In a device for switching a light beam, the conditions of propagation of the beam are modified locally under electric control by interposing on the beam path a fluid which modifies the conditions of refraction of the medium traversed by the beam....http://www.google.se/patents/US4818052?utm_source=gb-gplus-sharePatent US4818052 - Device for optical switching by fluid displacement and a device for the composition of a line of points
