Tsunami - Beckman Institute Laser Resource Center

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Figure 4-6: Model 3955 Electronics Module Rear Panel Controls and Connections
Controls, Indicators and Connections
Fine PHASE control-adjusts the phase relationship between the AOM
signal and the photodiode signal to provide a pulse-locking mechanism.
Its adjustment range is about 100 ps. Adjust this control to sync the mode
locker to the pulse rate.
NOTE: If you use cables other than those shipped with the system, or if
you convert from a ps to a fs configuration, or vice versa, or convert from
extra-long (X) to standard (S) wavelength, or vice versa, the phase signal
may move outside the 100 ps range of this control. If this happens, you
need to adjust the coarse control located inside the Model 3955. Refer to
"Coarse Phase Adjustment ..." at the end of chapter 6.
POWER: ON indicator-indicates power is applied to the Model 3955
electronics module, the AOM heater and GTI heaters, and that high voltage
is applied to the GTI. The GTI is present only in the ps configuration.
Rear Panel
The following is a description of the connections and switches on the
Model 3955 electronics module rear panel. Refer to Figure 4-6.
PHOTODIODE BNC connector-receives the control signal from the
laser head photodiode. It attaches to the ML PD photodiode connector on
the right side of the laser head input bezel. Do not attach it to the LTC PD
connector! The three BNC connectors on the laser head provide different
output signal levels that can damage the receiving device if they are
connected to the wrong receiver. Use the MONITOR connector on the rear
panel to monitor this signal on an oscilloscope or frequency counter. Use
the SYNC output (sinewave) to trigger the oscilloscope.
MONITOR BNC connector--connects to a frequency counter or to a 50 Q
oscilloscope input for monitoring the laser head photodiode signal. A
typical waveform is shown in Figure 4-7. Use the SYNC output (sinewave)
to trigger the oscilloscope.
f >
a
a
240V 0
<
0 0 0
[n]r>[x)
\u \\ \\ \\
0 ( , 10
TO HEAD
\\
\\\ul
Power Line
Photodiode Monitor Sync Mode Main Signal
Connector Connector Connector Locker Connector Connector and
Connector To Head OnIOff Switch
/