The polarization dependent diffraction efficiency and imaging properties of high numerical aperture (N.A.) holographic optical elements (HOEs) were investigated to determine the suitability of these elements for magneto-optic data storage head applications. Two-wave first-order coupled wave theory was combined with a local planar grating model to determine the s and p-polarization diffraction efficiency characteristics of these HOEs. Experimental results for 0.55 N.A. focusing HOEs fabricated in silver halide photographic emulsions and dichromated gelatin films demonstrated that the p-to-s-polarization diffraction efficiency ratio at the Bragg angle corresponded with theoretical results to within 5%. Diffraction based wave propagation theory and a geometrical ray trace model were used to evaluate the imaging performance of these elements. Results from the diffraction based wave propagation model showed that the HOEs imaging performance had very minimal polarization dependence. The ray trace model indicated precise alignment and good wavelength stability are needed to achieve diffraction limited performance.

Short, high intensity laser pulses induce nonlinear optical effects in the atmosphere that have the potential to make them propagate for long distances. Applications for long distance propagation of short pulses include active spectral remote sensing and laser lightning control. Much of the work in this field has been done with infrared pulses; however, it has been proposed that ultraviolet pulses have the advantage that longer pulse lengths can be used, thereby delivering more energy. Long pulse lengths lead to a simplified instantaneous model for the plasma response, which has been shown by Schwarz and Diels to admit steady state or oscillatory solutions corresponding to beam propagation. We have verified this model and have adjusted it to achieve closer agreement with numerical results. In this work we investigate the effects of transient behavior, and the stability of these solutions. Analysis of the modulational instability is done from the plane wave level to a full three dimensional model of the propagation. It is shown that both the transient behavior arising from the finite pulse length, and the modulational instability cause pulses to fragment over lengths on the scale of meters. We present results showing the growth of unstable modes in various propagation regimes. We discuss the pertinent length scales for ultraviolet pulses, as well as the impact of the instability and transient effects on theory and experiment. The results imply that continuous-wave models are very limited when used to predict dynamical properties of pulse propagation.

The aim of this dissertation has been to investigate the third order nonlinear susceptibility dispersion of molecules and polymers in order to estimate their purely electronic nonlinear response and in particular their optical Kerr nonlinear susceptibility in the 1 to 2 μm infrared spectral region. We have been successful in modeling with a four level system the near resonant cubic susceptibility of the polydiacetylene, poly(4-BCMU). In that case tunable Third-Harmonic-Generation and Two-Photon-Absorption measurements both agreed with the result of a Near-Infrared-Three-Wave-Mixing measurement. In the case of β-carotene and polythiophenes the four level model also fits the Third-Harmonic-Generation data well. In the previously mentioned cases the spectral behavior of the Two-Photon figure of merit derived by Mizrahi et al. is calculated. The four level model, when extrapolated far off resonance predicts that an all-optical switching device constructed with these materials will be dominated by Two-Photon-Absorption. A promising new class of side-chain substituted polymers with large microscopic second order nonlinearities was also investigated. Third-Harmonic-Generation measurements indicate that no forbidden two-photon transition is present in this case and that the magnitude of the nonlinear third order susceptibility is dominated by the charge-transfer nature of the nonlinear moieties combined with cascading of second order effects at a microscopic level. In the case of Sol-Gel thin films of varying TiO₂ concentration in SiO₂, the formula derived by Boling et al., based also on a three level model, predicts successfully the magnitude of the third order susceptibility. THG is in that case an invaluable technique used for the first time to measure relatively small nonlinear susceptibilities of glass-like thin films.

A Computed Tomographic Imaging Spectrometer (CTIS) is an imaging spectrometer which can acquire a hyper-spectral data set in a single snapshot (one focal plane array integration time) with no moving parts. A specially designed dispersing element, which separates light from the three-dimensional object cube into a grid of two-dimensional prismatic diffraction orders, is the key element in the instrument. The capabilities of the CTIS instrument can be improved by employing a more optimized grating design.There were two main goals to this research: (1) to design a novel CTIS disperser that will improve CTIS capabilities over the previous 5x5 disperser and (2) to integrate the new disperser into the CTIS and evaluate its performance compared to the 5x5 disperser. Six new disperser ideas were evaluated based on their performance in a number of computer simulations to determine the most optimal dispersion pattern. A new CTIS disperser incorporating a novel radial design pattern was developed and tested. Reconstruction results of various spatial and spectral targets are presented. Capabilities of the new CTIS instrument incorporating the radial grating are compared to the previous instrument employing a 5x5 disperser. While both dispersers perform similarly for point-source objects, the radial grating performs better than the previous disperser for extended sources.

Munition development has always been driven by the necessity of delivering enough explosives to a targeted object to destroy it. Targets that are protected by steel reinforced concrete housings have become increasingly more difficult to destroy. Improvements must be made in munitions engineering design to either deliver more payload to the target or to make the weapon more potent. In most cases, due to aircraft weight limitations, the delivery of more payload is not an option. Therefore, improving the destructive power of a weapon of a given payload requires the use of more powerful explosives. However, when the potency of an explosive is increased, its sensitivity to premature detonation also increases. The characteristics of the metal casing containing the explosive contribute significantly to the weapon's detonation sensitivity. Casing experience significant heating during weapon penetration. This heating can cause the weapon to detonate before it reaches its target location. In the past, computer codes used to model detonating weapons have not taken heating into account in their performance predictions. Consequently, the theoretical models and the actual field tests are not in agreement. New models, that include temperature information, are currently being developed which are based on work done in the area of computational fluid dynamics. In this research, a remotely located, high-speed, infrared (IR) camera is used to obtain detailed measurements of the passive radiation from an object in an energetic environment. This radiation information is used to determine both the emissivity and the temperature of the surface of an object. However, before the temperature or emissivity was determined, the functional form of the emissivity was calculated to be an Mth degree polynomial with respect to wavelength dependence. With the advent of large, high-speed, IR detector arrays, it has now become possible to realize IR imaging spectrometers that have very high spatial resolution. The IR spectrometer system developed in this research utilized a large detector array to allow multiple spectral images to be formed simultaneously on the image plane. In conjunction with the correct emissivity model, this imaging IR spectrometer can determine temperature to within ±5 degrees Celsius. These experimentally verified temperature maps were then integrated into the newly developed computer models. This additional information will result in more accurate computer codes for modeling the energetic environment. In turn, this will allow the weapon designer to accurately optimize weapon performance with respect to different materials, geometries and kinetics.

As a two-dimensional material, graphene has attracted great interest among the research groups and the industry due to its exceptional electrical, optical and mechanical properties. Currently, the primary methods for mass production of graphene are focused on the solution-processable chemical redox reaction. The oxidation of graphite introduces a large amount of oxygen functional groups attached onto its basal plane or edges, which makes graphene oxide (GO) sheets hydrophilic to form stable dispersions. However, the starting material graphite gradually becomes an insulator during the oxidation process as a part of planar sp2- hybridized geometry transformed to distorted sp3-hybridized geometry, which decreases the electrical conductivity. As a result, the reduction of GO is essential to recover graphene-like electrical conductivity for practical applications. In addition, the hydrophilic property of GO sheets allows coagulation of divalent metal ions in GO. These ions attach onto the GO basal plane and interact with functional groups resulting in GO/metal ion hybrid thin films with excellent electrical conductivity after reduction. In this work, the effect of coagulation of GO using copper ions (Cu2+) on optical and electrical properties of graphene oxide and reduced graphene oxide is studied. Two different reduction schemes were examined: direct, low-temperature annealing in vacuum and laser reduction of GO and GO-Copper films. This study includes the preparation of GO and GO-Cu stable dispersions, the fabrication of free standing thin films using a doctor blade process, the GO reduction, and the structural and electrical conductivity characterization of the resulting materials. Structural studies involved Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy/ Electron dispersive spectroscopy (SEM/EDS). A four-point probe measurement was used to examine film electrical resistivity.

The subject of this dissertation is the development of three-dimensional (3D) surface profilers for semiconductor back-end inspection. The value of this study is: 1) to provide a new phase-to-height relationship for Fourier Transform Profilometry (FTP) that is universal as it allows alternate FTP system architectures for a micrometer scale object measurement, and 2) to provide a new method for full field substrate warpage and ball grid array (BGA) coplanarity inspection using machine vision. The desire to increase electronic device performance has resulted in denser and smaller IC packaging. As the dimensions of the devices decrease, the requirements for substrate flatness and surface quality become critical in avoiding device failure. For a high yield production, there is an increasing demand in the requirement for the dimensional verification of height, which requires 3D inspection. Based on the current demands from the semiconductor industry, this dissertation addresses the development of fast in-line surface profilers for large volume IC package inspection. Specifically, this dissertation studies two noncontact surface profilers. The first profiler is based on FTP for measuring the IC package front surface, the silicon die and the epoxy underfill profile. The second profiler is based on stereovision and it is intended for inspecting the BGA coplanarity and the substrate warpage. A geometrical shape based matching algorithm is also developed for finding point correspondences between IC package images. The FTP profiler provides a 1 σRMS error of about 4 μm for an IC package sample in an area of 14 mm x 6.5 mm with a 0.13 second data acquisition time. For evaluating the performance of the stereovision system, the linearity between our system and a confocal microscope is studied by measuring a particular IC sample with an area of 38 mm x 28.5 mm. The correlation coefficient is 0.965 and the 2σdifference in the two methods is 26.9 μm for the warpage measurement. For BGA coplanarity inspection the correlation coefficient is 0.952 and the 2difference is 31.2 μm. Data acquisition takes about 0.2 seconds for full field measurements.

Notwithstanding several years of robust growth, solar energy still only accounts for<1% of total electrical generation in the US. Before solar energy can substantially replace fossil fuels subsidy-free at utility scale, further cost reductions and efficiency improvements are needed in complete generating systems. Flat panel silicon PV modules are by far the most dominant solar technology today, but have little room for improvement in efficiency and are limited by balance of system costs. Concentrated PV (CPV) is an alternate approach with long-term potential for much higher efficiency in sunny climates. In CPV modules, large area optics collect and concentrate direct sunlight onto small multi-junction cells with>40% conversion efficiency. Concentrated Solar Power (CSP) uses mirrors to concentrate sunlight onto thermally absorbing receivers, which generate electricity with convention thermal cycles. In this dissertation, four new optical approaches to CPV and CSP with potential for lower cost are analyzed. Common to each approach is the use of large square glass reflectors, which have very low areal cost (~$35/m^2) and field-proven reliability in the CSP industry. Chapter 2 describes a freeform toroidal lens array used to intercept the low concentration line focus of a parabolic trough to produce multiple high concentration foci (>800X) for multi-junction cells. In Chapter 3, three embodiments of dish mirrors and freeform lenslet arrays are explored, including an off-axis system. In each case, a dish mirror illuminates a freeform lenslet array, which divides sunlight equally to a sparse matrix of multi-junction cells. The off-axis optical system achieves +/-0.45° acceptance angle and averages 1215X geometric concentration over 400 multi-junction cells. Chapter 4 proposes a new architecture for CSP central receivers that achieves extremely high collection efficiency (>70%) with unconventional heliostat field tracking. In Chapter 5, the design and preliminary testing of a spectrum-splitting hybrid PV/thermal generator is discussed. This system has the advantage of 'drop-in' capability in existing CSP trough plants and allows for thermal storage, an important mitigation to the intermittency of the solar resource.