TY - JOUR
T1 - An automated subaperture stitching interferometer workstation for spherical and aspherical surfaces
AU - Fleig, Jon
AU - Dumas, Paul
AU - Murphy, Paul E.
AU - Forbes, Greg W.
PY - 2003
Y1 - 2003
N2 - Subaperture stitching is a well-known technique for extending the effective aperture and dynamic range of phase measuring interferometers. Several commercially available instruments can automatically stitch flat surfaces, but practical solutions for stitching spherical and aspherical surfaces are inherently more complex. We have developed an interferometer workstation that can perform high-accuracy automated subaperture stitching of spheres, flats, and mild aspheres up to 200 mm in diameter. The workstation combines a six-axis precision stage system, a commercial Fizeau interferometer of 4″ or 6″ aperture, and a specially developed software package that automates measurement design, subaperture data acquisition, and the mathematical reconstruction of a full-aperture phase map. The stitching algorithm incorporates a general constrained optimization framework for compensating for several types of errors introduced by the interferometer optics and stage mechanics. These include positioning errors, viewing system distortion, and the system reference wave. We present repeatability data, and compare stitched full-aperture measurements made with two different transmission spheres to a calibrated full-aperture measurement. We also demonstrate stitching's ability to test larger aspheric departures on a 10 μm departure parabola, and compare the preliminary results with a full-aperture null test.
AB - Subaperture stitching is a well-known technique for extending the effective aperture and dynamic range of phase measuring interferometers. Several commercially available instruments can automatically stitch flat surfaces, but practical solutions for stitching spherical and aspherical surfaces are inherently more complex. We have developed an interferometer workstation that can perform high-accuracy automated subaperture stitching of spheres, flats, and mild aspheres up to 200 mm in diameter. The workstation combines a six-axis precision stage system, a commercial Fizeau interferometer of 4″ or 6″ aperture, and a specially developed software package that automates measurement design, subaperture data acquisition, and the mathematical reconstruction of a full-aperture phase map. The stitching algorithm incorporates a general constrained optimization framework for compensating for several types of errors introduced by the interferometer optics and stage mechanics. These include positioning errors, viewing system distortion, and the system reference wave. We present repeatability data, and compare stitched full-aperture measurements made with two different transmission spheres to a calibrated full-aperture measurement. We also demonstrate stitching's ability to test larger aspheric departures on a 10 μm departure parabola, and compare the preliminary results with a full-aperture null test.
KW - Absolute calibration
KW - Error compensation
KW - Interferometry
KW - Subaperture stitching
UR - http://www.scopus.com/inward/record.url?scp=2342572336&partnerID=8YFLogxK
U2 - 10.1117/12.506254
DO - 10.1117/12.506254
M3 - Article
AN - SCOPUS:2342572336
VL - 5188
SP - 296
EP - 307
JO - Proceedings of SPIE - The International Society for Optical Engineering
JF - Proceedings of SPIE - The International Society for Optical Engineering
SN - 0277-786X
ER -