Absolute profile measurement of large moderately flat optical surfaces with high dynamic range.
We present a novel procedure for absolute, highly-accurate profile measurement with high dynamic range for large, moderately flat optical surfaces. The profile is reconstructed from many sub-profiles measured by a small interferometer which is scanned along the specimen under test. Additional angular and lateral distance measurements are used to account for the tilt of the interferometer and its precise lateral location during the measurements. Accurate positioning of the interferometer is not required. The algorithm proposed for the analysis of the data allows systematic errors of the interferometer and height offsets of the scanning stage to be eliminated and it does not reduce the resolution. By utilizing a realistic simulation scenario we show that accuracies in the nanometer range can be reached.
Wiegmann
A
A
Physikalisch-Technische Bundesanstalt Braunschweig Bundesallee 100, 38116 Braunschweig, Germany. axel.wiegmann@ptb.de
Schulz
M
M
Elster
C
C
D000465:Algorithms; D019544:Equipment Failure Analysis / Q000379:methods*; D007368:Interferometry / Q000379:methods*; D055095:Optics and Photonics / Q000295:instrumentation*; D012031:Refractometry / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013499:Surface Properties