Abstract: A pair of transparent trapezoidal prisms each having angled endfaces with the larger bases in juxtaposition with respect to each other forming an interface therebetween are provided with at least one optical input and output coupled to the angled endfaces of the prisms. Optical radiation is applied to the input and normal to the angled endface at an angle greater than the critical angle with respect to the interface between the prisms. A liquid crystal beam splitter is positioned in the interface for splitting the radiation between the prisms each of which has a liquid crystal optical shutter positioned in the respective prisms to receive optical radiation which has been transmitted or reflected from the beam splitter at an angle normal to the optical shutter. Each of the shutters is provided with a variable biasing voltage of a continuous nature which is selectively variable for controlling the radiation passing therethrough thereby forming a controllable optical switch.