An optical beam combiner for combining a plurality of light beams comprises: a plurality of spherical mirrors; and a flat mirror, the plurality of spherical mirrors and the flat mirror configured to form at least one multiple pass light beam optical arrangement for receiving the plurality of light beams...http://www.google.com.au/patents/US20060034567?utm_source=gb-gplus-sharePatent US20060034567 - Optical beam combiner
