Model N-STP Operation Manual
4.2.5. Output Adjust
A multi-turn potentiometer is accessible from the front right side of the adapter, see
Figure 1-5.
Adjustment should only be made with a plastic tuning screwdriver.
Full clockwise (CW) adjustment will increase the output power to typically 1.05mW
for the N-STP-912 or 0.7 to 0.9mW for the N-STP-910 or within 400MHz of the center
line frequency, see Sections 7.0 and 8.0. Full counter-clockwise (CCW) adjustment will
decrease the output power to typically 0.5mW for the N-STP-912 or 0.35mW for the
N-STP-910, see Sections 7.0 and 8.0 for how this adjustment affects the optical
frequency. Each direction is torque protected (associated with a clicking sound) so
that further rotation will result in no power change.
4.2.6. Principle of Operation
The N-STP single frequency laser system works on the principle that a Doppler
Broadened TEM
00
output mode can be varied in power and frequency if the cavity
length (distance between laser mirrors) can be controlled. In most single frequency
lasers, heat conduction is used (usually over the entire cavity length) to expand and
thus control the cavity length. The N-STP lasers are unique in that they use induction
heating to control the length of a specially designed mirror mount structure. In this
way, a much smaller package can be accommodated, and more importantly, this
technique allows for faster servo response Figure 1-4 depicts the schematic block
diagram of the induction servo control circuit.
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IMPORTANT
