6
ISOMET
3.11
To equalise deflection efficiency at the extremes of the scan, alternate between the minimum
and maximum desired frequencies and adjust Bragg angle to give the same efficiency for
both.
The correct phase offset at each frequency must be applied
. (Note: the photo
detector or light power meter will require repositioning for the two angles.) Sweeping the freq’
input should result in a continuous deflected line output. If significant peaks and troughs are
noted across the sweep, it is probable that the phase shift between the RF channels is
incorrect for the Bragg orientation of the AO deflector.
The lead lengths between the two outputs of the RF driver and the beam steered deflector
should be equal unless otherwise instructed. Unequal lengths of more than a 1cm would
introduce a phase error.
Typical swept frequency response at 374nm
First order diffraction efficiency vs RF drive frequency
4.
MAINTENANCE
