Wavelength-Agile Rayleigh Scattering by use of an Atomic Vapor Cell
Abstract
A wavelength-agile technique using an atomic vapor cell is developed and applied
to the measurement of Rayleigh scattering. The atomic vapor cell displays a steep
change in refractive index as a function of wavelength, thereby creating a wavelength
scan over a narrow spectral range. This scan can be utilized for high resolution spectral
measurements. For example, a short pulse duration laser was input into the cell and the
resulting wavelength-agile scan was used to resolve a single iodine absorption feature.
These measurements revealed that the atomic vapor cell distorts the input pulse shape and
therefore this technique must be used with care. A wavelength-agile scan of the Rayleigh
scattering spectrum was created using the atomic vapor cell; the resolved Rayleigh
scattering spectrum can be compared to theory to obtain the temperature, pressure, and
velocity of the scattering medium.
The overall goal of this research was to direct light scattered by the gas in a vortex
tube into the atomic vapor cell in order to create a wavelength-agile Rayleigh scattering
spectrum. The temperature, pressure, and velocity at the scattering location would be
resolved from the results of this time-of-flight technique. In this research only the
scattering in a fiber was measured due to experimental difficulties. The results of this
measurement indicate that this wavelength-agile Rayleigh scattering technique is
difficult. Rayleigh scattering is extremely weak and therefore difficult to measure while
the atomic vapor cell distorts the light passing through it.
Subject
University of Wisconsin--Madison. College of Engineering.
Thesis (M.S.)--University of Wisconsin--Madison, 2005.
Permanent Link
http://digital.library.wisc.edu/1793/6520Description
Pages: 198