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September 2016, 17 (Saturday)
- Finish mounting NIKA2 back in place. Everything went fine and smoothly, without problem.
- Start leak tests.
- Zemax simulations done. Ray tracing figures look scary, but it's the PSF that matters:
For the default on the 1K lens: ~1/3 of the image surface is affected (top side); extra aberrations appear in the side lobes at ~10^-2 level, the beam peak decreases by up to 6%, the encircled energy at the 1st dark ring (13dB level) decreases by up to 5% <=> the benefice of the corrugations AR effect is cancelled out for those pixels. It seems acceptable; we'll see on the sky with beam maps.
For the default on the 2 100mK lenses: 80% of the image is affected (red cross shape); extra aberrations appear in the side lobes at ~5x10^-3 level, the beam peak decreases by up to 4.5%, the encircled energy at the 1st dark ring (~-13dB level) decreases by ~3.7% <=> a significant fraction of the benefice of the corrugations AR effect is cancelled out, but not all. It seems acceptable.
September 2016, 16 (Friday)
- Arrival at the telescope of Samuel.
- Unload truck dismount NIKA2 nose, roll NIKA2 body it in the corridor.
- Dismount NIKA2 body, up to the cold stage optics.
- Change the 1K lens in the corridor: remove the smooth one, place the corrugated one. See a small default that hadn't been seen before on a section of the new corrugated lens: groove ~5mm wide, ~0.1-0.3mm deep, ~5-7cm long. Probably acceptable; decide to keep the lens, Samuel will simulate the effect with Zemax.
- Change the 100mK lenses in the servo room (floor below the receiver cabin). Here also a small known default on 2 of the 5 lenses: ridge ~0.5mm wide, ~0.3mm high, along 2 perpendicular diameters. Before coming Samuel estimated with a simplified simulation it was acceptable, he will simulate more accurately the default.
- Change the 2mm array: replace the 1020 KIDs array with the new 616 KIDs array.
- Change the dichroic.
- Start mounting again everything together.
September 2016, 15 (Thursday)
- Arrival at the telescope of Johannes, then Alessandro, Martino and Aurelien with the truck.