Camilla C., TJ

Recently, the CO2Y laser that we replaced on Oct 22 has been struggling to stay locked for long periods of time (alog81271 and trend from today). We've found some loose or bad cables in the past that have caused us issues, so we went out on table today to double check they are all ok.

The RF cables that lead into the side of the laser can slightly impact the output power when wiggled, in particular the ones with a BNC connector, but not to the point that we think it would be causing issues. The only cable that we found loose was for the PZT that goes to the head of the laser. The male portion of the SMA that comes out of the laser head was loose, and cannot be tightened from outside of the laser. We verified that the connection from this to the cable were good, but wiggling it did still introduce glitched in the PZT channel. I don't think that we've conviced ourselves that this is a problem though, because the PZT doesn't seem to glitch when the laser loses lock and instead it will run away.

An unfortunate consequence of the cable wiggling was that one of the Beckhoff plugs at the feedthrough must have been unseated slightly and caused our mask flipper read backs to read incorrectly. The screws for this plug were not working so we just pushed the plug back in to fully seat it and all seemed to work again.

We still are not sure why we've been having these lock losses lately, the 2nd and 3rd attachments show a few of them from the last day or so. They remind me of back in 2019 when we saw this - example1, example2. The fix ultimately a chiller swap (alog54980), but the flow and water temp seem more stable this time around. Not completely ruling it out yet though.