5
ISOMET
3.6
If fitted, remove the PWR ADJ snap-in plugs from the driver case (see fig 1).
The PWR ADJ pot is a multi-turn type. Minimum power is when fully anti-clockwise (CCW).
With an insulated alignment tool or screwdriver:
Rotate the PWR ADJ potentiometer CCW at least 11 turns, then CW approx 5 turns.
3.7
Apply +15V, + 24V, or +28V DC power to the driver as appropriate for the model.
(see Section 1 and driver test sheet)
3.8
a)
Apply a constant ‘High’ TTL input level to
D-mod
(> 2.7V, 10mA drive capability).
b) Apply a constant 5V “DC” input level to
A-Mod
(15mA drive capability).
3.9
Observe the diffracted first-order output from the acousto-optic modulator and the undeflected
zeroth order beam. Adjust the Bragg angle (rotate the modulator) to maximise first order
beam intensity.
Note: the diffraction efficiency may not exceed 20-30% at this point in the alignment
procedure.
3.10
After the Bragg angle has been optimised, slowly increase the RF power (rotate PWR ADJ
CW) until maximum first order intensity is obtained. This peaked RF drive level is termed the
saturation power; Psat. For applications using a well focussed input beam into the AOM, the
correctly adjusted Bragg angle condition is indicated when the zero order shows a
characteristic dark line through the middle of the beam at or near the Psat drive level.
The driver is now ready for use.
