US Patent 10423222 Holographic waveguide optical tracker

There is provided an object tracker having: a first waveguide; a source of illumination light; a detector optically coupled to the waveguide; and at least one grating lamina formed within the waveguide. Illumination light propagating along a first optical path from the source to an object in relative motion to the object tracker. Image light reflected from at least one surface of an object is deflected by the grating lamina into a second optical path towards the detector.