Fresnel-reflection-based light pickoff element for laser-based systems

Abstract

A laser projection system is provided that includes at least one pickoff element or pickoff interface that redirects a portion of input laser light toward one or more photodetectors for purposes such as laser output power monitoring. An interface of a given pickoff element or a given pickoff interface uses Fresnel reflection to redirect the input laser light. The Fresnel reflection occurs due to a difference in indices of refraction between two materials that meet to form that interface. In some embodiments, a pickoff element is disposed in an optical path between a beam combiner and an optical scanner of the system. The pickoff element can be a plate beamsplitter, a cube beamsplitter, or a prism. In some embodiments, at least one pickoff interface is provided between two or more substrates of the beam combiner, the substrates that form a given pickoff interface having different respective indices of refraction.