Tsunami - Beckman Institute Laser Resource Center

Tsunami
To ensure the Tsunami laser can be tuned over its wavelength range with a
fixed repetition rate, it is necessary to have a coarse cavity length adjust- -
ment in addition to the fine length control provided by the PZT-controlled
M4 mirror. Thus, mirror MI is mounted on a motorized micrometer and
controlled through upldown buttons on the Model 3930. The MI control is
a manual coarse control, while M4 is an automatic fine control. A bar
graph indicator on the Model 3930 indicates the relative position of M4.
The electronics module also provides controls and indicators for setting
and viewing the photodiode signal level and the reference frequency. A
built-in 10 Hz sweep generator can be used to create a 2 ns phase shift in
the Tsunami photodiode signal. This facilitates locating pulses when
trying to lock the LTC Tsunami to another laser.
System Controls
The following describes the displays and controls on the front and rear
panels of the Tsunami Model 3930 LTC electronics module.
Front Panel
TIMING coarselfine control-sets timing between the reference source
and the Tsunami laser. Both the coarse (outer knob) and fine (inner knob)
controls have a 10-turn resolution. Range for the coarse control is approximately
2 ns; it is 100 ps for the fine control. When the sweep generator
(see below) is off, the coarselfine controls set the timing reference; when
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the sweep generator is on, the coarselfine controls are disabled.
TIMING sweep generator onfoff push button-toggles the triangle wave
sweep generator on and off (default = off). The sweep runs at about 10 Hz,
and produces a linear timing change of about 2 ns. When the generator is
off, the coarselfine controls set the timing reference; when on, the coarse1
fine controls are disabled.
LEVEL indicator-displays relative photodiode signal strength with
full-scale = maximum signal. This is an uncalibrated reference indicator.
f ,
LEVEL FREQUENCY STATUS
@ Spectra-Physics 'I
Figure 8-2: Model 3930 Electronics Module Front Panel Controls and Indicators