Balancing radiometer

A balancing radiometer for measuring the intensity of a source of electromagnetic radiation comprising:

• a. a pair of substantially identical electromagnetic radiation sensors, each of said sensors including:
• i. a thermally conductive substrate, at least one surface of said substrate being comprised of an electrically insulating material, said at least one surface being disposable in confronting relation with said radiation source;
• and
• ii. means disposed on said at least one surface of said substrate for resisting the flow of electric current and absorbing incident radiation;
• b. means for shielding one of said pair of sensors from said radiation source, the other of said sensors being unshielded;
• c. first means disposed in thermal conducting relation with the substrate of said shielded sensor for providing a first signal proportional to the temperature of said shielded sensor;
• d. second means disposed in thermal conducting relation with the substrate of said unshielded sensor for providing a second signal proportional to the temperature of said unshielded sensor;
• e. means for comparing said first and second signals;
• f. variable power supply means responsive to said signal comparing means;
• g. means for connecting said power supply means to said electric current flow resisting means for heating said shielded sensor to a temperature equal to the temperature of said unshielded sensor whereby to equalize said first and said second signals;
• and
• h. means for measuring the power output of said power supply means.