13
ISOMET
Schematic of a single electrode acousto optic deflector
and tunable driver
RF
1st Order Scan
0th Order
Input Laser Beam
Intensity Modulation
Tuning Voltage
θ
θ
θ
SEP
SCAN
BRAGG
AO Deflector
Deflector Driver
The input Bragg angle, relative to a normal to the optical surface and in the plane of deflection is :
θ
BRAGG
=
λ.
fc
2.v
The separation angle between the zeroth order and mid scan point of the first order is :
θ
SEP
=
λ.
fc
v
The first order scan angle is :
θ
SCAN
=
λ.δ
f
v
where:
λ
= wavelength
fc = centre frequency e.g. 110MHz / 120MHz / 140MHz
v = acoustic velocity of interaction material
= 5.7mm/usec (a-Quartz)
d = 1/e
2
beam diameter
Figure 5. Deflection System
