Page 127 - LASERS & IPLS IN MEDICAL/AESTHETIC APPLICATIONS

Monochromatic Light
Nanometre (nm)
Nd:YAG Laser
Nominal Ocular Hazard Zone
Optical Density
Phase
Photon
Photo- Mechanical Effect
Photo-Acoustic Effect
Photo-thermal Effect
not have derived his work on relativity without Maxwell’s work. See more here...
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.
A unit of length in the International System of Units (SI) equal to one billionth of a metre. Abbreviated ‘nm’ - a measure of length. One nm equals 10-9 metre, which is 0.000000001 metres, and is the usual measure of light wavelengths. Visible light ranges from about 400 nm in the purple to about 760 nm in the deep red.
Neodymium:Yttrium Aluminium Garnet. A synthetic crystal used as a laser medium to produce 1064 nm light.
The zone within which the level of direct, reflected or scattered laser radiation can exceed the MPE for that system. Proper protective equipment must be worn within this zone.
A logarithmic expression for the attenuation produced by an attenuating medium, such as an eye protection filter. It equals the logarithm, to the base 10, of the reciprocal of the transmittance at a given wavelength. It is usually denoted by ‘OD’. See more here...
Waves are in phase with each other when all the troughs and peaks coincide and are "locked" together. The result is a reinforced wave in increased amplitude (brightness).
In quantum theory, the elemental unit of light, having both wave and particle behaviour. It has motion, but no mass or charge. The photon energy (E) is proportional to the electromagnetic wave frequency (ν) by the relationship: E=hν; where h is Planck's constant (6.63 x10-34 Joule-sec).
The photo-mechanical effect is created when a very high temperature is generated but which is not sustainable, as in tissues. The energy within the heat is converted into a pressure wave which propagates through the tissue at the speed of sound. Anything brittle in its path will experience a shear force causing it to rupture – as in tattoo ink. Non-brittle elements within the skin will merely vibrate under such a force. This reaction typically occurs when the pulse duration of the laser is less than around 100 nanoseconds.
An alternative name for the Photo-Mechanical Effect, above.
This occurs when an object absorbs light energy and generates heat. Many everyday objects do this naturally from sunlight falling on them. Lasers with pulsewidths in the micro to millisecond ranges can easily induce the photothermal effects in tissues.
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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