Uncertainties of static pressure measurement and dynamic pressure generation in laser interferometry-based evaluation system

• Developing a laser interferometry system for evaluating infrasound pressure sensors. • Evaluation of conversion factors for pressure measurements using laser interferometer. • Achieved < 1.4 Pa expanded uncertainty in static pressure measurement in this system. • Generation of sinusoidal dynamic pressure using bellows connected to a shaker. • Detection of millikelvin-level temperature changes with fine-sheath thermocouples. Infrasound observations are increasingly applied in various fields, including natural disaster monitoring, trajectory estimation of rockets and artificial satellites, and nuclear test surveillance. In addition to the microphones that have traditionally been used for infrasound measurements, barometric sensors capable of detecting higher-amplitude signals are now also being employed. To evaluate the dynamic characteristics of barometric sensors, we have developed a novel laser interferometry-based pressure measurement system for sensor evaluation. This system targets infrasound in the range of several tens to 1000 Pa. Compared with conventional infrasound evaluation techniques based on microphone calibration methods, it is capable of handling significantly larger pressure amplitudes. This study first investigated the linear relationship between optical path length and pressure under static conditions. The observed nonlinear component was attributed to the periodic error of the system. Based on characteristic evaluations of zero-point stability, linearity, and repeatability, the expanded uncertainty of static measurement was evaluated to be less than 1.4 Pa at 1000 Pa. Additionally, sinusoidal dynamic pressure was generated at 1 Hz by bellows connected to a shaker, and the waveform obtained by interferometry measurements was evaluated by fast Fourier transform analysis. Temperature changes with amplitudes of several tens of millikelvin associated with dynamic pressure generation were detected using the world’s smallest diameter sheath thermocouple. By employing our system, we aim to evaluate the dynamic characteristics of infrasound sensors, including amplitude and phase frequency responses.