Patent ID: 6314122
Filing Date: 2001-11-06
Classification: B82Y,G11B,H01S

Abstract:
Optical detection apparatus responsive to the difference in reflectivity between different objects comprisinga solid state laser including an intracavity optical waveguide in which laser radiation propagates, an output face from which a portion of said radiation emerges to form a laser output, said waveguide supporting a lasing filament that has at least two orientations within said waveguide, and at least one structural feature disposed on said output face, said feature having a reflectivity different from the surrounding regions of said output face,a controller for sequentially positioning said objects and said laser relative to one another so that said objects are proximate said feature, objects of one reflectivity causing said laser to operate in a first state in which said filament has a single, fixed one of said orientations, and objects of a different reflectivity causing said laser to operate in a second state in which said filament switches between said two orientations or is suppressed, anda sensor responsive to a parameter of said laser that is dependent on the state in which said laser is operating, thereby to sense said objects.