Quantification of aero-optical phase distortion using the small-aperture beam technique

We discuss the small-aperture beam technique, a new way of experimentally quantifying the instantaneous optical wave front distortions imposed by propagation through an optically active, turbulent flowfield. We lay out the theoretical basis for the technique and the relationship of the measured jitter of a small-aperture probe beam to optical path difference. A numerical simulation of a two-dimensional heated jet is used to explore the validity of using beam-jitter signals from multiple probe beams to obtain optical path difference in a flow region where eddy production constitutes the major character of the turbulent flowfield.

[1]  Dietrich W. Bechert,et al.  Self-excited oscillations and mixing in a heated round jet , 1990, Journal of Fluid Mechanics.

[2]  George Havener,et al.  Aero-optics testing capabilities at AEDC , 1992 .

[3]  C. R. Truman,et al.  Prediction of optical phase degradation using a turbulent transport equation for the variance of index-of-refraction fluctuations , 1990 .

[4]  G. Choksi,et al.  Numerical Simulation of the Unsteady Wake Behind an Airfoil , 1989 .

[5]  Robert K. Tyson.  Chapter 1 – History and Background , 1991 .

[6]  Turbulent-fluid-induced optical wavefront dynamics - Near- and far-field implications , 1994 .

[7]  P. Monkewitz,et al.  Oscillations in the near field of a heated two-dimensional jet , 1993, Journal of Fluid Mechanics.

[8]  H. A. Stine,et al.  Light Diffusion Through High-speed Turbulent Boundary Layers , 1956 .

[9]  W. J. Steinmetz.  Second moments of optical degradation due to a thin turbulent layer , 1980 .

[10]  G W Sutton,et al.  Beam-jitter measurements of turbulent aero-optical path differences. , 1992, Applied optics.

[11]  Robert K. Tyson.  Principles of Adaptive Optics , 1991 .

[12]  C. Hogge,et al.  Characteristics of phase-aberrated nondiffraction-limited laser beams. , 1974, Applied optics.

[13]  John B. Wissler,et al.  Transmission of thin light beams through turbulent mixing layers , 1992 .

[14]  H. Booker,et al.  A Theory of Radio Scattering in the Troposphere , 1950, Proceedings of the IRE.

[15]  E. Acton.  A modelling of large eddies in an axisymmetric jet , 1980, Journal of Fluid Mechanics.

[16]  Ronald J. Hugo,et al.  Experimental measurement of a time-varying optical path difference using the small-aperture beam technique , 1993, Optics & Photonics.

[17]  Walter H. Christiansen,et al.  Coherent structure effects on the optical performance of plane shear layers , 1991 .

[18]  F. O. Thomas.  Structure of Mixing Layers and Jets , 1991 .

[19]  George W. Sutton,et al.  Effect of turbulent fluctuations in an optically active fluid medium. , 1969 .

[20]  C. Randall Truman,et al.  Effects of organized turbulence structures on the phase distortion in a coherent optical beam propagating through a turbulent shear flow , 1990 .