Adaptor for overhead projector

摘要

Apparatus for converting an overhead projector to use photographic slides includes a fresnel disk that shortens the illumination convergence point to match the focal length of a typical slide projector. The apparatus includes a base that covers the platen of the overhead projector to prevent illumination spillover, and supports projection optics over an aperture that admits illumination for projecting magnified images of slides onto a vertical viewing surface.