Comparison reference etalon of unit laser radiation power

An etalon was developed for comparing national secondary and governmental primary standards of laser radiation power. It contains, in addition to two reference instrument transducers operating by different principles and having different spectral characteristics, a laser source emitting at the 0.63 micron wavelength with high power stability, a recording instrument, a calibrating instrument, and signal shaping-checking circuits. The first reference transducer is a nonselective calorimetric one, a model of a black body consisting of two parallel conical copper shells with a 15 deg taper inserted one inside the other with two thin-film equivalent resistors between them. The second reference transducer is a precise photothermoelectric one for comparison of standard with similar spectral and space distributions of the radiation power, also for checking the performance of the calorimetric reference transducer. It consists of a photoelectric cell and a thermoelectric cell in thermal contact with one another through an integrating sphere on which they are placed not far apart. An auxiliary photodiode is provided for checking the radiation power level after it has stabilized. The instability of this etalon does not exceed 0.5 x 10 to the -4th power during 1 hour.