| 摘要 |
Apparatus for extracting light from an optical waveguide ( 12 ) by bending the waveguide to such an extent that a portion of any light propagating in the waveguide leaks therefrom comprises a bending unit ( 10 ) for bending a portion of the waveguide in dependence upon a control signal (S) and providing a detection signal (P<SUB>a</SUB>) proportional to light leaked from the waveguide. A control unit ( 14 ) varies the control signal (S) in response to the detection signal (P<SUB>a</SUB>) to cause the bending unit ( 10 ) to progressively decrease the bending angle and has a processor unit ( 46 ) which computes a rate of change (dP<SUB>a</SUB>/dR) of the detection signal (P<SUB>a</SUB>) with respect to bending radius (R) and causes the bending unit to maintain that bending radius at which the aforesaid rate of change is substantially equal to a predetermined value.
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