(b) The light source. A very bright light from a flash lamp is the light
source for solid rod lasers. The flash lamp works like a camera flashbulb, but it can be
used over and over.
(c) The power supply. The flash of light, the power supply, excites the
atoms in the rod giving each atom extra energy. The atom has to do something with
this extra energy in order to return to normal, so it throws off the extra energy as a small
bundle of light--a photon.
(d) Chain reaction/stimulated emission. The flash of light excites some
of the atoms causing them to throw off photons. Those photons bump into other atoms,
exciting them and causing them to throw off photons.
(e) The reflecting box. The photons must be made to move along the
center of the laser rod. To do this, put the rod inside a highly polished container called
a reflecting box. The photons will bounce off the inside of the container and land on the
(f) Mirrors. Put a mirror on either end of the reflecting box, one of the
mirrors being strong and the other weak.
(g) The laser beam. Eventually, the stored up photons will burst forth
through the end of the box with the weaker mirror, and this burst will be a beam of light--
a laser beam.
(h) Pulsed laser. In this type of laser, the beam of light bursts forth
quickly but lasts only a short time. Therefore, the flash lamp must be set off again to
create another beam. This pattern of setting off the flash lamp again and again is a
pattern like the human heart--pump, rest, then pump again. For that reason, this type of
laser is called a pulsed laser.
NOTE: The other type of laser beam is a continuous laser beam.
(i) Color. Laser light waves are monochromatic; that is, they are of a
single color. Actually, no light source is capable of producing light that is perfectly only
one color, but laser can produce such a light more closely than any other system.
(j) Laser beam strength. The strength of the laser beam varies,
depending on the type of laser system used. See figure 2-24.