Resolution enhancement in nonlinear interferenceless COACH with point response of subdiffraction limit patterns.

Abstract

Interferenceless coded aperture correlation holography (I-COACH) is a non-scanning, motionless, incoherent digital holography technique for 3D imaging. The lateral and axial resolutions of I-COACH are equivalent to those of conventional direct imaging with the same numerical aperture. The main component of I-COACH is a coded phase mask (CPM) used as the system aperture. In this study, the CPM has been engineered using a modified Gerchberg-Saxton algorithm to generate a random distribution of subdiffraction spot arrays on the digital camera as a system response to a point source illumination. A library of point object holograms is created to calibrate the system for imaging different lateral sections of a 3D object. An object is placed within the calibrated 3D space and an object hologram is recorded with the same CPM. The various planes of the object are reconstructed by a non-linear cross-correlation between the object hologram and the point object hologram library. A lateral resolution enhancement of about 25% was noted in the case of I-COACH compared to direct imaging.