Thesis (M.S.)--Rochester Institute of Technology, 1990. / Includes bibliographical references (leaves 108-111).

Bidirectional reflectance is a fundamental property used for the analysis of radiative heat transfer. It is a form of reflectivity in which the spectral and directional dependencies of both the beam incident on a surface and the beam reflected from the surface are specified. A new system has been designed expressly for measuring bidirectional reflectance of engineering materials. This apparatus features a unique goniometer design in which the source is fixed, the sample is rotated to change the incident beam directions, and the sensor (which moves with the sample) is rotated about the sample to change the measured reflected beam direction. The system was used to measure the bidirectional reflectance of a surface consisting of flat-white paint on an aluminum substrate. The data for this quasi-diffuse surface were taken over a non-uniform grid. Algorithms are presented for interpolating and reporting values on a uniform grid which is appropriate for use in numerical radiative transfer codes. Bidirectional reflectance data can be used in the form of a look-up table although storage requirements will be large and resolution will be limited by grid resolution. Alternatively, the data can be modeled as continuous functions of the incident beam angle. A simple model of reflectance as the sum of a diffuse and a specular component is described. A second model with a diffuse component and a quasi-specular component is also presented which includes spread in both the polar and azimuthal directions. Both models are continuous and are based on curve fits to the data. / Graduation date: 1994

No description available.

Thesis (M.S.)--Rochester Institute of Technology, 1994. / Typescript. Includes bibliographical references (leaves 168-171).

Thesis (M.S.)--Mississippi State University. Department of Electrical and Computer Engineering. / Title from title screen. Includes bibliographical references.

No description available.

Metamorphic multiple quantum dots (QDs) on GaAs substrates were grown by molecular beam epitaxy (MBE). The metamorphic layers including In0.15Ga0.85As and AlAs were in-situ annealed at high temperature (T=800oC) to reduce the dislocations. InGaAs QDs were then grown on the metamorphic layers. We use the laser source and pulse voltage to modulate the dielectric constant of the samples in modulation reflectance measurement system. The inner electric field is obtained from the photo-reflectance Franz-Keldysh oscillation (FKO), and the energy transition is analyzed though the photoluminescence (PL), electroluminescence (EL), and photocurrent (PC) spectroscopy. The electroluminescence wavelength of InAs QDs on metamorphic In0.15Ga0.85As substrate can be push to ~1460 nm. The optimum emission quality is obtained by inserting 3-nm GaAs layer beneath the In0.15Ga0.85As buffer layer. The In0.15Ga0.85As buffer is flatter because of the GaAs layer, and the QDs become more uniform. We expect the InAs QDs on metamorphic GaAs substrate can be applied for optical communication in the £f=1550 nm region.

Non-melanoma skin cancer is the most prevalent malignancy in the world, with over a million annual positive diagnoses in the United States. If left untreated, these cancers cause morbidity and in rare cases, can become life threatening. The key to identifying and characterizing these tumors in the earliest stages, where they are most treatable lie in margin delineation in order to prevent recurrence. The visual obscurity of tumor morphology and physiology can make early detection a difficult task for dermatologists, particularly in the initial stages of cancer development. Tumor resection is a common course of action once they are discovered; however, there is a high recurrence rate due to incomplete removal of the malignant tissue. This dissertation presents an imaging system that can capture the spectral signatures correlating with morphological and physiological changes that accompany skin dysplasia. With this system, we may improve tumor margin delineation, reducing the number of incomplete tumor biopsies and false negative screenings. As an initial step of this process, we begin with a non-contact point sampling diffuse reflectance probe that mitigates the adverse effects of traditional contact probing. Validation of this probe is performed using tissue simulating phantoms spanning a biologically relevant range of optical and physiological properties to ensure that the non-contact format will not hinder performance relative to the contact probe. Cross polarization and auto-focus mechanisms were included in the design to reduce specular reflections and movement artifacts from in vivo measurements. This non-contact design was further developed into a platform for investigating the role of sampling geometry on diffuse reflectance measurements with the addition of a DMD spatial filter. Finally, we developed a hyperspectral DRSi system for the acquisition of wide-field maps of optical and physiological properties that is currently being tested on patients undergoing skin cancer screenings. The spectral output of this system has been validated for scattering and absorption across biologically relevant ranges using tissue simulating phantoms. The DRSi system was optimized for portability, ergonomics and resolution. / text

No description available.

Typescript. / Thesis (Ph. D.)--University of Hawaii, 1966. / Bibliography: leaves [92]-94. / ix, 94 l illus., tables