Thus far, the software needed for the Magewell video encoder has been successfully installed on Donatella. OBS studio has also been installed and works correctly. OBS will be the video recording software that can be interfaced via command line once the SDI video encoder starts working. (https://github.com/muesli/obs-cli)
So far, the camera can not be connected to the Magewell encoder. The encoder continues to have a pulsing error light that indicates "no signal" or "signal not locked". I have begun testing on a secondary camera, directly connected to the Magewell encoder with similar errors. This may be able to be resolved once more information about the camera and its specifications/resolution is uncovered. At this time I have not found any details on the LCL-902K by Watec that was given to me by Koji. I will begin looking into the model used in the 40 meter next.
During my time shadowing Anchal, we discussed the need for digital control systems on the suspension systems for the 40 meter optics. The controls and diagnostics system (CDS) allows us to develop our own feedback controls and filters for the suspension systems by taking in analog signals from the shadow sensors. The feedback control system developed in the CDS then utilizes the OSEM actuators to dampen harmonic motion and noise on the suspension lines. While improving these feedback loops is an ongoing challenge, it is a problem that is likely non-linear, meaning the system must be understood on a much higher level to make further improvements. This brings us to the new addition of a wavefront sensor in the 40m lab, which will allow for constant monitoring of the active wavefront in the interferometer. The wavefront will soon be used for gathering training data for a neural net that will help further analyze the non-linear effects within the suspension and damping system. What Anchal was working on today was an update within a CDS model for clioo to allow for the integration of the wavefront sensor such that he may use a switch to change between connections in the mode cleaner and the arm cavity. The CDS models may be edited and updated using Matlab/Simulink to arrange blocks and code in a robust and visual manner. The final system designed in Simulink can then be saved and compiled using the real-time code generator (RCG), which cross-compiles the Simulink file into C code that can be read by the CDS system to assign inputs, outputs, and various logic or algorithms for filtering.
In nodus, I moved the elog from /export to /cvs/cds/caltech. So now it is in the cvs path instead of a local directory on nodus.
For a while, I'll leave a copy of the old directory containing the logbook subdirectory where it was. If everything works fine, I'll delete that.
I also updated the reboot instructions in the wiki. some of it also is now in the SVN.
Today we met and we finally come up with a lot of cool, clever, brilliant, outstanding ideas to organize the lab.
You can find them on the Wiki page created for the occasion.
we hung two new WALL cable racks. One is on the pillar next to the Sp table, the other is next to the PSL computer rack.
To do that we had to drill holes in the wall since the simple screws weren't strong enough to keep them up.
One of the racks, the yellow, is dedicated to 4-pin lemos and other thick cables.
This afternoon the elog crashed. We just restarted it.
This afternoon we tried to improve the mode matching of the beam to the PMC. To do that we tuned the positions of the two lenses on the PSL table that come before the PMC.
We moved the first lens back an forth the without noticing any improvement on the PMC transmitted and reflected power. Then we moved the first backwards by about one cm (the order is set according to how the beam propagates). That made the things worse so we moved also the second lens in the same direction so that the distance in between the two didn't change significantly. After that, and some more adjustments on the steering mirrors all we could gain was about 0.2V on the PMC transmission.
We suspect that after the problems with the laser chiller of two months ago, the beam size changed and so the mode matching optics is not adequate anymore.
We have to replace the mode matching lenses with other ones.
This morning I found all the watchdogs had tripped during the night.
I restored them all.
I can't damp ITMX. I noticed that its driving matrix is all 1s and -1s as the the right values had been lost in some previous burtrestoring.
Rana fixed the problem. He found that the side damping was saturating. He lowered the gain a little for a while, waited for the the damping to slow down the optic and then he brought the gain back where it was.
He also upadted the MEDM screen snapshot.
The mode profile of the new input optics was measured.
Although the distance between each optic was not exactly the same as the design because of narrow space,
we measured the profile after the curved mirror (MMT1) that Jenne and Kevin put in the last week.
(interference from MMT1)
Below is a sketch of the current optical path inside of the chamber.
In the beginning of this measurement, the angle between the incident and the reflection on MMT1 (denoted as theta on the sketch) was relatively big (~40deg) although MMT1 was actually made for 0deg incident.
At that time we found a spatially large interference imposed on the Gaussian beam at the beam scan. This is not good for mode measurement
This bad interference can be caused by an extra reflection from the back surface of MMT1 because the interference completely vanished by removing MMT1 .
In order to reduce the interference we decreased the angle theta as small as possible. Actually we made it less than 10deg which was our best due to narrow space.
Now the interference got less and the spot looks better.
The picture below shows an example of the beam shape taken by using the beam scan.
Top panel represents the horizontal mode and bottom panel represents the vertical mode.
You can see some bumps caused by the interference on the horizontal mode, these bumps may lead to overestimation of the horizontal spot size .
The above plot shows the result of the mode measurement.
Here are the parameter obtained by fitting. The data is also attached as attachment:4
For the record, we wanted to check whether the fringes on the beam spot were caused by SM2 (see diagram above). We tried two different mirrors for SM2,
The first was one of the flat, 45 degree ones that were already on the BS table. The last, which is the one currently in place, was inside the plastic box with the clean optics that Jenne left us .
The fringes were present in both cases.
Today the new Dell computer for the GSCS (General SURF Computing Side) arrived.
We put it together and hooked it up to a monitor. And guess what? It works!
I'm totally impressed by how the Windows get blurred on Windows 7 when you move them around. Good job Microsoft! Totally worth 5 years of R&D.
It has rained continuously for the last 24 hours. Bob walked through the lab looking for possible water infiltrations. The floor looked dry: no puddles or leaks anywhere so far.