[Thomas Greg Gerardo Arnaud]

Today we finished setting back the optical lever at ETMx, all went well, we just need to check for digital comp filters.

• Removed the receiver box from the pylon (this was tricky since we couldn't remove one of the screws. We had to torque it until breakage to be able to remove the plate. The thread was cut and polished, but is still in the pylon)
• Elevated the pylon by a few inches
• Swapped the mounting plate with a one adapted to the new level, mounted it on the pylon
• Mounted the two motorized translational stages on the plate , with the photodiode circuit board
• Centered the pd on the main reflected laser beam by changing the position of the motorized stages
• Plugged the pd to the whitening chassis, verified the signals for the 4 quadrants (we had to turn the analog switch gain from the circuit board to get a signal of ~thousands counts/quadrant)
• Took a spectra comparing with a reference from april (cf attached screenshot). High frequencies differ, probably because of bad digital whitening compensation filters, otherwise the signal looks healthy