Day: April 6, 2011

LASER

Four level laser

In the four level laser system, the atoms from ground state E1 are raised to excited state E4 with the help of pumping. From the

LASER

Three level lasers

In the three level laser system, the atoms are pumped from the ground state E1 to higher state E3 with the help of pumping source.

LASER

temporal and spatial coherence

Coherence can be classified into two ways: a) temporal coherence: consider a light wave traveling along +X axis. Consider two different points A and B