peter.king@LIGO.ORG - posted 13:25, Wednesday 28 August 2019 - last comment - 16:25, Wednesday 28 August 2019(51580)
Quick look at removed squeezer laser
I performed a cursory inspection of the Mephisto laser that was used in the squeezer (S/N 8552).
The output beam looked good with a beam profiler. The beam propagation was measured at its
factory set crystal temperature of 25.10 degC and the last used temperature, 33.00 degC
(see 8552Removed.png). The output beam pretty much remained the same at both temperatures.
With the diode current set to 2.15 A, the output of a spectrum was recorded for both
crystal temperatures. 25R10C.png shows the output when the crystal temperature was 25.10 degC.
33R00C.png when it was 33.00 degC. The presence of another mode is clearly seen. At the
higher temperature, the output power of the laser was ~10-15 mW higher and anecdotally seemed
a little less stable.
The crystal temperature was scanned, starting from 25.00 degC. The following regions are
where the multi-mode behaviour was observed.
- 28.90 to 29.75
- 32.48 to 33.35
- 35.9 to 36.7
Will check the behaviour for different diode currents next up.
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Comments related to this report
Checked the laser out at the last operated squeezer settings (tek00005.png). The laser was multi-mode, or mode hopping at the diode current of 2.025 A and crystal temperature of 31.68 degC. The laser was okay when the diode current was decreased to 1.980 A and down to 1,822 A, where the output power of the laser was ~740 mW and ~550 mW respectively. The laser was okay from 2.125 A to 2.250 A, where the output power was 895 mW and 960 mW respectively.
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