https://www.selleckchem.com/ While optical aberrations caused by atmospheric turbulence have been extensively investigated and well characterized, recent research has identified structural differences in optical phase distortions caused by aircraft-induced, compressible turbulence. These so-called aero-optical distortions can be a critical obstacle in the development of airborne optical systems and reduce the fidelity and on-target intensity of optical beams. Using a model index-of-refraction spectrum that accounts for changes in density due to both temperature and pressure fluctuations in aero-optically active flow fields, expressions for the two-dimensional phase distortion over an aperture are developed. From these results, relations among $\rm OPD_\rm rms$, turbulent flow scales, and aperture size are examined while accounting for the effects of piston and tip/tilt corrections. Additionally, using the model spectrum, resolution requirements for wavefront sensors and numerical simulations of aero-optical flows are examined.Optical diagnostics of gas-phase pressure are relatively unusual. In this work, we demonstrate a novel, rapid, and robust method to use laser-induced grating scattering (LIGS) to derive this property in real time. Previous pressure measurements with LIGS have employed a signal fitting method, but this is relatively time-consuming and requires specialist understanding. In this paper, we directly measure a decay lifetime from a LIGS signal and then employ a calibration surface constructed using a physics-based model to convert this value to pressure. This method was applied to an optically accessible single-cylinder internal combustion engine, yielding an accuracy of better than 10% at all tested conditions above atmospheric pressure. This new approach complements the existing strength of LIGS in precisely and accurately deriving temperature with a simple analysis method, by adding pressure information with a similarly simple method.A single-shot