The A/D converter produces a continuous stream of matching interferogram points for both the laser and infrared channels. Some reduction of modulated amplitude can be seen where the laser frequency is highest. Part of the amplitude reduction is caused by cable capacitance loading the preamp. There may be some contribution from the mirror distortion, but these two effects are difficult to separate. These scans are each 3 milliseconds long, corresponding to 10,000 rpm. These scans are then separated, for further processing, into segments at the points where the optical velocity drops to zero.