This document is a review of my research work in optical metrology to probe high enthalpy hypersonic flows encountered during atmospheric reentry. I first relate the critical issues of atmospheric reentry which must be well understood and mastered for safe return of human flight from space or successful planetary probing and sample return. I then describe different measurement techniques to characterize gas flows around reentry vehicles in test in ground facilities or in flight. Particularly, linear optical methods like Electron Beam Fluorescence (EBF), laser induced fluorescence, laser absorption spectroscopy (TDLAS), emission spectroscopy and Rayleigh Lidar.
