An embodiment of a light homogenizing apparatus having one or more emitters (110, 120) incident on a light mixing element. The emitters including at least one laser light source. The light mixing element comprising a diffuser (130) followed by an internally reflective light guide (160). This apparatus substantially homogenizes light from all emitters (110, 120) before light exits the internally reflective light guide (160) where it could then be incident on living tissue for use in photoplethysmographic measurement. Other embodiments are described and shown.
