Abstract: A modulated light source (31) transmits light pulses through an optical channel (20) to an optical sensor (10) remotely located from the cockpit and mounted proximate an aerodynamic surface (14) of an aircraft. In the absence of ice a baseline amount of light is returned inward via the optical channel. When water, ice, or de-icing fluid covers the light sensor, a detectable variable amount of light pulses are returned by the sensor inward through the optical channel, and are detected by a light detector (34) which generates an electrical output signal that varies as a function of the type, amount, and rate of substance accretion. The output signal is visually displayed (37) and the pilot may also be audibly warned.

Abstract: A modulated light source (31) transmits light pulses via a prism (27) through a monofilament optical fiber light channel (20) to an optical sensor (10) remotely located and flush mounted to an aerodynamic surface (14) of the aircraft most likely to accrete ice. In the absence of ice little to no light is reflected inward via the light channel. When water, ice, or de-icing fluid covers the light sensor, an increased amount of light pulses are reflected inward through the single fiber optic light channel and prism assembly where they are detected by a light detector (34) which generates an electrical output signal indicative of the type, amount, and rate of ice accretion. The output signal is visually displayed (37) and the pilot may be audibly warned.