These tutorials are designed to provide a fundamental overview of the theory behind common laser-based diagnostic techniques.
Light scattering by small spherical particles is most commonly characterized by the theories of Rayleigh and Mie. This paper summarizes the physics of light scattering, and presents the basic formulations. Several plots are included that portray the key characteristics of Mie and Rayleigh light scattering.
Rayleigh/Mie Light Scattering
Certain inelastic light scattering may be characterized by
the theories of C.V. Raman. Such scattering is referred to as
Raman scattering. This paper summarizes the physics of
Raman scattering, and presents the basic formulations. Several
plots are included that provide examples of Raman scattering
for gaseous, liquid, and solid samples.
LIBS module to be added soon.
See a video of laser-induced breakdown (LIBS) in ambient
air. This breakdown is created by a Q-switched, 1064-nm
Nd:YAG laser with a pulse energy of about 275 mJ and
an 8-ns pulse width. The laser is operating at 2 Hz.
Excimer laser tissue ablation module to be added soon.
The video below shows excimer laser ablation of a
bovine cornea. The 193-nm excimer laser is operating
at 400 Hz in a scanning mode that is used for many
LASIK and PRK procedures. The laser pulse energy
is 2.7 mJ/pulse. Although the 193-nm laser beam is
invisible, each laser pulse causes fluorescence, which
is visible in the video. The video frame exposure time
is such that 12-14 individual laser pulses are captured
in each frame. The cornea of a bovine eye is similar
to a human cornea, hence they make excellent
research samples. The video is representative
of a typical LASIK/PRK procedure.
The bovine eye in the video has been removed from the cow.
These eyes are obtained from a meat processing facility, and are
used under an approved protocol. These eyes are normally
discarded, and are made available to our research program.
Therefore, no animals were harmed for this project.