Q-Switch

A device that has the effect of a shutter to control the laser resonator's ability to oscillate. Control allows one to spoil the resonator's "Q-factor," keeping it low to prevent lasing action. When a high level of energy is stored, the laser can emit a very high-peak-power pulse.

Q-Switched Laser

A laser which stores energy in the laser media to produce extremely short, extremely high intensity bursts of energy.

Quantum Efficiency (QE)

The intrinsic ability of a detector to convert photons into electrons. It is the ratio of generated electrons to incident photons expressed as a percentage.

Quartz

The naturally occurring crystalline form of silicon dioxide. It is slightly birefringent and exhibits rotary dispersion of light rays transmitted along the crystal axis. Quartz transmits light from about 180 nm in the ultraviolet to 4.5 μm in the infrared. It is very hard and takes a high polish, and has a low thermal expansion coefficient. Crystalline quartz is used extensively in ultraviolet laser applications and for a variety of polarization components.