M. Todd, G. Vajente, L. Dartez

Thursday 12/18

1. We compared the beam profile that we fit to the modeled beam in that region, as well as what both of these beams look like at the ITM. We were initially very confused so we went back and more carefully placed the optics, taking care of the of and between the lenses in the telescope.
2. It seemed that the astigmatism was much worse than anticipated so we thought about tilting one of the lenses and seeing if we could compensate for the astigmatism. This gave us pretty confusing results, and especially because the fit to the first dataset was yielding non-physical values. For reference, the fit is done by fitting a quadratic to the beam radius squared as a function of z (i.e. w² = a+bz+cz²).
3. After deliberating in the control room, and returning to corroborate the fintrace model with jammt, we came to the conclusion that the telescope model is sensible; however, the measurement that we were taking is not descriptive enough of the beam to understand how the active telescope performs.
4. We finally decided to go in and take out the pick off to get as close of beam profile measurements to the waist of the beam after L2. We then shifted L2 5cm back toward the laser which was closer to the nominal position in the modeled layout. Here are the two plots of those beam profiles with their fits (I used a quadratic allowing M2 to vary, Gabriele has plots of minimized error of a Gaussian beam). L2 5cm further from M1 than the model. L2 close to model nominal position.