Page 118 - Chapter 3 - Fundamentals of Laser/IPL Hair Removal

Glossary
Absorption
Absorption Coefficient
Accessible Emission Limit (AEL)
Aiming Beam Back-scattering
Beam
Beam Diameter
Beam Divergence
Blink Response
Coherence
When light strikes any object part of the energy is retained by the object while the rest is reflected. This absorption process results in a transfer of energy from the photons into vibrational energy (heat) which can result in a temperature rise. See more here...
Factor describing light's ability to be absorbed per unit of path length.
The maximum accessible emission level limit (AEL) permitted within a particular class. In ANSI Z-136.1, AEL is determined as the product of Accessible Emission times the Maximum Permissible Exposure (MPE) using the area of the limiting aperture (7 mm for visible and near infrared lasers)
A laser (or other light source) used as a guide light. Used coaxially with infrared or other invisible light may also be a reduced level of the actual laser used for surgery or for other applications.
When light scatters in the dermis it changes direction after each event. In some cases, the change will re-direct it back out of the skin entirely. This is known as back-scattering. PA Torstensson calculated that a significant proportion of visible laser energy may be back- scattered out of the skin, due to the high number of scattering events in the dermis. See more here...
A collection of rays that may be parallel, convergent, or divergent.
The distance between diametrically opposed points in the cross section of a circular beam where the intensity is reduced by a factor of 1/e (0.368) of the peak level (for safety standards). The value is normally chosen at 1/e2 (0.135) of the peak level for manufacturing specifications. See more here...
Angle of beam spread measured in radians or milliradians (1 milliradian = 3.4 minutes-of-arc or approximately 1 mil). For small angles where the cord is approximately equal to the arc, the beam divergence can be closely approximated by the ratio of the beam diameter divided by the distance (range) from the laser aperture.
Closure of the eyelid, eye movement, pupillary constriction or movement of the head to avoid an exposure to a bright light source. The blink response to an exposure from a bright, visible, laser source is assumed to limit the exposure of a specific retinal area to 0.25 seconds or less. It is an automatic reaction to bright light.
A term describing light as waves which are in phase in both time and space. Monochromaticity and low divergence are two properties of coherent light.
Chapter 3 – Fundamentals of Laser/IPL Hair Removal 1st Edition
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