ISOMET RFA2 1 Series, Instruction Manual

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14
ISOMET
RF
Pulse
AO crystal
Acoustic Wave
Active
Aperture
Height
Laser Beam
Active Aperture
Centre Line
H mm
X mm
d mm
Absorber
Bragg Pivot Point
Transducer
(V)
Y mm
B A
Appendix A: Beam Position
Timing Considerations for AO Devices in Pulsed Lasers Applications
When attempting to synchronize a pulsed laser beam with a pulsed RF acoustic wave in an AO
device, the designer must consider the transit time of the acoustic wave from the transducer to the
laser beam position. This is called the Pedestal delay .
Input Beam Location
Vertical axis: Place the laser beam at the centre of the active aperture at Y mm above the base.
Horizontal (Diffraction) axis: Place beam above the Bragg pivot point.
Timing considerations with respect to the RF modulation signal
An acousto-optic device is characterized by a travelling acoustic wave. This wave is launched from
the RF excited transducer and travels at velocity V across the laser beam and into the absorber.
It is important to consider this transit period when synchronizing a pulsed laser output with a pulsed
AOM/AOD driver signal.
Early/later refers to the laser trigger
timing relative to the RF driver
modulation signal