Stereo projection of pictures using overhead projector - has projection condenser lenses adapted to split light from light source before passage through pictures

摘要

The device for the projection of stereo pictures is constructed from an overhead type projector system, and the condenser lens system is so reconstructed as to split the light emanating from a conventional light source and pass it through the projection stage, in the beams, one beam passing through each of the two stereo pictures. The picture holders are capable of being moved relative to one another by means of a pusher crank motion to ensure correct alignment of the projected images. The condenser consists of two fresnel lenses, one for each stereo picture; and it may consist of two layers. The first layer may be a single fresnel lens which refracts the divergent light rays from the lamp until they are parallel, and the two lenses in the second layer make the rays converge.