Optical transparency is of paramount importance for visual armor and certain optical devices when subjected to severe impact conditions. Shock wave loading not only generates high pressure during hypervelocity impacts but also diminishes optical transmittance. To investigate optical transparency of transparent polycrystalline ceramic under harsh shock wave compression, this study performed experimental measurements considering the grain size effect. The findings, which pertain to polycrystalline magnesium aluminate spinel (PMAS), indicate that PMAS with nano-sized grains within the 900–1500 nm wavelength range demonstrates superior optical transparency compared to conventional PMAS with micrometer-sized grains. This result highlights the excellent optical properties of nano-grain transparent ceramics and raises hopes for their widespread application at high shock pressures.

shock compression,Nano-grain ceramic,optical properties