Abstract
The quadratic approximation is used to derive a procedure for computing the mean-square intensity in a channel excited by a partially coherent source, using the characteristics (rays of geometrical acoustics) of the four-point coherence equation, and their properties. The procedure is employed to obtain exactly the scintillation field of a partially coherent Gaussian beam emerging from a weak phase screen into a quadratic channel. A simple approximate formula for the mean-square intensity in the farfield of a localized source is derived and tested:It is found to closely reproduce the aforementioned exact result for a quadratic channel, except for the immediate vicinity of focal planes. Various modes of application of the approximate formula are discussed.
| Original language | English |
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| Pages (from-to) | 1399-1405 |
| Number of pages | 7 |
| Journal | Journal of the Acoustical Society of America |
| Volume | 81 |
| Issue number | 5 |
| DOIs | |
| State | Published - May 1987 |