The opaque projector, epidioscope, epidiascope or episcope is a device which displays opaque materials by shining a bright lamp onto the object from above. A system of mirrors, prisms and/or imaging lenses is used to focus an image of the material onto a viewing screen. Because they must project the reflected light, opaque projectors require brighter bulbs and larger lenses than overhead projectors. Care must be taken that the materials are not damaged by the heat generated by the light source. Opaque projectors are not as common as the modern "overhead".
Opaque projectors are typically used to project images of book pages, drawings, mineral specimens, leaves, etc. They have been produced and marketed as artists’ enlargement tools to allow images to be transferred to surfaces such as prepared canvas, or for lectures and discourses.
Famous quotes containing the word opaque:
“... people were so ridiculous with their illusions, carrying their fools’ caps unawares, thinking their own lies opaque while everybody else’s were transparent, making themselves exceptions to everything, as if when all the world looked yellow under a lamp they alone were rosy.”
—George Eliot [Mary Ann (or Marian)