Patent ID: 7188046

Claim:
A form measuring device comprising: a measuring section for combining two out of three surfaces to be measured substantially in parallel to each other as a pair in a specific pattern, and respectively measuring a space therebetween at a plurality of sampling points; a function value setting section for setting form-function values, which indicates distances from reference planes respectively set for each of said surfaces to be measured to said surfaces to be measured; a simultaneous equation deriving section for deriving simultaneous equations for a pair of said surfaces to be measured having a specific pattern assuming that an surface spacing between said surfaces to be measured placed in said specific pattern is equal to the sum of a distance from said reference plane to said surface to be measured and a distance between said reference planes set for said surfaces to be measured paired with each other; a simultaneous equation processing section for processing the derived simultaneous equations; and an output section to which a processing result of the simultaneous equation processing section is output, wherein said measuring section measures surface spacing between said surface to be measured for five pairs including: three pairs formed by combining two out of said three surfaces to be measured substantially in parallel to each other; one pair formed by rotating a surface to be measured of one of said three pairs by a predetermined number of degrees against the other surface; and another pair formed by displacing a surface to be measured of one of said three pairs in parallel to the other surface.