Patent ID: 8411712

Claim:
An apparatus comprising: an output diffractive element; a source of a plurality of substantially monochromatic light beams directed from different angles to a single location on the output diffractive element, wherein the output diffractive element spectrally combines the plurality of light beams into a single combined beam, and wherein the plurality of light beams includes a first light beam having a first central wavelength and a second light beam having a second central wavelength different than the first central wavelength; a first adjustment apparatus configured to set an adjustable characteristic of the first light beam; a second adjustment apparatus configured to set an adjustable characteristic of the second light beam; a detector configured to detect whether one of the light beams has become misadjusted, wherein the detector includes a plurality of light sensors and an imaging device that focuses the plurality of light beams onto the plurality of light sensors; a diagnoser operatively connected to receive signals from the plurality of light sensors, and configured to determine whether the first light beam is the misadjusted one and if so, to control the first adjustment apparatus to adjust the adjustable characteristic of the first light beam in order that the first light beam becomes aligned relative to the single combined beam.