eigenmode

An eigenmode (normal mode) of an oscillating system is a mode (here, essentially a vibration pattern) in which the whole system oscillates at the same frequency, i.e., resonating. Such a system can have more than one eigenmode, i.e., two or more frequencies of vibration encompassing vibration of the entire system. Determining such modes/frequencies can be of use in many mechanical oscillating systems, e.g., acoustics, seismic activity, etc., as well as electrical systems and quantum mechanics calculations. This can sometimes be carried out mathematically from known characteristics (Eigenmode decomposition aka eigenmode expansion, EME), which is used in simulation of optics, and in adaptive optics and back end instruments.