Optical incoherent synthetic aperture imaging by superposition of phase-shifted optical transfer functions
Mani Ratnam Rai, Joseph Rosen
Abstract
The concept of an optical incoherent synthetic aperture is widely used in astronomical interferometric telescopes. In this Letter, we propose a new, to the best of our knowledge, method to realize optical incoherent synthetic aperture imaging. The method is based on a superposition of optical transfer functions of incoherent imaging systems. Only two small sub-apertures, out of a much larger full synthetic aperture, are open at any given time, and they transfer light from the observed object to the image sensor. During the imaging process, the two sub-apertures move over the full synthetic aperture, where the gap between them starts from zero and grows with time. For every position of the pair of sub-apertures, two images are captured. In one of the images, the sub-apertures have the same phase value, and in the other image, one of the sub-apertures is phase shifted by <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>π</mml:mi> </mml:math> radian relative to the other one. The final image with the image resolution of the synthetic aperture is obtained as a superposition of the entire recorded images. Optical experiments are performed on reflective objects, and results of the synthetic aperture-based method demonstrate an imaging performance similar to that of direct imaging by a system with a single aperture of the size of the synthetic aperture.