Patent ID: 6411374
Filing Date: 2002-06-25
Classification: G01C,G01S

Abstract:
A light-projecting/receiving unit for emitting light outside from within a transparent tube by way of a light exit position on said transparent tube, and causing a reflected part of said light from the outside to enter said transmission tube by way of a light entrance position on said transparent tube, said light-projecting/receiving unit comprising:a light source and a photodetector which are disposed so as to correspond to said light exit and light entrance positions, respectively, such that said light exit and light entrance positions are positions different from each other on said transparent tube; a light-shielding barrier provided in said transparent tube so as to separate said light exit and light entrance positions from each other; and a scanning optical system, disposed on a path of the light emitted from said light source and on a path of the light incident on said photodetector, for moving said light exit and light entrance positions, wherein both of said light source and said photodetector are disposed on one face side of said light-shielding barrier, said scanning optical system is disposed on the other face side of said light-shielding barrier, the light emitted from said light source is guided to said scanning optical system by way of an opening portion provided in said light-shielding barrier, and the light from said scanning optical system is guided to said photodetector.