User's Manual

Lumenis
®
Pulse
TM
50H / 100H Laser Systems Chapter 2: Theory of Operation
UM-20006520DE, Rev. A Page 12
Chapter 2: Theory of Operation
A laser, an acronym for Light Amplification of Stimulated Emission of
Radiation, produces a highly concentrated beam of light of a given
wavelength. Laser energy is generated by converting electrical energy to
light energy using a flashlamp. The flashlamp energy is then used to
excite the lasing medium, in this case a holmium YAG crystal rod. The
laser energy is amplified in the laser resonator cavity and a small portion
of the energy is allowed to leak out as the laser working beam.
The Pulse 50H or 100H holmium laser system emits a laser beam at a
wavelength of 2100nm. This wavelength is strongly absorbed by water in
tissue. Since soft tissue is comprised primarily of water, holmium laser
energy can be used effectively for excision, incision, ablation, and
vaporization when in direct contact with soft tissue and for coagulation
when in near contact with soft tissue. Calculi (stones) also contain a
sufficient amount of water that absorbs the laser energy leading to
lithotripsy.
When working in liquid environment the holmium laser energy provides
additional safety, since laser energy will be absorbed by the surrounding
liquid, limiting its reach to non-target tissue.
The holmium laser wavelength falls in the near-infrared region of the
electromagnetic spectrum. This wavelength is invisible to the human eye.
Therefore, a low-power, visible aiming beam is used to verify the laser’s
target tissue.
Laser Power Parameters
Tissue laser interaction is primarily governed by the laser wavelength and
the target tissue absorption coefficient at that wavelength, defining the
effectiveness of the laser energy absorption in the target tissue. However
additional characteristics of the specific laser system affect the laser tissue
interaction.
Pulsed lasers (such as the holmium laser) deliver an average power
(measured in Watts) that is achieved by multiplying the laser energy
emitted during each pulse (measured in Joules) and the frequency at
which these pulses are delivered (measured in Hertz).
The Lumenis Pulse 50H or Pulse 100H can deliver a maximum average
power of 50W or 100W respectively obtained, i.e., by delivery of 2 x 25 Hz.