Three main components of laser device are:

a)      Active medium:

For example in ruby laser, the active medium is aluminum oxide doped with .05 percent of chromium ions.

In helium -neon laser it is the combination of helium and neon in the ratio of 10 :1.

b)      Pumping source:

For example in ruby laser, the pumping source is optical pumping that is helical xenon flash tube.

In helium-neon laser, electrical pumping that is electric discharge is used for stimulated absorption.

c)      Optical resonator system:

In most of the systems, it consists of system of two mirrors. On mirror is fully reflective and other is partially reflective.