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R&D (Cryogenic)
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SatoshiTanioka - 09:14, Monday 22 July 2019 (1495)Get code to link to this report
PDH lock

This morning, I again tried to lock TEM00 mode.
The attached picture shows when the laser seemed locked (the label is same as before).
It seemes something is fed back to the laser, and it last several tens of seconds.
Actually, it is oscillating, and the dip is so small, so it needs to improve the alignment, gain, and some other things for more stable lock.

Images attached to this report
1495_20190722014848_20190722lock.jpg
Comments related to this report
SatoshiTanioka - 18:31, Tuesday 23 July 2019 (1502)

I tried to improve the lock stability by adjusting the gain of SR560.
However, I could not improve so much.
In the end, the lock last only 0.5sec.

So we need circuits for feedback control to achieve stable lock.
Anyway, we can lock the laser to temporal silicon cavity.

SatoshiTanioka - 19:33, Monday 22 July 2019 (1497)

I reduced the gain to 2*10^2, and tried to lock.
The oscilation was improved than higher gain one, but the lock last only 0.1sec and DC REFL dip was ~0.1mW.

Anyway, it seems that it is possible to lock TEM00 mode.
Actually, feeding back to laser PZT induces laser power fluctuation.
Therfore, ISS is needed in this experiment.