High-precision measurement of refractive index in explosive-driven air blast waves for density and pressure determination

Air refractive index alteration is an important research technique used to examine blast density and pressure. However, precise time-course measurements of refractive index changes at a fixed point caused by air blast waves are challenging due to the necessity for high precision and noise immunity. This study proposes a dual-probe, dual-frequency fiber-optic displacement interferometer that achieves nanometer-level accuracy and can tolerate light intensity fluctuations and transmission-fiber interference. The specially designed sensor enables the measurement of refractive index at a fixed point resulting from explosive-driven air blast waves, further allowing for obtaining the pressure and density information.