Page 123 - LASERS & IPLS IN MEDICAL/AESTHETIC APPLICATIONS

Glossary
Absorption
Absorption Coefficient
Accessible Emission Limit (AEL)
Administrative Control Measures
Aiming Beam
Average Power
Back-scattering
Beam
Beam Diameter
Beam Divergence
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. In the application of ‘Selective Photothermolysis’ we match the wavelength of the light to the absorption coefficient of the target chromophore, to maximise the amount of light energy absorbed.
The maximum accessible emission level limit (AEL) permitted within a particular class. 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 set of administrative procedures, training and warning signs designed to ensure safe and proper control of laser/IPL systems in a designated area.
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.
This is the total energy in a light exposure divided by the duration of that exposure, measured in Watts. Note that the ‘Peak Power’ (see below) can easily exceed the average power.
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 light 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...
Contrary to popular myth-conception, laser beams are not truly ‘parallel’. They do diverge over a distance. The divergence is the angle of beam spread measured in radians or milliradians (1
Chapter 1 – Fundamentals of Medical/Aesthetic Lasers and IPLs v1.1
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Chapter 1 LEVEL A Fundamentals of Lasers/IPLs
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