7
ISOMET
4.
INSTALLATION AND ADJUSTMENT
4.1
Connect cooling water to the RFA2120
Connect cooling water to the AO device.
Due to the high RF power dissipated in the AO modulator, it is paramount that the
device is operated only when water cooling is circulating.
For optimum AO performance ensure the flow rate is not less than 0.5 litres/minute
at < 25 degC
4.2
With no d-c power applied, connect the + 24V (or +28V) DC in to the center terminal of the
feed-thru terminal. DO NOT APPLY POWER.
4.3
Connect the RF output BNC jack to the acousto-optic modulator (or a 50
Ω
RF load, if it is
desired to measure the modulator RF output power).
4.4
Connect the Interlock of the acousto-optic modulator (SMA, SMC or mini 3pin connector) to
the enable inputs on the 9-pin D-type connector of the RFA. Connect pin 4 of ‘D’ to the centre
pin of the SMA/SMC and pin 5 of ‘D’ to the outer ground of the SMA.
The interlock connection becomes open circuit, disabling the RF output if the temperature of
the modulator exceeds 35ºC or the internal driver temperature exceeds 70ºC. LED indicator
illuminates when the Interlocks are closed and the RF is enabled (see Section 3). In addition,
a CMOS ‘interlock valid’ signal output is provided on pin 1 of the D-type connector for remote
monitoring purposes.
4.5
Adjustment of the RF output power is best done with amplifier connected to the acousto-optic
modulator. The Amplifier maximum output power is factory preset to approx 9W.
The optimum RF power level required for the modulator to produce maximum first
order intensity will be different at various laser wavelengths. Applying RF power in
excess of this optimum level will cause a decrease in first order intensity (a false
indication of insufficient RF power ) and makes accurate Bragg alignment difficult. It
is therefore recommended that initial alignment be performed at a low RF power level.
4.6
Locate the PWR ADJ access on the driver end plate.
