Danny, Georgia, TVo
Turning on TCS CO2Y was difficult today for reasons unknown. CO2X is working fine as far as we know.
On July 24th 21:06:00 the CO2Y laser tripped for reasons unknown, normally when this happens it's due to a glitch in the flow sensor on the water lines and this will trip the laser controller with an error. Because we're not currently using the laser, we left it off. However, when we tried to turn it on today Georgia noticed that the sensors reading the laser power output directly from the laser head was particularly noisy even when the laser was turned off. We began to make sure the laser power supplies and interlocks were properly set for turning the laser on but it still wouldn't lase.
After consulting with Fil about the electronics, we saw that the Instek power supply on the chiller mezzanine looked like it was railing between 0 and 3 Amps, normally it should send a steady 21 amps to the laser. Also we saw that the 100V power supply that runs the PZT had a flickering LED, but Fil said that sometimes this happens and it doesn't necessarily mean something is wrong. The attached graph shows that the PZT MON was railing quite a bit and so I'm not sure if it's the power supply or the driver that's making it go crazy, investigation ongoing.
What we can try with the help of the EE guys is maybe individually swap the Instek power supply, the Kepco power supply, and possibly the laser controller in order to track down the bug. We double checked that there weren't any cables loose on the laser side on the table but everything seemed intact and the laser sees some power (4-7Watt spikes) but definitely not lasing like it normally does (steady 50W).
The first trend is a long time frame, and the second is over the course of a few hours which shows the PZT and the laser output spiking. The wiring matches E1100892 so we're still investigating.
Has the software routine that adjusts the PZT voltage for laser output power been disabled? If not, this
might be one reason why the PZT is railing.
Oh and I forgot to mention, there's the enable button on the front panel of the control chassis.
That enables some gating logic as I recall.
Thanks for the comments Peter
We enabled the gate and didn't get a response from the laser.
I think the software which moves the PZT around that you're referring to is the Guardian state which scans the PZT to find a good lock point for low frequency intensity stabilization using the PZT+chiller servo. This is usually done when the laser is already running at around 50 watts of laser output but our problem is that we can't get 50 watts to start with out of the laser.