Patent ID: 6992828
Filing Date: 2006-01-31
Classification: G02B

Abstract:
1. An optical attenuation system comprising a diffusing unit ( 14 , 15 , 16 , 17 ) for receiving and diffusing an input light beam diverging at a divergence angle (θ) from a source ( 10 ) and a detection unit ( 11 , 18 , 19 ) adapted to receive a desired portion only of the light diffused by said diffusing unit ( 14 , 15 , 16 , 17 ), said diffusing unit ( 14 , 15 , 16 , 17 ) comprising a plurality of diffusing elements including a first diffusing element ( 14 ) for receiving and diffusing said input light to provide a distributed light source for a subsequent one ( 15 ) of said diffusing elements, and a final one ( 17 ) of said diffusing elements for supplying diffused light to said detection unit ( 11 , 18 , 19 ), the arrangement being such that the light detected by said detection unit ( 11 , 18 , 19 ) is substantially independent of variations in said divergence angle (θ) of the input light beam.