Thermal cameras installation

Today we tried to install the thermal cameras for the TCS beam monitoring. The cameras should be installed on the beam reflected by the beamsplitter that recombines the CH with the annular heating. The whol;e setup was simulated with Zemax and according to the simulation the suitable optics have been purchased. We started from the WI.

We immediately realized that the sizes of the optics are at the limit of the size of the beam. Moreover the that area of the bench is really crowded and this makes it difficult to position the optics properly.

Anyway, we managed to get the beam onto the camera, which is working properly as well as the software. The attached figure shows how the beam is seen by the camera.

We learn a few things looking at it:
1) the fringes on the image are probably due to the interference between the reflections from the surfaces of the beam splitter, this as already been observed in low reflectivity beam splitters.
2) the loss of power in the upper part of the figure is likely due to clipping from the mirror that is sending the beam onto the camera.
3) the loss of power in the upper-left corner of the image it probably due to clipping of the first lens of the imaging system, which is the most critical from the point of view of the size.

We decided to keep the optics in place (they do not modify in any way the TCS telescope), but to remove the camera and put a beam dump. further considerations are needed before trying to install the cameras again.

I attach 2 figures, the difference is only the gain of the camera.