MAINTENANCE Performance of those adjustments or procedures specified in user
information provided by the manufacturer with the laser or laser system, which
are to be performed by the user to ensure the intended performance of the product.
It does not include operation or service as defined in this glossary.
MAXIMUM PERMISSIBLE EXPOSURE (MPE) The level of laser radiation to which person
may be exposed without hazardous effect or adverse biological changes in the eye
or skin.
MENISCUS LENS A lens which has one side convex, the other concave.
METASTABLE STATE The state of an atom, just below a higher excited state, which
an electron occupies momentarily before destabilizing and emitting light. The
upper of the two lasing levels.
MICROMETER A unit of length in the International System of Units (SI) equal
to one-millionth of a meter. Often referred to as a "micron".
MICRON An abbreviated expression for micrometer which is the unit of length
equal to 1 millionth of a meter. See MICROMETER.
MICROPROCESSOR A digital chip (computer) that operates, controls and monitors
some lasers.
MODE A term used to describe how the power of a laser beam is geometrically
distributedacross the cross-section of the beam. Also used to describe the operating
mode of a laser such as continuous or pulsed laser.
MODE LOCKED A method of producing laser pulses in which short pulses (approximately10-12
second) are produced and emitted in bursts or a continuous train.
MODULATION The ability to superimpose an external signal on the output beam
of the laser as a control.
MONOCHROMATIC LIGHT Theoretically, light consisting of just one wavelength.
No light is absolutely single frequency since it will have some bandwidth. Lasers
provide the narrowest of bandwidths that can be achieved.
MULTIMODE Laser emission at several closely-spaced frequencies.
