Computer-Aided Alignment Of A Wide-Field, Three-Mirror, Unobscured, High-Resolution Sensor

Santa Barbara Research Center has been exploring the technology related to the design, tolerance, and alignment of wide-field, all-reflecting sensors for multispectral earth observation. The goals of this study are to design an optical system with reduced fabrication risks, to develop a detailed tolerance budget, and to demonstrate our ability to align the system to a tolerance of 0.05 waves rms, at 0.6328 microns. The optical system is a three-mirror, unobscured telescope. It is telecentric and flat field over 15 degrees at F/4.5, and achieves diffraction-limited imagery at visible wavelengths. A separate paper 1 describes the design and error budget approach for the telescope. This paper reports on the effort that led to the alignment of a scaled, prototype optical system. The approach used interferometric measurements of the wavefront at multiple field points and a computer alignment algorithm to define the rigid-body adjustments of the mirrors to achieve the alignment goal.