Technical Center: Laser Glossary of Terms
Depth of Field
The working range of the beam in or near the focal plane of a lens; a function of wavelength, diameter of the unfocused beam, and focal length of the lens.
Depth of Focus
The distance over which the focused laser spot has a constant diameter and thus constant irradiance.
Filter that allows selective transmission of colors desired wavelengths.
Deviation of part of a beam, determined by the wave nature of radiation and occurring when the radiation passes the edge of an opaque obstacle.
Takes place when different parts of a beam incident on a surface are reflected over a wide range of angles in accordance with Lambert's law. The intensity will fall-off as the inverse of the square of the distance away from the surface and also obey a cosine law of reflection.
An optical device or material that homogenizes the output of light causing a very smooth, scattered, even distribution over the area affected. The intensity will obey Lambert's law. (See Diffuse Reflection.)
The increase in the diameter of the laser beam with distance from the exit aperture. The value gives the full angle at the point where the laser radiant exposure or irradiance is 1/e or 1/e2 of the maximum value, depending upon which criteria is used.
Measurement of the power, energy, irradiance, or radiant exposure of light delivered to tissue.
All undesirable variations in output (either amplitude or frequency).
Any unintended change in direction of the beam before, during, and after warm-up; measured in mrad.
Ratio of total "on" duration to total exposure duration for a repetitively pulsed laser.