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Instructions for Use
Surgical Laser Unit Limax
4
Functional Principle
4.1
General Information on Laser Theory
LASER is an acronym meaning "Light Amplification by Stimulated Emission of Radiation".
The laser (light source) consists of an active medium and an excitation source. This excitation
source "pumps" the electrons of the active medium from their normal state into a stimulated
energy state (high energy level). The medium then starts to return to its normal state
(transition to lower energy levels). In this process, photons are emitted. The laser light is then
reflected multiply in an optical resonator (laser cavity) consisting of a highly reflecting mirror
and a partially transparent one. At the same time, it is amplified by stimulated emission while
traveling back and forth between the mirrors. Through the semitransparent mirror, part of the
laser light is coupled out and subsequently used for medical purposes.
Main characteristics of laser light:
Beam quality – high focusability thanks to low transversal mode number.
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Monochromaticity – light of a very narrow wavelength range, equivalent to a single color in
the spectrum of electromagnetic radiation.
Coherence – all photons emitted are in phase (in terms of both space and time).
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4.2
The Nd:YAG Laser
The Nd:YAG laser is a solid-state laser which emits high-intensity laser light at a wavelength of
1,320 nm (belonging to the near infrared range of the spectrum). The medium used is a
cylindrical YAG (yttrium-aluminum-garnet) crystal doped (mixed) with Nd
ions). The intensive light of laser diodes is used as an excitation/stimulation mechanism. The
wavelength of the light produced by the laser diodes matches perfectly with an excitation line
of the absorption spectrum of the Nd
power of the laser diodes allows for direct control of the output power of the Nd:YAG laser.
4.3
Fields of Application
The therapeutic effect produced by the continuous-wave Nd:YAG laser light is based on the
conversion of light energy into heat, a process that triggers both reversible and irreversible
tissue reactions (hyperthermia, coagulation, vaporization). The specific therapeutic effect of
this type of laser light mainly depends on the following 4 factors:
wavelength of the light
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power density (irradiation intensity)
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irradiation time (treatment/exposure time)
•
tissue characteristics
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Revision 5
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120
3+
ions of the YAG host crystal. Adjusting the output
3+
ions (neodymium
15
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