METHOD FOR MEASURING ABSOLUTE REFLECTANCE BY DOUBLE LIGHT REFLECTION

摘要

PROBLEM TO BE SOLVED: To provide a measuring method, for an absolute reflectance, in which an opaque object is used as an object and whose sensitivity and accuracy are high. SOLUTION: A sample temperature riseΔTac (1) due to only the output light 12 of a light-output laser with reference to a flat boardlike sample 17 as an opaque body is measured. A temperature riseΔTac (2) at the sample 17 due to the output light 12 and due to the re-incidence on the sample of its reflected light 12a measured. The relative reflectance R of the sample 17 is found by R=[ΔTac (2)-ΔTac (1)/ΔTac (1)]. The re-incidence on the sample 17 of the reflected light 12a is performed by using a concave mirror 20 before which a shutter 19 is installed.