SENSOR APPARATUS

PROBLEM TO BE SOLVED: To provide a technique of a desired sensor apparatus using a total reflection optical system capable of utilizing evanescent waves to obtain high resolution because a sensor apparatus using terahertz waves is difficult to obtain high resolution when using a spatial coupling system.SOLUTION: The sensor apparatus includes: an optical waveguide including an electro-optic crystal 1 for propagating light; a coupler 3 arranged adjacently to the optical waveguide to propagate a terahertz wave generated from the electro-optic crystal by propagating light through the optical waveguide; and a detector 7 for detecting the terahertz wave propagated through the coupler or the light propagated through the optical waveguide. The terahertz wave is totally reflected on a portion of the coupler, which is opposed to a portion adjacent to the optical waveguide, and is propagated through the optical waveguide, and on the total reflection part, the terahertz wave causes to interact with a test object 6 arranged on the total reflection part.