Research On A Portable High Precision Optical Power Meter Based On Electrical Substitution Principle

As a precise optical power measuring instrument,optical power meter is widely used in optical communication,laser processing,biomedicine,modern national defense and optical fiber sensing.Due to the strict requirements for the spectral range and power of the required laser in various production and application fields,the optical power meter must have the ability to accurately measure the optical power in different spectral ranges.However,the measurement accuracy of the existing portable optical power meter is difficult to exceed 1%.Therefore,the development of high-precision,portable,simple operation and suitable for a variety of working scenes is one of the important development directions of optical power meter.In this paper,according to the highprecision application requirements of optical power meter,a portable high-precision optical power meter based on the principle of electric substitution is developed,the measurement model and thermoelectric model of optical power meter are established,the key technology research and simulation analysis of optical power meter are carried out,and the performance test and uncertainty evaluation of optical power meter are carried out.The research and analysis results show that the power meter can realize the precise measurement of optical power in the spectral range of 400nm-20 um and the power range of 1mw-100 mw,and the relative expanded uncertainty can reach 0.82%when the measured optical power value is 10 m W.Firstly,the measurement principle of optical power meter based on electric substitution principle is introduced,and the measurement model of optical power meter is established.This paper briefly introduces the structure and composition of optical power meter,analyzes the basic design requirements of optical power meter,and summarizes the key technology of optical power meter development;The heat conduction structure and characteristics of the optical power meter are studied,the three-dimensional heat conduction model of the heat conduction structure is simplified,the heat conduction differential equation is solved,and then the time constant and response calculation model characterizing the thermal performance of the optical power meter are obtained.The calculation formula of optical power measurement uncertainty is deduced,the influencing factors of optical power measurement are analyzed,and the uncertainty of optical power meter is roughly distributed according to the uncertainty better than 1%.Secondly,the core devices of optical power meter are designed in detail,the key technologies of optical power meter are studied,and the simulation model is established for simulation analysis.Study the core component of optical power meter absorber,analyze the material characteristics of absorption substrate and absorption layer,and design the structure of absorption substrate;At the same time,the composite paraboloid reflector is applied to the absorber to improve its absorption rate,and the absorption rate of the absorber is increased to more than 0.99734.The mathematical model of composite paraboloid reflector is established,the reflector structure is designed and optimized,the reflection efficiency is simulated and analyzed based on Monte Carlo method,the absorption measurement experiment is built,and the absorption of optical power meter absorber is measured.The relative standard uncertainty of absorption measurement is 0.0012%.The temperature measurement system,electric heating control system and heat conduction structure of the optical power meter are designed.The heat transfer characteristics of the optical power meter are studied by finite element method.The effects of photoelectric heat transfer inequivalence,the position and size of incident light spot and ambient temperature on the measurement uncertainty of the optical power meter are quantitatively analyzed.Finally,the performance test and analysis evaluation of the optical power meter are carried out to evaluate the absolute measurement accuracy of the optical power meter,and the effectiveness of the uncertainty evaluation results is verified by direct comparison.Carry out the test experiments of time constant,sensitivity and repeatability of optical power measurement of optical power meter,and evaluate the class A and class B standard uncertainty of optical power meter.According to the “JJF1059.1-2012 Evaluation and Representation of Measurement Uncertainty”,Combining the class a standard uncertainty and class B standard uncertainty of optical power meter,the relative expanded uncertainty of optical power meter is 0.82%(k = 2).According to the “JJF1117-2010 Metrological Comparison”,through direct comparison with the standard detector,the normalized deviation En=0.46<1,which verifies the effectiveness of the accuracy evaluation results of the portable self-calibration optical power meter based on the principle of electrical substitution.