Technical Center: Laser Glossary of Terms

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 a person may be exposed without hazardous effects 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 micro meter 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 distributed across the cross section of the beam. Also used to describe the operating mode of a laser such as continuous or pulsed.

Mode Locked

A method of producing laser pulses in which short pulses (approximately 10-12 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.