This is the first interferogram processed, early in 1997. At the time these data were measured, the high speed disk mirror was not yet finished. The rotating mirror was then a 100-mm PyrexÒ flat. These data were acquired in approximately 40 ms while the disk was rotated at 720 rpm. For safety reasons, it was not spun faster because it was held in place by double-sided Scotch^TM tape.