Dynamically aligned interferometer

Figure 5.10. Path of three parallel laser beams through a dynamically aligned Michelson interferometer. The beams are detected by three separate detectors, and the signals from the detector are fed to three actuators that control the alignment of one of the minors. (Reproduced from [5], by permission of John Wiley Sons, Ltd. copyright 2002.)...

In both the continuous-scan and step-scan spectrometers, the extremely precise positioning of the movable mirror is ensured by adopting an efficient feedback mechanism such as the above-mentioned dynamic alignment. Further, some spectrometers are constructed so as to isolate the interferometer base from shocks, including earthquakes. It should be kept in mind that, even if such spectrometers are in use, shocks, vibrations, and tilts given inadvertently to the spectrometer may still have an adverse effect on the results of measurements. 

J. M. Coffin, Interferometer of an infrared spectrometer with dynamic moving mirror alignment, U.S. patent 5,883,712 (assigned to Nicolet Instrument Corporation, Madison, WI, March 16, 1999). 

---