Georgia, Camilla, Sheila
We went to HAM7 this afternoon to do a few wrap up tasks.
Because the pump fiber chain transmission seems low (61375 and 61282), we rechecked this. We unplugged, inspected and cleaned the fiber on the inside of SQZT0 at the table panel coupler, although on reinspection the cleaning didn't make a difference. We unplugged the long in air fiber from the flange, inspected and cleaned that using both the neoclean tool recomended by diamond and then again using a figure 8 and vectra alpha wipe. This didn't improve. Camilla took a photo of this fiber using the fiber microscope. Finally, we unplugged the long in air fiber from the SQZT0 coupler, inspected it but decided not to clean it. Once we plugged this back in we saw a slight improvement in the transmission. We will either comment with the power transmission measurements or edit this alog later.
Georgia was able to get the lens translation stage software working on the wincam laptop, she will write about that separately. We were able to move the over crystal, so that is working. We need a different cable or connector for the lens with the current cable at the rack.
Camilla plugged in the QPD, the readback channels are identically 0 so we need to check if the software is running.
We made an attempt to measure the power in the seed beam at different points in the chamber to check the overall throughput. This isn't a precise measurement because we are holding the power meter by hand, but we would be able to spot anything macroscopically wrong. We did see about 10% losses this way, and decided that we need to revist the measurement when we have recently done a dither alignment of ZM2 and 3, because we have previously seen that we easily clip on the VIP with drift of those optics. It is a little concerning for the long term stability of our squeezing level, but we can hope that these optics will drfit less when the chamber is pumped down.
We also set aside the E path optics, but didn't remove them from the chamber and bag them up.
Pump fiber transmission
Today Camilla and Sheila checked the pump fiber chain, the powers are tabulated below and the transmissions below that:
The first and last measurements suggest the pump power drifted a lot during these measurements!
From the table above we calculate the transmission like in the table in alog 61375.
The two values for the total chain efficiency are using the two input power measured (2.9 vs 3.52 mW).
CLF / sqz path transmission
We started measuring powers along the CLF and sqz paths. We're seeing a loss of 8.5% somewhere in the sqz chain between ZM2 and the beam diverter (the homodyne path comes off the beam diverter which is now after ZM5).
Software for the lens translation stage
I installed the PI software on the Dell wincam laptop which is windows 7. I put the CD in and ran the install software. The instructions weren't very useful but I skipped all the stuff about updating the software, navigated to the software from program files/PI, and ran the E-870 Control program. Plugging in the driver it recognized the device straight away.
Photo of the flange side of the long in-air green pump fiber attached.