Scattering of a Gaussian beam by stepped index Luneberg lens

The scattering and focusing characteristics of a Gaussian beam with phase d istribution is studied by a stepped index Luneberg lens. A model experiment was performed using a six-layer spherical lens. Two kinds of beams, that i s, broad and narrow beam are examined for the incident Gaussian beam. We fi nd that focusing effect of a narrow beam is wholly lower than that of a bro ad beam. The focal point is also shifted toward outer of sphere because of phase lag for the beam source. The spot size equals almost the wavelength f or the various beam parameters.