Falling in to an eigenvalue-hole.

So, with Christian here and his banker suit in the closet, we whipped out the matrix-math and writers hats. He was here for the week to help push the 'demodulation' paper forward. If I had to summarize the work it would be something like this - Though typical solar spectropolarimetric systems use achromatized elements for both polarimetric accuracy and precision, there are trade-offs for night-time astronomers that make other solutions attractive. One can remove common night-time systematic effects (beam wander, guiding, ccd gain variations and cosmetics, etc) even with highly chromatic liquid crystal variable retarders and, with careful empirical calibration and a fast-switching detector system, demodulate to a stable polarimetric frame with relatively similar polarimetric sensitivity. Phew. It took two full days of screwing around with data, matrix algebra and a lot of going round in circles (daytime over coffee, night time over whiskey) to get to a point where we both had our heads wrapped around the whole thing. Glad it's done and we can just finish this paper....