Proc. of SPIE Vol. 7013 70130D-1 - The UC Berkeley Infrared ...

Figure 5: An interference fringe signal of Orionis under exceptionally good seeing conditions.Atmospheric fluctuations are small enough that only very weak sidebands over a small fraction ofone Hertz are produced by their variations. The Data were taken for 512 seconds, and the verynarrow resulting fringe has a width due primarily to this finite time of measurement 3Figure 6: An interference fringe from Orionis under very poor seeing conditions. In this casethe atmospheric pathlength is fluctuating severely and on timescales comparable with the inversewidth seen, or about 1/15 sec. This is fast for wavelengths as long as 11 μm. In spite of suchfluctuations, the fringe magnitude, or total power, can be rather accurately determined byintegrating the total power under the curve of this figure 3 .Proc. of SPIE Vol. 7013 70130D-12