The recent discovery of photorefractive polymer composites with near 100% four-wave-mixing diffraction efficiency and high net optical gain by the author and coworkers at the University of Arizona has forwarded the advances of using organic materials to fabricate nonlinear optical devices. Nonlinear optical chromophores provide the optical properties for these new materials. Since there are thousands of molecules that are potential candidates to yield high performance nonlinear optical materials, a technique to quickly characterize the optical properties of these molecules is clearly needed. We have developed a frequency-dependent ellipsometric technique that simultaneously determines the first-order (anisotropic polarizability), second-order (first-hyperpolarizability), and third-order (second-hyperpolarizability) optical molecular coefficients of the chromophore. In this dissertation we will discuss the physics of these high performance nonlinear optical organic materials, and the characterization of their unique properties, leading to the development of our frequency-dependent ellipsometric technique. The technique itself will be discussed in detail, with an analysis of the molecules that are best suited for this type of measurement scheme, and a discussion of the limitations of this technique. Experimental data will be presented for a typical high performance nonlinear optical chromophore 4-(4'-nitrophenylazo)-1,3-di((3''- or 4''-vinyl)benzyloxy)benzene (NPADVBB).

A new phase-shifting scatterplate interferometer is realized by exploiting the polarization characteristics of a birefringent scatterplate. Controlling the component of polarization that is scattered allows the birefringent scatterplate to separate the test and reference beams. The advantages of this design are that it does not require auxiliary optics to be placed near the surface under test and the "hot spot" and background irradiance, which are inherent to scatterplate interferometers, can be eliminated. This study provides a description of the phase-shifting birefringent scatterplate interferometer, expands the theoretical model of the scatterplate interferometer to include polarization and phase shifting, analyzes the performance of the new interferometer and discusses possible sources of error induced by the design. In addition, a few component specific topics are addressed. Two methods for generating the birefringent scatterplate are presented and the role the scatterplate plays in removing the "hot spot" is explored. Furthermore, the practicality of using a liquid crystal retarder for phase shifting is analyzed in the process of determining the performance of the interferometer.

The condition in which the eye loses the ability to focus on near objects is called presbyopia. The use of Progressive Addition Lenses (PALs) is one alternative to treat this condition. PALs have a continuous change in power from the top of the lens to the bottom to avoid abrupt change in power. The increment of power in progressive addition lenses is accomplished by increasing the lens curvature from the upper part of the lens to the lower part of it. PALs consist of one freeform surface that provides this power change and the other surface is typically spherical (or aspheric) with its shape chosen to meet the wearer’s distance prescription. Because of its application, progressive lenses should be prescribed, made and tested in a very short period of time. A variety of testing methods have been developed through the years. However, these tests are designed to test symmetric optical elements, or use additional optics that are very expensive. What is needed is a new technique that can overcome these difficulties in an economic and fast way. In this dissertation, several methods were implemented to test the freeform surface shape of a Progressive Addition Lens. Two different types of methods were used: contact methods such as the use of a linear profilometer, and a Coordinate Measurement Technique (CMM); non-contact methods such as the SCOTS Test by refraction, and ultraviolet (UV) deflectometry. Besides surface shape, acceptance of progressive addition lenses must be studied. A methodology to characterize the visual performance of Progressive Addition Lenses is presented with scene simulation of how the wearer sees through the spectacle. Simulated images are obtained by calculating the point spread function through a lens-eye model in function of gaze angle. A modified superposition technique which interpolates the psfs for different gaze angles, as well as at different object distances is developed and used to create simulated images. Such scene simulations would allow patients to examine the variety of tradeoffs with the various treatment modalities and make a suitable choice for treatment.

Gamma-ray detectors based on high-density semiconductors, such as cadmium zinc telluride, are being developed for applications in nuclear medicine, astronomy and the monitoring of nuclear weapons material. In contrast to the more commonly used scintillators, which convert gamma-ray energy into light, semiconductors directly convert the energy of a gamma ray into electrical current. This direct conversion often leads to the perception that gamma-ray detection in semiconductors is not an estimation problem. This dissertation presents the contrasting view that gamma-ray detection in semiconductors is fundamentally an estimation problem, and it is only through the appropriate analysis of gamma-ray signals that optimal energy resolution and spatial resolution can be achieved. To estimate interaction parameters, such as the energy of the gamma ray and its interaction position, it is first necessary to have an accurate model of the detector system. In this work, the system consists of slabs of CdZnTe with arrays of pixel electrodes mounted on integrated readout circuits. A theoretical model of detector behavior is presented, including a new model for charge spreading in the detector. Methods for experimentally determining detector behavior are developed based on mapping detectors with narrow beams of gamma rays. Estimating the interaction positions and energies proceeds from a statistical model of the production of pixel signals, derived from our physical model. Energies and interaction positions are estimated by maximizing the likelihood function. The likelihood is the probability that a gamma ray with a given position and energy will produce an observed set of pixel signals. This maximum-likelihood estimation improves the energy resolution over simpler methods and can give the interaction position in three dimensions. A likelihood function can be calculated for an entire set of gamma rays, in which case an image can be estimated from the raw data without ever estimating individual interaction positions and energies. The Expectation-Maximization algorithm is used to reconstruct images and energy spectra by maximizing the ensemble likelihood function. In this work, the list-mode form of the algorithm is used, meaning that the raw data consist of lists of pixel signals for each gamma ray. Both spatial and energy resolution improve when this algorithm is applied to the raw pixel signals.

The Remote Sensing Group (RSG) at the College of Optical Sciences of the University of Arizona implements a reflectance-based approach for vicariously calibrating remote sensors. This includes the automated radiometric data collection of the surface of Railroad Valley, Nevada (RRV) using four stationary Ground-Viewing Radiometers (GVRs). There are features such as cracks, pits, and small mounds on the surface of RRV. The ground instantaneous field-of-view (GIFOV) of a stationary GVR may contain more or less of these features than is indicative of the entire site. This thesis presents a design to increasing the spatial sampling via an automated motion control system that will translate the GVR over RRV a short distance. This will make for more accurate data collection in the automated reflectance-based calibration approach.

Nonlinear optical transverse effects, which arise from the interaction of a Gaussian beam with a nonlinear medium, are discussed. They are cw on-resonance enhancement (CORE), cw off-resonance rings, crosstalk, intracavity phase switching, self-defocusing of a bistable etalon, and thin-sample-encoding (TSE) self-lensing (i.e., self-focusing or self-defocusing) bistability and instabilities. CORE is the enhancement of the on-axis intensity of an on-resonance laser beam in a two-level medium. We report the first observation of CORE using sodium vapor. Cw off-resonance rings, resulting from a pure phase encoding or from simultaneous phase and amplitude encodings, are observed using sodium vapor. These rings have been observed many time before, but we have made the first careful comparison with numerical calculations. Parallel operation and external switching are two crucial themes for the application of bistable optical devices (BODs). For parallel operation, crosstalk between nearby BODs on the same etalon due to diffraction coupling may need to be avoided. Minimum separations needed to ensure independent operation are computed. For external switching, intracavity phase switching using a plane-wave input can switch on (or off) a BOD using an external pulse. The validity of this concept for a Gaussian input is numerically simulated. Self-defocusing effects, resulting in some interesting effects in the transverse bistable loops, are observed using a GaAs-GaAlAs bistable etalon. The results are confirmed by numerical simulations. TSE self-lensing bistability is observed using a short sodium cell and a single mirror. TSE self-lensing bistability results from an enhancement in the feedback via self-lensing of the beam. The lack of an optical resonator and the use of a thin medium make TSE setup a good candidate to study the Ikeda instability. We report the first observation of the Ikeda instability in this all-optical passive system using a cw input. Numerical simulations show a rich bifurcation sequence not yet fully studied experimentally.

PEPPER is a high-speed differential Polarization-Encoded Photometer and Polarimeter developed in the Center for Astronomical Adaptive Optics at the University of Arizona, Tucson, by Dr. Dan Potter and Matthew Graham. PEPPER is capable of acting as a high-speed polarimeter by using electro-optical switching to chop between standard star and target star, and between in and out-feature bandpass fi lter at frequencies fast enough to suppress atmospheric variations (1). PEPPER is capable of either high-speed polarimetry or di fferential photometry using a combination of simultaneous imaging and electro-optical switching. In the di fferential photometry mode, PEPPER utilizes the electro-optical switching to calibrate instrumental and atmospheric photometric variation. This technique coupled with a zero-read noise photon counting detector achieves photon noise limited results demonstrated to an accuracy of less than 1 part in 10⁵. I will present the design concept behind the photometer and the polarimeter mode of PEPPER, as well as, results from observations in the di fferential photometer mode at the Steward 90 inch telescope, at the Kitt Peak National Observatory, Tucson, Arizona. Results from the analysis of near IR polarimetry observations of young stars with circumstellar disks taken at the Gemini North Telescope with the Hokupa'a adaptive optics system are also presented.

With the future need of larger telescopes, membrane mirrors are an option to create large-scale reflectors needed for space base observation at a lower cost than conventionally made mirrors. Proposed methods of how membrane mirrors have been put into place with ideas such as Dr. Chris Walker’s inflatable spherical telescope and the L’Garde Inflatable Antenna Experiment (IAE). With data from L’Garde, Dr. Aden Meinel presented the curvature of a membrane mirror does not produce a spherical curvature. From there a look into what sort of aberrations that curvature produces and attempts to correcting it or processing it to other benefits by altering the material. Procedures will be done on a small-scale in a process that can be applied to larger-scale systems.

We have developed a simulation of the AdaptiSPECT small-animal Single Photon Emission Computed Tomography (SPECT) imaging system. The simulation system is entitled SimAdaptiSPECT and is written in C, NVIDIA CUDA, and Matlab. Using this simulation, we have accomplished an analysis of the Scanning Linear Estimation (SLE) technique for estimating tumor parameters, and calculated sensitivity information for AdaptiSPECT configurations.SimAdaptiSPECT takes, as input, simulated mouse phantoms (generated by MOBY) contained in binary files and AdaptiSPECT configuration geometry contained in ASCII text files. SimAdaptiSPECT utilizes GPU parallel processing to simulate AdaptiSPECT images. SimAdaptiSPECT also utilizes GPU parallel processing to perform 3-D image reconstruction from 2-D AdaptiSPECT camera images (real or simulated), using a novel variant of the Ordered Subsets Expectation Maximization (OSEM) algorithm. Methods for generating the inputs, such as a population of randomly varying numerical mouse phantoms with randomly varying hepatic lesions, are also discussed.

High-power laser systems, such as the National Ignition Facility (NIF) project at Lawrence Livermore National Laboratories (LLNL), require optics of extremely high quality. Surface errors, especially periodic surface relief structures, can lead to focal spot degradation at best and serious damage to downstream optics at worst. The optics in these systems must be characterized with a high degree of accuracy to ensure proper operation. To provide system optics of sufficient quality, the testing apparatus must measure surface structure with high fidelity and cannot introduce significant errors into the measurements. This paper deals with measurements taken on two WYKO phase-shifting laser Fizeau interferometers to optimize their ability to meet the measurement requirements for optics in high-power laser systems. Increasingly, tolerances on optics are being specified with the power spectral density function (PSD) of the surface height data, and thus the power spectrum is used to characterize the measurement system. The system transfer function, which is the ratio of the measured amplitude of frequency components to the actual, is calculated using several methods. The effects of various parameters on the calculated system transfer function are studied. First, the use of the finite Fourier transform to estimate the power spectrum from surface profile data was studied. Next, simulated measurements were analyzed to determine the effects of rotation, feature location, noise, windowing, and other variables on the calculated power spectral density. After the theoretical analysis, the interferometer transfer function was calculated using two techniques. The effects of wavefront propagation on the measurements were also studied. Measurements were first taken on a 150mm laser Fizeau system where the effect of changing various parameters was studied. Final measurements were taken on the 600mm system to verify system performance. The large aperture laser Fizeau interferometer as built had a system transfer that surpassed the system requirements with regards to transfer function and measurement noise. The system measured frequency amplitudes with 70% fidelity up to half the Nyquist frequency. In addition, the power spectrum of the noise plots was below the system specification of 0.1ν⁻¹·⁵⁵nm²mm over the spatial frequencies ν of interest,¹ more than ten times lower than the specification on the parts to be measured.