History
The opaque projector is a predecessor to the overhead projector. The light source in early opaque projectors was often limelight. Incandescent light bulbs and halogen lamps are most commonly used today. In the early and middle parts of the 20th century, low-cost opaque projectors were produced and marketed as toys for children.
In educational settings, the specific role of the opaque projector has been superseded by the document camera, a lighted table with a fixed video camera above it. The image from the camera is displayed using a separate projector. The document camera is also called a desktop presenter unit or opaque projector.
Read more about this topic: Opaque Projector
Famous quotes containing the word history:
“Don’t you realize that this is a new empire? Why, folks, there’s never been anything like this since creation. Creation, huh, that took six days, this was done in one. History made in an hour. Why it’s a miracle out of the Old Testament!”
—Howard Estabrook (1884–1978)
“The history is always the same the product is always different and the history interests more than the product. More, that is, more. Yes. But if the product was not different the history which is the same would not be more interesting.”
—Gertrude Stein (1874–1946)
“The one duty we owe to history is to rewrite it.”
—Oscar Wilde (1854–1900)