Camilla, Miriam, Travis, Sophie
First attempt measuring the beam after a long propagation distance using the FLIR camera. Here are the measurement distances, laser power settings and corresponding images. Using the Fintrace model the beamsize at each point was modelled.
| Distance from QCL [m] | QCL power [W] | image range | Modelled Beamsize [x,y] [mm] |
| 5.732 | 0.2 | 280-284 | 7.087,7.233 |
| 8.5006 | 0.2 | 285-287 | 10.932,11.4911 |
| 15.871 | 0.2 | 288-289 | 21.219,22.868 |
| 23.618 | 0.4 | 290-291 | 32.047,34.840 |
| 32.216 | 0.6 | 292-297 | 44.069,48.129 |
note: Nominal distane to ITM is 36.735m but will be subject to exact table placement
Here is a drive with the pictures: https://drive.google.com/drive/folders/153uQSwYIMZdKYFz6KgaSdyBdOywcY-T0?usp=drive_link
A comment will be added with the procedure :)
[Sophie, Camilla, Travis, Miriam]
(This work was done yesterday, October 14, 2026)
The table layout that we used for the projections is this one. Where the distances from the QCL -> M1 -> M2 -> M3 -> M4 are the same distances as per the model that is stored in the cheta_modeling git repo.
The distances from M4 through D are not part of the original CHETA table setup and they were just used and labeled like that for the projections we were doing. The distances in between these mirrors is detailed in the image itself.
Now, before starting the projections we aligned the green laser to the irises on the table, this is to make sure the the green laser is co-aligned with the QCL CHETA laser. We started by projecting the green laser a short distance outside of the table onto a laser barrier to see where it landed, then turned the green laser flipper down to then project the CHETA laser (onto the same barrier) and checked they landed both as close to each other as possible. We moved the laser barrier back several times, each time checking where our green laser landed first. To see the CHETA beam we were using a FLIR camera (EXTECH i5). You can see our amazing pictures (taken at different distances) in the Google folder Sophie shared in this alog.
Camilla was pointing the FLIR camera to the beam (which was hitting the laser barrier) and I was holding a metal ruler which had very skinny pieces of tape taped every centimeter (I was warming up the ruler with my hands in between measurments), the ruler was hold either below or on top of the beam to gauge the beam size at the specific distances we were measuring it at. In this picture, you can see Camilla with the FLIR camera and me with the ruler, artistically framed by Sophie. Sophie was out laser operator. The QCL CHETA laser was always started at minimum power (0.5 A) and then slowly brought to full power until we could see the beam on the barrier/FLIR camera.
We use the minimum QCL power possible to still be able to see the beam, which meant we were chaging the power of the QCL with the rotaiton stage as we were moving away from the table. For the specific power that we used, see Sophie's table above.
We note that tha the laser barrier was flimsy and therefore it was challenging to keep the fabric straight while taking our pictures. Today we will go back to do more projectes and we will use a slightly less flimsy barrier to project the laser into.
This was done for CHETA Y, along the Y-arm inside the LVEA.