OBJECT The subject matter or figure imaged by, or seen through, an optical
OPACITY The condition of being non-transparent.
OPEN INSTALLATION Any location where lasers are used which will be open to
operating personnel during laser operation and may or may not specifically restrict
OPERATION The performance of the laser or laser system over the full range
of its intended functions (normal operation). It does not include maintenance
or services as defined in this glossary.
OPTIC DISC The portion of the optic nerve within the eye which is formed by
the meeting of all the retinal nerve fibers at the level of the retina.
OPTICAL CAVITY (Resonator) Space between the laser mirrors where lasing actionoccurs.
OPTICAL DENSITY A logarithmic expression for the attenuation produced by an
attenuating medium, such as an eye protection filter.
OPTICAL FIBER A filament of quartz or other optical material capable of transmitting
light along its length by multiple internal reflection and emitting it at the
OPTICAL PUMPING The excitation of the lasing medium by the application of light
rather than electrical discharge.
OPTICAL RADIATION Ultraviolet, visible and infrared radiation (0.35-1.4 m)
that falls in the region of transmittance of the human eye.
OPTICAL RESONATOR See Resonator.
OPTICALLY PUMPED LASERS A type of laser that derives energy from another light
source such as a xenon or krypton flashlamp or other laser source.
OUTPUT COUPLER Partially reflective mirror in laser cavity which allows emission
of laser light.
OUTPUT POWER The energy per second measured in watts emitted from the laser
in the form of coherent light.