Light guide device enhancing a polarized component and liquid crystal

Abstract

A polarized component is obtained with a high conversion efficiency in a light guide which produces one of the polarized components by having it transmitted. The light from a light source is incident to a light guide which comprises a plurality of light guide layers and reflected by the end surface to an interface between the light guide layers. The polarized component transmitting through the end surface is rotated in its polarization plane by a wave length plate and reflected by a reflecting plate for reentrance to the light guide at the end surface of the light guide toward the interface. The reentering light mostly transmits through the interface because the polarization plane is rotated. A reflected light polarized component is returned to the wave length plate and the reflecting plate, and directed back to the interface again. The polarized component transmitting through the interface is similarly transmitted and reflected in the next interface. The number of interfaces can be reduced by increasing the reflection of the polarized component reflected in the interface. For this purpose, the index of refraction in the direction along the axis of the reflected polarized component is increased by making the index of refraction of the light guide layer anisotropic.