Note(s) This main group includes only devices, e.g. cells, the optical operation of which is modified by changing the optical properties of the medium of the device by the influence or control of physical parameters, e.g. electric fields, electric current, magnetic fields, sound or mechanical vibrations, stress or thermal effects, and it includes devices in which the electric or magnetic field component of the light beams influences the optical properties of the medium, i.e. non-linear optics, and includes the control of light by electromagnetic waves, e.g. radio waves, or by electrons or other elementary particles. [2] |