OPTICAL DISPLACEMENT GAUGE AND SURFACE SHAPE MEASURING DEVICE THEREWITH, DISPLACEMENT MEASURING METHOD AND SURFACE MEASURING METHOD THEREWITH, AND DISPLACEMENT MEASURING METHOD AND STORAGE MEDIUM WHICH CAN BE READ BY COMPUTER STORING PROGRAM TO ALLOW COMPUTER TO EXECUTE DISPLACEMENT MEASURING METHOD OR SURFACE SHAPE MEASURING METHOD

摘要

PROBLEM TO BE SOLVED: To widen the measuring range and make the scanning speed high. ;SOLUTION: The surface shape of an object 13 to be measured is obtained by X coordinate shown by moving quantity of a linear encoder 4b and Z coordinate in which the moving quantity of the linear encoder 4a and a relative changing quantity between an optical displacement gauge 1 and are the object 13 are added. In the measurement of the relative changing quantity, a nonlinear range as wall as the linearity range of differential output S in the gauge 1 is utilized. This range is approximated by a secondary or later polynominal function, dz=A₂.S₂+A₁.S+A₀ (dz: relative changing quantity). Coefficients A₂, A₁ and A₀ are functions of tilt angle of the surface of the object 13, A₂=A₁ () and A₀=A₀ (). First, the respective coefficients are acquired from the obtained tilt angle , and the coefficients are substituted into the polynominal functions to convert the differential output S into relative changing quantity dz. Thus, the measuring range can be widened and the scanning speed can be made higher.;COPYRIGHT: (C)1998,JPO