Autostereoscopic imaging systems based on holographic screen

Stereoscopic imaging systems require to have a mean of creating viewing zone(s) to make viewers to perceive images with a certain depth. Holographic screen is a kind of holographic optical elements, designed for both image projection and the viewing zone creation. It has properties of a lens + a diffuser for transmission type and a diffused or simple spherical mirror for reflection type. Making full color holographic screens with a desired property requires an extra process of making chirp-type fringes in the developing stage or stacking three primary color screens for the reflection type and aligning a long narrow slit type diffuser as an object m recording process for the transmission type. The holographic screen is an analogue type screen which can create many separated viewing zones for many viewers and with a reasonable depth. The viewing zone size is proportional to projector's objective exit pupil size. Hence it can be controlled for any desired size. Making any desired size screen is also possible, however, its focal length is proportional to its size. This is why the screen is allowed to be used for only projection type stereoscopic systems. The viewing angle obtainable with the screen can be up to 70 degrees in reflection mode operation. This angle is big enough for the multiview image projection. An image combiner for Head Up Display for cars is an example of a non-stereoscopic area of application.