Sensing Refractive Turbulence Profiles Using Wave Front Slope Measurements fromTwo Reference Sources

摘要

This thesis examines a remote sensing technique for measuring the atmosphericstructure constant as a function of altitude by performing spatial correlation or wavefront sensor measurements. Two point sources are used to irradiate two wavefront sensors in the aperture plane of an optical system. The geometric relationship between the sources and the sensors gives rise to crossed optical paths. At the point where the paths cross, the correlation value of the turbulence contributions will be at a peak. The correlation is shown to be mathematically related to the structure constant in terms of an integral of the structure constant multiplied by a path weighting function. It is shown that the path weighting function can be made to have the characteristics of a sampling function and the value of the structure constant can be directly inferred from the correlation measurement. The vertical resolution and signal-to-noise ratio are calculated for a sample case of two-layer turbulence.