Today's models can produce beams ranging from infrared radiation through ultraviolet radiation. Infrared radition has longer wavelengths than those of visible light, and ultraviolet radiation has shorter wavelengths. Most of these lasers have controlled frequencies. Eventually neon atoms de-excite and radiate red photons. When the radiant energy passes other excited neon atoms, they become stimulated into emitting with the photons exactly in phase with the radiant energy that stimulated the emission.
Photons then pass out the tube in irregular directions, giving it a red glow.
The reflected photons stimulate the emission of photons from other neon atoms, producing the same frequency, phase, and direction. The photons fluctuate between the mirrors, becoming amplified with each pass. Figure 4 Is a Helium-neon laser. X-rays excite the innermost electrons of atoms, by jumping to the lowest state, and causing the electrons to actually suddenly stop, this produces the high frequecy x radiation. However even small dosages can effect the human body, they can cause mutations in some tissues in the body.