An overhead projector is a display system that is used to display images to an audience. They typically consist of a large box containing a very bright lamp and a fan to cool it, on top of which is a large lens that collimates the light. Above the box, typically on a long arm, is a mirror that redirects the light forward instead of up. Collimated light is light whose rays are parallel. ...

Transparencies are placed on top of the lens for display. The light from the lamp travels though the transparency and into the mirror where it is shone forward onto a screen for display. The mirror allows both the presenter and the audience to see the image at the same time, the presenter looking down as if writing, the audience looking forward at the screen. A transparency is a thin sheet of transparent flexible material, typically celluloid, onto which figures can be drawn. ... Projection screens are installations consisting of blank surface and a support structure used for projecting an image for the view of an audience. ...

Overhead projectors were once a common fixture in most classrooms and business conference rooms, but today are being replaced by larger computer monitors and dedicated computer projection systems. Critics feel that there are some downsides as they are much more prone to failure and have a much steeper learning curve than a standard overhead projector. Although with a computer projection system, there is no longer a need to create hard copy transparencies of the slide show presentation. Slideshow is a modern concatenation of Slide Show. A slideshow is a display of a series of chosen images, which is done for artistic or instructional purposes. ...

• Pop culture reference
  • "Farewell to Overhead": In 2005 the group monochrom created a melancholic electro pop song about the "dead medium" overhead projector and adolescence/socialisation.

monochrom is an international art-technology-philosophy group (founded in 1993). ... Look up pop on Wiktionary, the free dictionary. ... Adolescence is the transitional stage of development between childhood and full adulthood (gender-specific manhood, or womanhood), representing the period of time during which a person is biologically adult but emotionally not at full maturity. ... In psychology, socialization is the process by which children and others adopt the behavior patterns of the culture that surrounds them. ...

Related

A related type of the projector is the opaque projector. The opaque projector, episcope or epidiascope is a predecessor to the overhead projector. ...

See also

• Projector for a directory of projector types