Friday, June 29, 2012

Day 33, 6/29/2012 -- More scans, more paint

Today Jeff and I set up the Ebert-Fastie to do scans to map the phase response of the EBEX achromatic HWP. Unlike regular single plate HWPs, which are tuned to a specific frequency and its multiples, the EBEX AHWP is a stack of 5 birefringent plates oriented in such a way as to increase their bandwidth. The penalty for this is that the so-called 'phase response' is no longer a simple function -- for a given input polarization angle, the output polarization angle varies slightly as a function of frequency. We need to know this effect in order to properly analyze our data, and so by putting a polarizing grid at the output of the Ebert-Fastie and rotating the HWP, we can map the phase response of the HWP to polarized light as a function of frequency. After a few fits and starts, we managed to get the scans going by the early afternoon and have three full scans in the can with more to come tomorrow.

On the gondola side, Michele managed to get the elevation actuator completely disassembled and proceeded to degrease the various parts in the ultrasonic cleaner. Britt, Andrei, and KyleH started the process of painting various gondola bits that weren't powdercoated, and Chappy, Joy, and Seth continued their software work which results in an impressive amount of clacking on keyboards but doesn't make for very interesting blog posts.

Kate and Kyle left today; Kyle will be returning next week after a short break from Texas.


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