 |
Dhiraj K. Sardar
Professor
Ph.D., Oklahoma State UniversityLasers, modern
optics, spectroscopy, and applications to optical
characterizations of biological materials.
|
Research
Our students and I are actively involved in the
investigation of optical properties of a variety of
technologically important materials using high
resolution laser spectroscopy techniques. Our main
objectives are to characterize these materials, and
discover and understand the fundamental physical
mechanisms such as energy transfer, fluorescence
quenching, nonradiative relaxation, electron-phonon
interaction, etc. The experimental measurements include
absorption, excitation, emission, and fluorescence
lifetimes of electronic transitions at various physical
conditions. We are also pursuing the spectroscopic and
laser studies on solid-state tunable dye lasers. Several
solid-state dye laser materials have been developed in
our laboratory from HEMA and appropriate
curing agent with Bimane as well as Pyromethene-BF2
dyes. We have been able to observe lasing in these
materials. Although the thermal effect in these plastic
hosts is major concern, currently, we are hopeful that
better host and curing agent for the dyes will be found
and also better operating design will be possible in
order to remedy the thermal stress.
Currently, we are also investigating the optical
properties of biological tissues as well as studying the
laser-tissue interaction, an exciting area of
biophysics. Since the Beer's law only applies to the
special situation where the absorption dominates the
scattering, this law cannot be used in the case of
turbid media such as tissue, where scattering is a
dominant factor with the exceptions being limited to
certain wavelengths. Therefore, optical absorption
measurements using spectrophotometer alone is not
sufficient to accurately determine the absorption
coefficient which is a critical parameter for
laser-tissue interaction, in general, and particularly,
for laser surgery. Thus we are employing other
instruments such as optical integrating sphere to
measure transmission and reflection that will help
us deduce the absorption and scattering coefficients. In
our studies, we apply Chandrasekhar’s radiative
transport equation and the Kubelka-Munk theory to better
understand our observed data. We are also employing the
algorithm known as Inverse Adding and Doubling (IAD)
method as well as Monte Carlo technique to characterize
the optical properties and distribution of photons in
biological materials.
Teaching
All undergraduate lower and upper division courses.
Among the graduate courses are solid state physics,
lasers: theory and applications, optical and laser
spectroscopy, biophotonics, atomic spectroscopy, group
theory, and quantum mechanics.
Selected Papers
- Sardar, D.K. and F.S. Salinas*, “Optical
Properties of a Laser Dye in a Solid State Polymeric
Host,” Journal of Applied Physics, Vol. 91, 9598-9602
(2002).
- Sardar, D.K., M.L. Mayo*, and R.D. Glickman,
"Optical Characterization of Melanin," Journal of
Biomedical Optics, Vol. 6, 404-411 (2001).
- Sardar, D.K. and S.C. Stubblefield*, "Phonon
Effects on Sharp Spectral Lines for Inter-Stark
Transitions of Trivalent Neodymium Ions in Strontium
Fluorovanadate," Physical Review B, Vol. 60,
14724-14731 (1999).
- Sardar, D.K. and L.B. Levy*, "Optical Properties
of Whole Blood," Lasers in Medical Sciences, Vol. 13,
106-111 (1998).
*student author
Center for
Lasers and Materials Science Research
Last update:
Wednesday May 11, 2005 |
