Optical relay using variable birefringence element - has electric field applied parallel to direction of light propagation to control birefringence of prism.

摘要

The optical relay employs an element with a variable birefringence controlled by the electrical field parallel to the light propagation direction. This element has a transparent conductive layer on one face and a dielectric mirror and electrodes on the opposite face, cooperating with further electrical and/or optical system to provide an electrical field across the element. The birefringence generated within the element is detected via a linearly polarised light source at the focus of a lens directing a parallel light beam onto the mirror. The focal plane of this lens includes a screen for shielding the images of the light source due to parasitic reflection from the faces of the element. The element is in the form of a prism block with a wedge angle of between 1 and 4 degrees.