Patent ID: 7643156

Claim:
A sensor in which measuring light is inputted and outputted therefrom as output light after physical properties thereof are changed by a specimen, and detected, the sensor comprising the following arranged from input side of the measuring light in the order listed below: a first reflector having semi-transmissive and semi-reflective properties; a translucent body; and a second reflector having perfect reflection properties, or semi-transmissive and semi-reflective properties, wherein: the first reflector and/or second reflector is brought into contact with the specimen, and the average complex refractive index thereof varies with the specimen; absorption properties for absorbing light having a particular wavelength are produced according to the average complex refractive index of the first reflector, average complex refractive index of the second reflector, and average complex refractive index and thickness of the translucent body; the properties of the measuring light are changed by the optical properties including the absorption properties, the output light is outputted from the first reflector and/or second reflector; and the physical properties of the output light that vary according to the optical properties are detected.