Disclosed herein is a sensor utilizing attenuated total reflection. The
sensor is equipped with a prism, a metal film formed on a surface of the
prism, an optical system for making a light beam enter the prism at
various angles of incidence so that the condition for total internal
reflection is obtained at the interface between the prism and the metal
film, and photodetectors for detecting the light beam satisfying total
internal reflection at the interface. In the sensor, a super luminescent
diode is employed as a light source that emits the light beam.
