Feedback Controlyzer DigiLock 110
Page 50
Status: 5.12.17
The laser frequency can be adjusted to the desired resonance by several means with increasing preci-
sion:
• Coarse tuning in the 0.1 nm range - usually only required for the initial setup - can be achieved by
modifying the angle of the grating with the fine thread screw.
• Change the current (and if necessary the temperature) of the laser to tune the frequency and
achieve single mode operation.
• The built in piezo allows mode-hop-free scanning of the laser over several 10 GHz. The DigiLock 110
generates the scan signal that drives the piezo using the SC 110 as a high voltage amplifier. The
output is the sum of the voltage specified in the DigiLock 110 software and the offset of the SC 110.
The SC 110 offset can hence additionally be used to scan the laser.
7. In the Scan module of the DigiLock 110 you can choose the parameters for the scan signal gener-
ation:
Table 3 DigiLock 110 Scan Module Settings
The maximum scan range of the DigiLock 110 module is obtained in the following way:
8. Choose <SC 110 out> in the Offset tab (see Figure 10) of the of the DigiLock User Interface (DUI)
and set the Offset value to 0 V.
9. Set the Offset adjust ten-turn potentiometer on the SC 110 front panel to half the available output
range (“5“) which corresponds to an output voltage of 75 V. The DigiLock 110 software can now
access the full output range (0..150 V).
10. All the relevant signals can be analyzed through the DigiLock 110 computer interface. However,
the DigiLock 110 also provides a trigger output (TRIG) which can be used for monitoring with an
auxiliary external oscilloscope.
Now all the hardware is set up and the system can be completely controlled by the DigiLock 110 soft-
ware:
11. The photodetector signal connected to the Main in (4) connector on the DigiLock 110 front panel
can be examined in the Scope display (shown in the lower part of Figure 36).
Name Description Value to set to
1
1. The numerical values are guidelines and depend on the individual setup.
Signal type type of scan ramp triangle
Frequency frequency of full scan (back and forth) 10 Hz
Amplitude scan amplitude peak-peak 10 V
2
2. The scan amplitude can be enlarged or reduced to correspond to the application.
Output output to which the scan signal is added <SC 110 out>
CAUTION ! The SC 110 output can deliver high voltages (up to 150 V). Please make sure that your
oscilloscope has suitable inputs.
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