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
The Crests group continued as a trio of Carter, Ancrum, and Lewis and became a lounge act, disbanding in 1978. Carter went to sing with Charlie Thomas' Drifters for a year, then moved to Plainfield, New Jersey, to teach voice and set up his own recording studio. In 1973, Carter met his wife Leona, an accomplished classical pianist/composer. Leona Carter has been a part of The Crests since then. Carter reformed The Crests in 1980, auditioning over 200 singers at his studio, finally settling on lead Bill Damon (a Maestro sound-alike), Greg Sereck, Dennis Ray and New York drummer, Jon Ihle. The