THEORY OF OPERATION
4-28
Versapulse Select Service Manual
0621-499-01 01/94
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PRIMARY BEAM PATH - the servo positioned mirror output is directed through two folding
mirrors towards the fiber focusing lens. In its path are the following additional optical components.
First Wedge Optic - The wedge optic front and back surfaces each reflect a small portion (≈
0.2%) of the YAG energy back towards an imaging mirror. The imaging mirror is positioned
to direct these reflections upon two pyrodetectors mounted on the Single Solenoid PCB, one
sample to each pyro. The pyro circuitry translates the energy sample into a voltage
proportional to the energy of the Ho:YAG pulse. To maximize the accuracy of the energy
sampling the wedge optic uses a simple coating and a near normal pick off angle. The
imaging mirror maintains a constant image size on the pyrodetector surface over the range of
beam diameters (the beam diameter decreases at higher pulse energies).
Low Power Attenuator - The LP attenuator can be inserted into the beam path to decrease
the treatment beam power. This allows the system to deliver pulse energies lower than the
lowest stable pulse energy available out of the YAG head. Currently the low power
attenuator feature is not implemented by the software.
Second Wedge Optic - A second wedge optic is required to check the power after the low
power attenuator. Although two samples are reflected off the wedge, only one is used. An
imaging mirror directs the sample towards a pyrodetector mounted on the Dual Solenoid
PCB. The pyro circuitry translates the energy sample into a voltage proportional to the
energy of the Ho:YAG pulse.
Service Attenuator - The service attenuator is inserted into the beam path to attenuate the
treatment beam before it is focused into the end of the fiber. It is operated by a switch inside
the unit accessible to the servicing technician. The attenuation is used during alignment
procedures. The system will not operate in user mode if the service attenuator is in the beam
path.
Safety Shutter - Blocks the treatment beam path when de-energized.
Aiming Beam Diode and Combiner Optic - A red (650 nm) aiming beam is provided by a
diode laser mounted in the optical head. The user can turn the aiming beam of or select high,
low, or medium intensity. The diode output is directed by a folding mirror to a beam
combiner in the primary beam path. The combiner and folding mirror are both adjustable to
allow for placing the diode aiming beam coaxial with the treatment beam.
Fiber Focus Lens - Focuses the beam into the fiber.
Blast Shield - Protects the Fiber Focus Lens from debris ejected from the proximal end of the
fiber during a fiber failure.
12/95
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