| 1. High-voltage electricity causes the quartz flash
tube to emit an intense burst of light, exciting some of the atoms in the
ruby crystal to higher energy levels. |
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| 2. At a specific energy level, some atoms emit particles
of light called photons. At first the photons are emitted in all directions.
Photons from one atom stiumulate emission of photons from other atoms and
the light intensity is rapidly amplified. |
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| 3. Mirrors at each end reflect the photons back and
forth, continuing this process of stimulated emission and amplification. |
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| 4. The photons leave through the partially silvered
mirror at one end. This is laser light. |
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