Acousto-Optic Deflectors and Variable Frequency Shifters
A Bragg configuration gives a single first order output beam,
which intensity is directly
linked to the power of RF control signal, and which angle is
directly linked to the RF
frequency. By varying the frequency, the output laser beam
angle is modified. A deflector
is used to scan a laser beam over a range of angles, or to
control with accuracy the
output angle of the laser beam.
By varying the frequency, the first order beam is also
frequency shifted by the amount of
the RF carrier frequency : it acts like a variable frequency shifter.
The main parameters to qualify a deflector are
1.Deflection angle range and
2.Resolution. The deflection angle range is the maximum
angle variation of the laser
beam : it is linked to the frequency range of the device.
The resolution of a deflection is the number of distinct
directions which can be addressed
by the deflector : it is linked to the deflection angle range
and laser divergence.
Two deflectors can be used in series and at right angles to
give full two-dimensional scanning.