Vol. 11, issue 11, article # 10

Abstract:

We describe here a differential optical meter of the parameters of atmospheric turbulence. It reduces the contribution of relative shifts of the radiation source and receiving system to the error of the parameters’ determination. Determination of the structure constant of the refractive index and of the Fried radius is based on detecting random image jitter caused by the atmospheric turbulence. We estimate the degree of suppression of the angular displacements of the source in the spectrum of the difference signal compared to the same component in the signal spectrum at the output of a single-channel meter. The values C²_n are measured under angular displacements of the source in the frequency range 0–130 Hz by the single-channel and differential methods. The contribution coming from these displacements to the error of C²_n determination from the differential measurements is shown to be reduced by approximately 50 times at the amplitude of angular fluctuations of the source being 3 seconds of arc.