Patent ID: 8480296

Claim:
A low temperature radiometer, comprising: a main body; a main cavity disposed within the main body, the main cavity being defined through an off-axis parabolic concentrating cone formed of the inner walls of the main body, the cone having an entrance aperture and an exit aperture, the entrance aperture disposed at a first end of the main body, and a longitudinal axis of the main cavity extending from centers of the exit aperture and the entrance aperture; an exit cavity disposed within the main body, the exit cavity being defined through a cylindrical inner surface of the main body, the cylindrical surface having a longitudinal axis aligned with a longitudinal axis of the main cavity, the cylindrical surface having a first aperture in communication with the exit aperture of the main cavity, and the cylindrical surface having a second aperture disposed at a second end of the main body; a suspended thermometer suspended within the exit cavity, the suspended thermometer disposed to be in communication with radiation entering the main cavity and being diverted to the exit cavity; and an attached thermometer attached to the outer surface of the main body, the attached thermometer being in thermal communication and contact with the main body; wherein the suspended thermometer is attached to an absorptive disk suspended from conductive fibers attached to the surface of the exit cavity and to the absorptive disk.