NPS sparse aperture testbed

This paper presents NPS Sparse Aperture Testbed development to demonstrate sparse aperture concept. The testbed has a sparse aperture array consisting of three 2-inch diameter F/20 spherical mirrors. Each mirror is connected to a separate 6 axis ThorLabs stage to simulate motion in satellite formation. The beam combining platform employs three 1-inch diameter flat mirrors mounted on the correcting PI tip/tilt/piston actuated stages to provide coherent beam combining capabilities. For metrology, the system uses Zygo 9 single-axis displacement measuring interferometers. Transformation matrix between the aperture motion measured by the metrology and required motion by the correcting piston and tip/tilt stages was determined. The mirrors were moved continuously representing satellite formation errors and the motion was measured by laser metrology and using transformation matrix, the correcting stages were commanded, resulting in coherent combination of images from three apertures.