Method of extending the range of measurements of the energy of the secondary standard during calibration and verification of laser joulmeters

Abstract

The problem of the mismatch between the measurement ranges of the laser radiation energy of the State secondary standard of the unit of energy 2.1.ZZA.0095.2017 and the calibrated measuring instruments for low energy levels of the laser beam - joulmeters, which occurs during calibration/verification, is considered. A method is proposed for extending the measurement range of laser radiation energy of a secondary standard during calibration and verification of laser joulemeters. The extended range of laser beam energies was 1·10^–9–5·10^–1 J. The metrological traceability of measurements from joulmeters to the secondary standard was achieved by two-stage attenuation of the source radiation from the standard. The first attenuation stage is a set of neutral filters, the second is an integrating sphere. The method of extending the energy measurement range of the secondary standard consists in dividing the algorithm of its operation into two main modes: standard certification and calibration/verification of joulmeters. The main modes consist of four stages. At each stage, the secondary standard is certified and the joulemeters are calibrated/verified in one of four separate ranges overlapping in pairs in approximately the same order of laser radiation energies, collectively covering the required range. A functional diagram of an improved secondary standard of the unit of energy, which implements the proposed method, has been developed. The modes of operation of the improved secondary standard in an extended range of measured energies are considered in detail. Calculation ratios are obtained, confirming the feasibility of the method.