No abstract

A high-resolution image of an object is reconstructed by superposition of all the interference patterns accumulated from certain locations of two small sub-apertures moving on the perimeter of a synthetic aperture.

The optical incoherent synthetic aperture (SA) has wide applications in astronomy and biomedical optics. Super-resolution imaging can be achieved through SAs with an effective size several times larger than the size of the physical apertures. In this Letter, we propose a new, to the best of our knowledge, method to realize optical incoherent SA imaging. Instead of scanning the entire area of the full SA, we show that similar imaging performance can be achieved by scanning only along its perimeter. At any given time, only a single pair of sub-apertures located at the SA perimeter is open and reflects the incident light toward an image sensor. For each location of the two sub-apertures, two interfering images are captured. The phase difference between the two sub-apertures is zero for one interfering image and π for the other. The image of the object is reconstructed by superposition of all the interfering images from some of the sub-aperture locations and with the two-phase differences, 0 and π, between the two sub-apertures. Optical experiments have been performed using reflective objects, and the results demonstrate similar imaging capabilities as that of direct imaging with the aperture size of the SA. Furthermore, we have compared the proposed SA imaging results with the results of annular and full aperture direct imaging.

In this paper, we propose a method for the generation of a two-dimensional spin-orbit beam lattice using a Dammann grating. A Dammann grating is fabricated and is illuminated by ellipse field/vector filed singular beam that contains a polarization singularity. Since, Dammann grating is used to produce equal-intensity light spots, each of the spin-orbit beams in the lattice has equal intensity distribution. Interestingly, they also have the same polarization distribution as that of the input light. Unlike the interferometric methods of lattice generation, the diffractive method proposed here produces lattices of the same index singularities. Simulation and experimental results are provided to demonstrate the concept.