Sparse aperture phasing with phase diversity: Experimental Results

Abstract

Phasing the sub apertures of a multiple aperture telescope is a difficult problem that has been addressed in various ways. Hartmann sensors and knife edge tests are techniques that work well for point source objects such as stars. Null fringe tracking is also suitable for point sources. However, none of these techniques are adequate for extended object imaging. Radial shearing white-light interferometers have been proposed and tested but are complicated to implement and have a strong object dependence. Laser metrology systems are extremely accurate but do not give a direct measurement of the phase errors and can be difficult to implement. Phase diversity is a very simple phasing technique that is suitable for extended objects and has developed into a mature technology over the past five years.