How Lasers Work

Ruby Lasers

A ruby laser consists of a flash tube (like you would have on a camera), a ruby rod and two mirrors (one half-silvered). The ruby rod is the lasing medium and the flash tube pumps it.

1. The laser in its non-lasing state


2. The flash tube fires and injects light into the ruby rod. The light excites atoms in the ruby.


3. Some of these atoms emit photons.


4. Some of these photons run in a direction parallel to the ruby's axis, so they bounce back and forth off the mirrors. As they pass through the crystal, they stimulate emission in other atoms.


5. Monochromatic, single-phase, columnated light leaves the ruby through the half-silvered mirror -- laser light!