light, episcopic." Two main classes of opaque projectors thus existed: the episcope, which solely projected images of opaque objects the epidiascope, which was capable of projecting images of both opaque and transparent images See also Projector (disambiguation) for a directory of projector types. Telop References External links Episcopes and epidiascopes, photographs of a collection. Historic Ross Epidiascope Patent #803.385 for one of the earliest epidiascopes Projectors Display devices