Optical scanning holography, which was proposed by Poon[1], is a fascinating technology to record holographic information. The technique is applied in the operation of scanning holographic microscopy to record the entire three-dimensional volume of a biological specimen in the form of a hologram. With the data captured, a digital reconstruction or decoding is used to reconstruct the hologram of that such specimen. An accurate reconstruction of the recorded data provides with an in-depth analysis in the area where random noise and other imperfection effects may occur. In this thesis, three different approaches of reconstruction process are presented to provide in high-resolution a comparison between theoretical and experimental reconstruction a hologram of fluorescent beads. The first approach is to use only the experimental pinhole hologram recorded to correlate with the hologram of the object to give the reconstruction of the section. The second approach is to use the propagated pinhole hologram to reconstruct at an arbitrary depth. Finally, the third approach is to reconstruct without using the experimental pinhole hologram but with diffraction theory. Comparing these results in high-resolution gives us analysis of the reconstruction noise due to optical aberration. / Master of Science

High-pass filtering has been shown to be a promising method for edge detection in optical scanning holography. By using a circular function as a pupil for the system, the radius of the circle can be varied to block out different ranges of frequencies. Implementing this system in simulation yields an interesting result, however. As the radius increases, a singular edge can split off into two edges instead. To understand the specific conditions under which this split occurs, Airy pattern filtering and single-sided filtering were implemented to analyze the results from the original high-pass simulation. These methods were tested with different input objects to assess any common patterns. Ultimately, no definitive answer was found, as Airy pattern filtering resulted in inconsistent results across different input objects, and single-sided filtering does not completely isolate the edge. Nonetheless, the documented results may aid a future understanding of this phenomenon. / Master of Science / Holograms are three-dimensional recordings of an object, reminiscent of how a photograph records a two-dimensional image of an object. Detecting edges in images and the reconstructed images from holograms can help us identify objects within the recorded image or hologram. In computer vision, common edge detection techniques involve analyzing the image's spatial frequency, or changes in relative intensity over space. One such technique is high-pass filtering, in which lower spatial frequencies are blocked out. High-pass filtering can also be applied to holographic imaging systems. However, when applying high-pass filtering to a holographic system, detected edges can split into two as higher frequencies are filtered out. This thesis examines the conditions for why this split-edge phenomenon occurs by modifying the original recorded object and the filtering mechanism, then analyzing the resultant holograms. While the results did not give a conclusive answer, they have been documented for the purpose of further research.

Throughout the decades, different techniques have been proposed to improve the depth-of-focus in optical microscopy. Common techniques like optical sectioning microscopy and scanning confocal microscopy have innate problems. By simply modifying the pupil function in microscope imaging system, we can also extend the depth-of-focus. The scanning system with a thin annular pupil has a high depth-of-focus and can scan the whole object, but the output light is too dim to be detected well by a photodetector. In this thesis, we propose a scanning technique employing an optical heterodyne scanning system using a difference-of-Gaussians (DoG) pupil. The object is illuminated by the combined beam which consists of two Gaussian beams with different waists, frequencies, and amplitudes. This system does not block most light like the annular pupil system and can obtain high depth-of-focus. The main objective of the thesis is to extend the depth-of-focus using the proposed system. The depth-of-focus characteristics of the DoG pupil function are examined and compared with those of well-known functions such as the circular, annular, and Gaussian pupils. / Master of Science

Optical scanning holography (OSH) [1] has the benefit of recording the entire three-dimensional (3-D) volume of a specimen in the form of a two-dimensional (2-D) hologram. Reconstruction of the original volume can be accomplished by applying digital reconstruction or decoding techniques to the recorded hologram. Accurate reconstruction of the 3-D volume and more specifically, the individual 2-D optical sections without artifacts such as out-of-focus haze from adjacent sections has been the focus of much work including algorithms, optical techniques, and combinations of the two. This dissertation presents several different techniques for enhancing the reconstruction of a recorded specimen and its optical sections including the use of optical coding and phase filtering techniques in the traditional OSH optical system. / Ph. D.

We present a three-dimensional (3-D) optical image matching technique and location extraction techniques of matched 3-D objects for optical pattern recognition. We first describe the 3-D matching technique based on two-pupil optical heterodyne scanning. A hologram of the 3-D reference object is first created and then represented as one pupil function with the other pupil function being a delta function. The superposition of each beam modulated by the two pupils generates a scanning beam pattern. This beam pattern scans the 3-D target object to be recognized. The output of the scanning system gives out the 2-D correlation of the hologram of the reference object and that of the target object. When the 3-D image of the target object is matched with that of the reference object, the output of the system generates a strong correlation peak. This theory of 3-D holographic matching is analyzed in terms of two-pupil optical scanning. Computer simulation and optical experiment results are presented to reinforce the developed theory. The second part of the research concerns the extraction of the location of a 3-D image matched object. The proposed system basically performs a correlation of the hologram of a 3-D reference object and that of a 3-D target object, and hence 3-D matching is possible. However, the system does not give out the depth location of matched 3-D target objects directly because the correlation of holograms is a 2-D correlation and hence not 3-D shift invariant. We propose two methods to extract the location of matched 3-D objects directly from the correlation output of the system. One method is to use the optical system that focuses the output correlation pattern along depth and arrives at the 3-D location at the focused location. However, this technique has a drawback in that only the location of 3-D targets that are farther away from the 3-D reference object can be extracted. Thus, in this research, we propose another method in which the extraction of a location for a matched 3-D object is possible without the aforementioned drawback. This method applies the Wigner distribution to the power fringe-adjusted filtered correlation output to extract the 3-D location of a matched object. We analyze the proposed method and present computer simulation and optical experiment results. / Ph. D.

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. / Ph. D.