Twin-image problems in optical scanning holography

Abstract

Real-time optical scanning holography, which was first suggested by Poon and Korpel, was originally analyzed by Poon using an optical transfer function approach. The recording of holographic information using the optical heterodyne scanning technique has several advantages over conventional nonscanning optical holographic recording methods. We first review a new 3-D imaging technique called optical scanning holography (OSH) by acousto-optic two-pupil synthesis. We then derive 3-D holographic magnification, using three points configured as a 3-D object. We demonstrate three-dimensional imaging capability of OSH by holographically recording two planar objects at different depths and reconstructing the hologram digitally and optically using an electron-beam-addressed spatial light modulator (EBSLM). The second part of this dissertation investigates twin-image noise in optical scanning holography. In optical scanning holography, holographic information of an object is generated by 2-D active optical scanning. The optical scanning beam can be a time-dependent Gaussian apodized Fresnel zone pattern. We derive the resolution achievable with such a scanning beam. We then discuss the use of a larger and a smaller Fresnel zone pattern for holographic recording to investigate twin-image noise which results in the unwanted image in the reconstructed field. Finally, we discuss a novel multiplexing technique to solve the twin image problem in optical scanning holography without the use of a spatial carrier as commonly used in conventional off-axis holography. The technique involves simultaneously acquiring a sine and cosine Fresnel zone-lens pattern coded images by optical scanning. A complex addition of the two coded images then will be performed and decoded to give a twin-image rejection reconstruction.