Rayleigh distance Rayleigh distance Rayleigh distance in optics is the axial distance from a radiating aperture to a point at which the path difference between the axial ray and an edge ray is λ / 4. An approximation of the Rayleigh Distance is formula_1, in which Z is the Rayleigh distance, D is the aperture of radiation, λ the wavelength. This approximation can be derived as follows. Consider a right angled triangle with sides adjacent formula_2, opposite formula_3and hypotenuse formula_4. According to Pythagorean theorem, formula_5. Rearranging, and simplifying formula_6 The constant termformula_7 can be neglected. In antenna applications, the Rayleigh distance is
Live! Go for What You Know of Travers and Thrall bridged the gap between what it calls "dramatic changes" in metal in the late 1970s: Travers emblematized "the blues-rock sound of sixties and seventies metal" whereas Thrall's playing represents the newer wave in metal (represented by Eddie van Halen): "The combining of the two players' solos during this time showed a rare detente between two generations of hard rockers and, although short-lived, it was extremely exciting." The album was produced by Tom Allom, who had worked on the first five Black Sabbath albums as a sound engineer, had produced two albums by The Tourists, and would