Patent ID: 7251038

Claim:
An apparatus for processing signals from a remote optic sensor, said apparatus including means for supplying a broad band light beam for use in interrogating the optic sensor, said apparatus comprising: a first narrow band filter and a second narrow band filter, said first and second narrow band filters having respective centre frequencies spaced about the desired centre frequency of the broad band light source; coupling means for coupling a first sample of said broad band light beam through said first narrow band filter and a second sample of said broad band light beam through said second narrow band filter; first means to measure the filtered first sample of said broad band light beam; second means to measure the filtered second sample of said broad band light beam; comparison means to compare the outputs of said first means and said second means and to produce an error indication in response thereto; and means to employ said error indication to apply a correction to said means to produce said broad band light beam to move the central frequency of said broad band light beam towards said desired centre frequency.