Ruby Laser its Construction and Working
Ruby laser construction and working, It is the first operating laser using three energy levels scheme of population inversion and a solid-state crystal laser element. The laser has three components Laser medium: it is in the form of a rod of the ruby crystal
Pumping process: The optical pumping; a helical xenon flash lamp
Resonator cavity: it is made of a full reflector and a partially reflecting plates parallel with high accuracy
Ruby laser is the three energy levels in which Argon atoms are excited by the optical pumping process, the population inversion is achieved between the metastable and ground states.
Ruby laser is made up by a crystal of Aluminium oxide (Al2O3) in which chromium oxide is mixed as impurity so that some of the Al3+ ions are replaced by Cr3+ ions. Chromium ions with a concentration of about 0.05% by weight. The cylindrical Ruby rod having length size 2 to 30 cm and 0.5 to 2 cm in diameter. Flat end faces A and B of the rod are perfectly parallel, face A is fully reflector and B is partially reflector.
The Ruby rod is arranged at the central axis of the xenon flash tube. The flash tube is made to flash for a few milliseconds to pump the chromium atoms. The road is surrounded by liquid nitrogen or water circulation tube to cool it. Light from the flash tube (green and blue color; 4500A0 and 5500A0 respectively) is made to fall upon the ruby rod, the chromium atoms absorb it and go into the excited state E21 and E22.
The xenon flash is of several milliseconds while the laser pulse is less than milliseconds. Ruby laser is a pulsed laser.