Experimental comparison of a Shack-Hartmann sensor and a phase-shifting interferometer for large-optics metrology applications.
We performed a direct side-by-side comparison of a Shack-Hartmann wave-front sensor and a phase-shifting interferometer for the purpose of characterizing large optics. An expansion telescope of our own design allowed us to measure the surface figure of a 400-mm-square mirror with both instruments simultaneously. The Shack-Hartmann sensor produced data that closely matched the interferometer data over spatial scales appropriate for the lenslet spacing, and much of the <20-nm rms systematic difference between the two measurements was due to diffraction artifacts that were present in the interferometer data but not in the Shack-Hartmann sensor data. The results suggest that Shack-Hartmann sensors could replace phase-shifting interferometers for many applications, with particular advantages for large-optic metrology.
Koch
J A
JA
Lawrence Livermore National Laboratory, University of California, P.O. Box 808, L-481, Livermore, California 94551, USA. koch1@llnl.gov
Presta
R W
RW
Sacks
R A
RA
Zacharias
R A
RA
Bliss
E S
ES
Dailey
M J
MJ
Feldman
M
M
Grey
A A
AA
Holdener
F R
FR
Salmon
J T
JT
Seppala
L G
LG
Toeppen
J S
JS
Van Atta
L
L
Van Wonterghem
B M
BM
Whistler
W T
WT
Winters
S E
SE
Woods
B W
BW