Beam shaping and beam splitting device and optical head comprising the

Abstract

A beam shaping and beam splitting device for converting a cross sectional shape of a polarized parallel incident light beam into a light beam having a corrected cross sectional shape, emanating the light beam toward a reflection surface and emanating a return light beam reflected by said reflection surface in a direction which is different from an incident direction of said incident light beam, including a prism made of an anisotropic material and having a first surface upon which said incident light beam is made incident from an incident direction which is inclined with respect to said first surface and a second surface from which the incident light beam emanates from the prism, in which said return light beam is refracted by said first surface and emanates from the first surface in a direction which is different from said incident direction. A separation angle between the incident light beam direction and the emanating direction of the return beam is mainly determined by a difference in the refractive indices of the prism for ordinary and extraordinary rays and can be made very small. In an optical head including such a beam shaping and beam splitting device, the light source and photodetector can be arranged nearer to each other, so that the optical head can be made small in size.