Optical phasing method based on scanning white-light interferometry for multi-aperture optical telescopes.

A novel, to the best of our knowledge, sensing approach based on scanning white-light interferometry (SWLI) is proposed to detect piston errors of the multi-aperture optical telescope. The scanning white-light interferometer is composed of a Mach-Zehnder interferometer (MZI) and an optical path modulator (OPM). A lenslet array is used to image the interferometric wavefront between the reference and the other individual apertures. The piston errors can be estimated from these SWLI signals focused by the lenslet array. The measurement range of the proposed method depends on the modulation range of the OPM and can reach millimeter order, and its accuracy is better than a 1/20 wavelength. In addition, the proposed method's amplitude-splitting interferometry of the MZI makes it fit for a multi-aperture optical telescope. We demonstrate a proof of concept and validate the feasibility of our proposed phasing method.