3.1 Laser and controller configuration 21
3.1.2 DLC configuration
Although the FSC can be configured for either internal or external
sweep, it is significantly simpler to use the internal sweep mode and
set the DLC as a slave device as follows:
• Connect the “SLOW OUT” of the FSC to the “SWEEP / PZT MOD”
input of the DLC.
• Set DIP9 (“External sweep”) of the DLC to enabled. Ensure
that DIP13 and DIP14 are off.
• Set DIP3 (“Bias generation”) of the FSC to disabled
2
.
• Set SPAN on the DLC to maximum (fully clockwise).
• Set FREQUENCY on the DLC to zero (using the LCD display to
set “Frequency”).
• Ensure that SWEEP on the FSC is “INT”.
• Set FREQ OFFSET to mid-range and SPAN to full on the FSC
and observe the laser scan.
• If the scan is in the wrong direction, invert DIP4 of the FSC or
DIP11 of the DLC.
It is important that the SPAN knob of the DLC is not adjusted once
set as above, as it will impact the feedback loop and may prevent
the FSC from locking. The FSC controls should be used to adjust the
sweep.
2
The DLC automatically generates the current feed-forward (“bias”) from the
sweep input, so it is not necessary to generate a bias within the FSC.
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