Self-Referenced Ambient Radiation Thermometer and Process For Determining a Temperature of a Blackbody Object

A self-referenced ambient radiation thermometer determines a temperature of a blackbody object and includes a temperature stabilized detector; a detector lens; a Lyot stop; a collimating lens; a field stop; an optical chopper such that the central radiation received by the temperature stabilized detector is modulated at a modulation frequency of the optical chopper; an objective lens in optical communication with the blackbody object and the temperature stabilized detector, optically interposed between the blackbody object and the field stop and that: receives the central radiation from the blackbody object and communicates the central radiation to the field stop; and a temperature-stabilized isothermal enclosure that provides a stable temperature and isothermal environment to elements disposed in the temperature-stabilized isothermal enclosure, wherein the elements disposed in the temperature-stabilized isothermal enclosure comprise: the temperature stabilized detector, the detector lens, the collimating lens, the Lyot stop, and the field stop.