The vast majority of dye lasers traditionally have been sold for research
and development, but applications in medical treatment are increasing
rapidly. A few dye lasers are used for other applications, including
medical diagnostic measurements, other types of inspection. and
entertainment displays.
The major scientific applications of dye lasers are in spectroscopy
and other types of measurement, both in the time and frequency (or
wavelength) domains. The ability to tune dye laser wavelength and
limit emission to a narrow spectral bandwidth makes dye lasers
extremely useful for studying the absorption and emission of light by
various materials, Although other light sources can be used in
spectroscopy, dye lasers offer higher light intensities in narrower
spectral bands than do other tunable, nonlaser sources. They have been
particularly useful in the study of atomic and molecular physics, and in
stimulating fluorescence. Dye lasers can be precisely tuned to match
specific absorption and emission bands, allowing atoms to be slowed
down to speeds equivalent to temperatures below 1 kelvin (K).
Ultrashort picosecond and femtosecond pulses from dye lasers have
been invaluable in studies of time response, such as measurements of
excited-state lifetimes and decay rates. Ultrashort pulses have been
used to study semiconductor properties, chemical reaction kinetics,
photosynthesis, time-resolved spectroscopy, and biomolecular
processes. The scope of these time and frequency domain studies is far
beyond the realm of this book.
In medicine, dye lasers are used to treat skin disorders and to
shatter stones in the urinary system and gall bladder. Dye lasers can be
built to emit at lines which are strongly absorbed in the target tissue,
such as the dark birthmarks called “portwine stains,” which are caused
by surface networks of abnormal blood vessels. Selection of the proper
wavelength causes the laser energy to concentrated in the target tissue,
while doing minimal damage to surrounding tissue. Dye laser light can
be directed through an optical fiber and delivered inside the body to
shatter solid stones in the kidneys and gall bladder; a series of laser
pulses generally can reduce the stone to fragments small enough to be
passed naturally from the body. Such treatment has gained rapid
acceptance because it avoids the need for surgery. Some dye lasers are
used for diagnostics, such as cell sorting. Dye lasers have also been
studied for treatment of cancer and eye disease.
Dye lasers have been considered for some measurement and
inspection applications requiring specific wavelengths, but at this
writing no such applications have gained wide acceptance. The cost and
complexity of dye lasers have helped to limit such uses.
Dye lasers have sometimes been used for displays because they can
generate varicolored beams. Although dye lasers offer a unique way to
scan the entire visible spectrum, their practical display applications are
limited by their operational complexity and high cost.
The tunability of dye lasers makes them attractive for photochemical
processing techniques in which the product depends critically on
wavelength. The most important such process in development is the
enrichment of isotopes, based on tuning a dye laser so that its output
excites one isotope but not the slightly shifted lines of a second.
Throughout the 1980s, the Lawrence Livermore National Laboratory
conducted two parallel programs using highpower dye lasers pumped
by copper vapor lasers. One uses the dye lasers to ionize uranium-235
(235U), but not the more common uranium-238 (238U). Collection of the
ionized material yields uranium enriched in the fissionable 235U, as
required for nuclear reactor fuel. Livermore also developed a process to
purify plutonium produced in nuclear reactors for use in nuclear bombs
by removing certain isotopes. At this writing, neither process is
operating on a commercial scale.
The vast majority of dye lasers traditionally have been sold for research
and development, but applications in medical treatment are increasing
rapidly. A few dye lasers are used for other applications, including
medical diagnostic measurements, other types of inspection. and
entertainment displays.
The major scientific applications of dye lasers are in spectroscopy
and other types of measurement, both in the time and frequency (or
wavelength) domains. The ability to tune dye laser wavelength and
limit emission to a narrow spectral bandwidth makes dye lasers
extremely useful for studying the absorption and emission of light by
various materials, Although other light sources can be used in
spectroscopy, dye lasers offer higher light intensities in narrower
spectral bands than do other tunable, nonlaser sources. They have been
particularly useful in the study of atomic and molecular physics, and in
stimulating fluorescence. Dye lasers can be precisely tuned to match
specific absorption and emission bands, allowing atoms to be slowed
down to speeds equivalent to temperatures below 1 kelvin (K).
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