Browsing by Subject "Reflectance spectroscopy"
Now showing 1 - 4 of 4
Results Per Page
Sort Options
Item Autofluorescence and diffuse reflectance patterns in cervical spectroscopy(2005) Marín, Nena Maribel; Richards-Kortum, Rebecca, 1964-Item Depth-resolved measurements in multi-layer scattering media using linearly and elliptically polarized reflectance spectroscopy(2016-08) Bailey, Maria Jimenez; Sokolov, Konstantin V. (Associate professor); Dunn, Andrew; MacAulay, Calum; Markey, Mia; Rylander, H. GradyOptical reflectance spectroscopy is a non-invasive tool that can provide quantitative information on tissue morphology and biochemistry. However, interpreting the depth-dependent signals from multi-layer tissue can be challenging as optical signatures are from a range of depths. The focus of this dissertation is on the development of light-based systems for the depth-resolved characterization of multi-layered tissue. Specifically, this dissertation concentrates on the assessment of polarized reflectance spectroscopy (PRS) with linearly and elliptically polarized light. PRS is a form of elastic scattering spectroscopy that relies on polarization gating to selectively isolate polarization maintaining photons in order to probe superficial depths. Polarization gating relies on the observation that as light travels deeper into a turbid medium and undergoes scattering, the incident polarization will become depolarized. Polarization-sensitive techniques for imaging and spectroscopy have received attention for their relatively simple and low-cost instrumentation to favorably collect either superficial or deep penetration photons. In this dissertation, I will present a fiber optic probe that combines polarization gating with linearly polarized light and an oblique detection geometry via multiple beveled collection fibers to detect scattering within various depths in tissue. The performance of the oblique polarized reflectance spectroscopy (OPRS) probe was evaluated in a clinical trial of oral cavity cancer. I will also discuss in this dissertation a new system based on elliptical polarization. The probing depth of elliptical polarized reflectance spectroscopy (EPRS) was assessed in turbid media by tuning the ellipticity of polarized light.Item Photomodulated reflectance spectroscopy on gallium arsenide and gallium indium arsenide(Texas Tech University, 2003-05) Khawaja, Zahir KarimThere are many different means to characterize the semiconductor materials. Optical methods are of great significance because they are contactless, non-destructive and unambiguous. Photomodulated reflectance (PR) is one of such techniques. In this thesis, I describe the optical setup used for PR and a custom LabVIEW program to control the data acquisition. In addition to this, this program also analyzes input data and plots spectra in real time. PR spectra of GaAs and GalnAs were measured to verify proper function of the optics, electronics, and custom program. The experiment confirmed PR spectra could be measured from these samples at room temperature. The energy gaps measured were in the 1.405 to 1.43 eV range.Item The reflectance spectra of some heterogeneous materials(Texas Tech University, 1969-05) Richardson, John StuartNot available