Experimental demonstrations of optical synthetic aperture imaging using spatial heterodyne interferometry have been
achieved at the Lockheed Martin Advanced Technology Center in Palo Alto, CA. In laboratory experiments, a reflective
binary star scene and an Air Force resolution bar target were illuminated and imaged by a 532 nm laser and an afocal
telescope. The real aperture diffraction limit in the horizontal direction was 65 microRadians. Complex pupil
information was obtained by mixing the scattered return light from the target with light from an off-axis local oscillator,
thus forming a linear fringe pattern on a CCD array placed at the pupil plane. Fourier transform methods were used to
extract pupil amplitude and phase. By translating the real aperture pupil, collecting data at different locations, and
extracting and combining the pupil data, a synthetic aperture twice the real aperture size was created. In the
reconstructed image resulting from the synthetic aperture pupil data, features down to 32 microRadians were clearly
High spectral resolution Fourier transform imaging spectroscopy has been demonstrated at the Lockheed Martin
Advanced Technology Center. A testbed was built using a Michelson interferometer with a two-stage end-mirror control
system. Homodyne laser metrology was used to sense relative tip, tilt and piston in the interferometer, and a 3-degree of
freedom fast steering mirror in conjunction with a linear actuator stage provided sub-nanometer actuation control over
20 millimeters of piston range. The range of piston over which signal was present allowed for spectral resolution at the
nanometer level in the visible / near infrared (VNIR) band for every pixel in the reconstructed image.
A high bandwidth, gimbaled, fast steering mirror (FSM) assembly has been designed and tested at the Lockheed Martin Space Systems Company (LMSSC) Advanced Technology Center (ATC). The design requirements were to gimbal a 5 cm diameter mirror about its reflective surface, and provide 1 KHz tip/tilt/piston control while maintaining λ/900 flatness of the mirror. The simple, yet very compact and rugged device also has manual tip/tilt/piston alignment capability. The off-the-shelf Piezo translators (PZT) actuators enable reliable and repeatable closed loop control. The adopted solution achieves a good mass balance and gimbaled motion about the center of the mirror front surface. Special care was taken to insure the best positioning means with the mounted mirror assembly held kinematically in place. The manual adjusters have very good resolution, with the capability to be locked in place. All solutions were thoroughly modeled and analyzed. This paper covers the design, analysis, fabrication, assembly, and testing of this device. The FSM was designed for ground test only.