The document describes the components and operation of a ruby laser, which was the first successful laser developed by Maiman in 1960 and consists of a cylindrical ruby rod surrounded by a flash tube that optically pumps the rod. The ruby rod contains chromium ions that are excited to a higher energy level by the flash tube and achieve population inversion, leading to stimulated emission and the production of coherent laser light pulses at 694.3nm wavelength through a process of photon reflection and stimulated emission within the rod. Key characteristics of the ruby laser output include monochromaticity, directionality, spatial and temporal coherence, and brightness.

1. Ms. T. Manonmani
Asst. professor of
physics

2. INTRODUCTION
 A ruby laser is a solid-state laser.
 Ruby laser is the first successful laser
developed by Maiman in 1960.

3.  Ruby laser – consists – cylindrical rod-
optically flat and accurately parallel.
 One end – fully silvered – other is partially
silvered.
 Ruby rod – surrounded by a glass tube.
 Glass tube – surrounded by a helical xenon
flash tube – acts – optical pumping system.

6.  Ruby rod- aluminium oxide (Al2O3) – doped with
0.05%chromium oxide Cr2O3.
 Aluminium atoms in the crystal lattice – replaced
by Cr3+
 Cr ions exited from level E1 to E2 - by
absorption of light of wavelength 550nm – from
xenon flash tube.
 Excited ions – nonradiative transitions with a
transfer of energy - level E2 – meta stable state
– lifetime – 3×10-3 s.

7.  Population of E2 level – greater than level E1.
 Population inversion is achived.
 Some photons – produced by sponteneous
transition from E2 to E1 - wavelength 694.3nm.
 Ruby rod – acts – reflecting mirror.
 Photons – not moving parallel to ruby rod – but
reflected back and forth.
 These stimulate the emission of similar other
photons.

8.  Chain reaction – develops – beam of
photons – moving parallel to rod –
monochromatic and coherent.
 All chromium ions – metastable level –
returned – ground state – laser action stop.
 Send – one more flash of pumping radiation
– through the rod.
 Ruby laser – operates – only in pulses.

10.  Monochromaticity
 Directionality
 Spatial Coherence
 Temporal Coherence and Brightness.