Not logged in
Thu Oct 10 22:11:53 2019
Trans QPD checkout
I removed the flip-mount that was installed on the EY in-air table for the mode-spectroscopy project (see
). The Transmon QPD at EY sees IR light again.
Dark noise checkout - see
For the current config, let's say 0.8 W reaches the PRM, and we will have a PRG of 50.
circulating power in the arms.
will get transmitted through the ETM, of which at most half makes it to the QPD.
In the nominal operating condition, we expect more like 6 W circulating in the arm cavity. So something like 30uW is expected to make it out onto the Trans QPDs.
But in this condition, we expect to run with the high-gain Thorlabs PD.
In reality the number is likely to be somewhat smaller. But we should set the transimpedance gain of this photodiode accordingly. Currently, there are a bunch of ND filters installed on this photodiode, which probably should be removed.
The other purpose these QPDs are expected to serve is to stabilize the angular motion of the cavities when locked with high circulating power.
Need to calculate what the sensing noise requirement is.
Uploaded Thu Oct 10 23:12:57 2019
Uploaded Thu Oct 10 23:14:19 2019