Enhanced resolution and throughput of Fresnel incoherent correlation holography (FINCH) using dual diffractive lenses on a spatial light modulator (SLM)

Barak Katz,Joseph Rosen,Roy Kelner,Gary Brooker

doi:10.1364/oe.20.009109

Abstract

Fresnel incoherent correlation holography (FINCH) records holograms under incoherent illumination. FINCH was implemented with two focal length diffractive lenses on a spatial light modulator (SLM). Improved image resolution over previous single lens systems and at wider bandwidths was observed. For a given image magnification and light source bandwidth, FINCH with two lenses of close focal lengths yields a better hologram in comparison to a single diffractive lens FINCH. Three techniques of lens multiplexing on the SLM were tested and the best method was randomly and uniformly distributing the two lenses. The improved quality of the hologram results from a reduced optical path difference of the interfering beams and increased efficiency.

Highlights

The developments of spatial light modulators (SLMs) during the last three decades have boosted the technology of computerized holography
An SLM can even be used as a means to synthesize computer generated holograms (CGHs) by iterative algorithms [4], or it can be used as a spatial phase modulator for a phase shifting process in a digital holography recorder [5]
We extend this topic of dual lens Fresnel incoherent correlation holography (FINCH), and analytically show that for a given source bandwidth, and image magnification, this design can be superior over the single diffractive lens configuration

Summary

Introduction

The developments of spatial light modulators (SLMs) during the last three decades have boosted the technology of computerized holography. In the Fresnel incoherent correlation holography (FINCH) [6,7,8,9,10,11,12,13] system, which is the main topic of this study, the SLM plays three important roles It splits the light coming from each object point into two separated wavefronts. The principle of operation is as follows; incoherent light emitted from each point in the object being imaged is split by two diffractive lenses displayed on the SLM into two beams that interfere with each other. The camera records the entire interference patterns of all the beam pairs emitted from the entire object points, creating a hologram Three such holograms, each with a different phase constant in the pattern of one of the diffractive lenses, are recoded sequentially and are superimposed in order to eliminate the unnecessary bias term and the twin image from the reconstructed scene. In the experimental section of this study we compare three different methods

Dual lens FINCH analysis

Experimental methods and results

Discussion and conclusions