Patent ID: 7843571

Claim:
A sensing system comprising: a sensing element which outputs light having a physical characteristic varying with a specimen, in response to injection of light onto the sensing element; a light injection unit which injects laser light as first light onto said sensing element, and has a wavelength stabilizing arrangement stabilizing an oscillation wavelength of the laser light by use of a wavelength selector built in the wavelength stabilizing arrangement; and a light detection unit which detects a physical characteristic of second light which is outputted from said sensing element in response to injection of said first light onto the sensing element; wherein said sensing element includes, a transparent body, a first reflector which is partially transparent and partially reflective, and is arranged on a first side of the transparent body from which said first light is injected and said second light is outputted, and a second reflector which is completely reflective, or partially transparent and partially reflective, and is arranged on a second side of the transparent body opposite to said first side; at least one of said first reflector and said second reflector is arranged in contact with the specimen, and has an average complex refractive index which varies with the specimen; and said sensing element exhibits an absorption characteristic that light injected onto the sensing element is selectively absorbed at a specific wavelength according to average complex refractive indexes which said first reflector and said second reflector respectively have and an average complex refractive index and a thickness which said transparent body has, and outputs light in which said absorption characteristic is reflected, from at least one of said first reflector and said second reflector.