Simple fringe illumination technique for optical superresolution

Abstract

The simple and precise fringe-illumination technique has been implemented to retrieve the missing information of a two-dimensional object. The object placed in a 4f optical system is illuminated with fringes, generated by a reflective-mode spatial light modulator. A set of three fringes, shifted in phase, sequentially illuminate the object, and correspondingly, three images are captured through CCD. The fringes illuminate the object and higher spatial frequencies primarily fall outside the aperture along horizontal direction heterodyne into the passband. To heterodyne higher spatial frequencies in a vertical direction, the fringes are swapped by 90 deg, and three further images are captured through CCD. These recorded images are processed to retrieve the object information using the spectrum-domain image-processing algorithm. The final image is higher in resolution compared to the band-limited image. For validity of technique, the theoretical concept was simulated and supported through experimental results. The presented system is stable against environmental factors due to on-axis geometry.