屈折率が一様な球形レンズの集束特性

概要

論文の詳細を見る
The liquid filled spherical lenses have been investigated by several authors. Though the lenses of this type have some advantages, they are structually delicate. In this paper, the homogenous spherical lenses are constructed by molding the mixture of RTV silicon rubber and zinc powder. The focusing properties of them are measured and compared with the calculated results for the lens diameter to wavelength ratios smaller than 25. It is shown that the pressure gain, the position of the focal point, and the beamwidth are determined by the index of refraction and k_a (k:the wavenumber in water;a:the radius of lens). The position of the focal point moves outward, oscillating back and forth along the lens axis as the k_a increases. Although the pressure level at the surface of lens increases with the index of refraction, the pressure fluctuation also increases so that the lens with the index of refraction near 1. 55 is useful at small values of k_a(k_a<20). It is shown that the mixture of RTV silicon rubber and zinc powder is a useful lens material.
社団法人日本音響学会の論文
1978-12-01