Patent Document ID: 20060098209
Application ID: 11265853
Patent Flag: 0

Claim One:
1. A high-speed interferometer for measuring surface profiles, said high-speed interferometer comprising: a reference leg including a reference object and a measurement leg in which the test surface is located; a source for illuminating the test surface and the reference object with a wavefront that nominally is of the same shape as that of the test surface to produce interference patterns containing information about the instantaneous wavefront difference between the reference object and test surface; a part stage for selectively moving the test surface relative to the reference object to align the test surface and reference object by setting the tilt and tip between them to be nominally zero, deliberately change the relative tilt between the reference object and test surface by predetermined incremental amounts to generate a series of calibration interferograms containing information about the wavefront differences between the reference object and test surfaces including the influence of the incremental tilts, and to selectively orient the test surface and reference object to make measurments; a two-dimensional detector having a plurality of pixels each corresponding to a respective location on the test surface; optics for forming an image of said interference patterns on said two-dimensional detector during one frame thereof; and a processor for analyzing said calibration interferograms, generating error maps corresponding to said incremental tilts, generating correction functions based on said error maps for each incremental tilt angle, and applying those correction functions to a measurement of the test surface taken at a predetermined measurement tilt angle.