OPTICAL MEASURING METHOD AND OPTICAL MEASURING APPARATUS

摘要

PURPOSE:To measure the quantity of reflected light reflected by the measuring object and made possible measurement of the refractive index and other optical characteristics of the measuring object from the quantity of reflected light by using a branching coupler constituted by optical fibers. CONSTITUTION:The light of a light source 11 passes through an optical fiber 12 and is divided to two in a branching coupler 13. One is led into measuring liquid 14 for refractive index via fiber 12' and the other into a photo detector 15 via fiber 12''. Now, with the refractive index of the core of the fiber 12' being let to be (nc) and the refractive index of liquid of an unknown refractive index to be (nx), the light is reflected at the boundary of the core of the fiber 12' and the liquid 14 and arrives at the coupler 13 through the fiber 12', from where it is branched and goes backward. This light then goes through the fiber 12''' and reaches a detector 16, whose output is processed together with the output of the detector 15 in an amplifying operator 17, thence in a meter 18 the refractive index (nx) related to quantity of reflection R by the nx = (1 - R<1/2>)nc/(1 + R<1/2>) formula is displayed. Various optical characteristics of the measuring object may be rapidly and readily measured by using the simple optical branching coupler.