis of the method were conducted with satisfactory results.