(3) Dermatologist can use laser beams to remove marks on dark skin areas
since laser beam light is absorbed by dark areas. Therefore, persons with portwine
birth marks, tatoos, melanomas, and basal cell carcinomas can have these removed
with a Ruby laser.
h. Measuring the Environment. Lasers can be used to study and measure air
pollution. The Los Angeles basin is frequently plagued with photochemical smog.
Chemicals in the exhaust from automobiles, trucks, buses, etc., react with each other
and the oxygen in the air. They become attached to particles of dust or droplets of
water, causing smog. This type of pollution can be studied by drawing a sample of the
polluted air in a special measuring cell and scanning it with a tunable laser.
: Tunable lasers are lasers
in which the wavelengths
of laser light can
i. Air Turbulence Studies. Laser beams are used in determining the drag
coefficient on new cars. The drag coefficient refers to the amount of resistance an
automobile creates against the wind when the car is traveling at different speeds. The
goal is to design an automobile with as little resistance to wind as possible. The engine
of an automobile with a reduced resistance to wind does not work as hard as the engine
of an automobile with a higher resistance to wind. The result is that the first automobile
gets more miles to the gallon in gas mileage.
j. Holography. The word "holo" means whole and "graph" means picture.
Together they mean a picture of the whole thing which is what a holograph seems to
be--a three-dimensional picture. For example, a photograph taken of a tree shows the
tree in two dimensions--height and width, but not depth.
Figure 2-18. Two-dimensional photograph.