The
first stage:
Mohammed Hamza
LASING ACTION
When light travels
through a material, part of the light energy is absorbed by the atoms in the material.
The amount of light absorbed is dependent upon the characteristics of the
material and its thickness. Optical components, such as lenses and windows, are
made of materials that absorb very little of the light energy in the wavelength
region within which they are designed to function. Optical filters are designed
to transmit only a particular portion of the light that strikes them. They may
attenuate some wavelengths or eliminate some selected wavelengths, and transmit
the remaining ones with no change. The absorption of light is a critical
process in the optical pumping of solid and liquid lasers.
When a laser beam passes through the active medium of a
laser, energy is added to the laser beam through a process called "optical
gain."
This module discusses the absorption of light by materials
and the gain of a laser medium. The similarities of these two processes are
examined, and both are
measured experimentally in the laboratory.
ATTENUATION
OF LIGHT:
Figure 1 depicts a
beam of light traveling through a piece of optical material. Some of the light
energy is absorbed by the material, and
Fig. 1 Attenuation of a light beam
The
transmission of the optical material
is given by Equation 1.
Equation 1