Slide projector

Many projectors have mechanical arrangements to show a series of slides loaded into a special tray sequentially.

This projector had provision to reduce lamp power by 20% to double its life (50 hours at full brightness).

[4] Light from the bulb is modified from a point source by reflection and passing through condenser lens(es) to generate a collimated beam, which is then directed through the slide.

A flat piece of heat-absorbing glass is usually placed in the light path before the slide, to avoid damaging the latter.

[3]: 42  In the United States, Eastman Kodak introduced Carousel slide projectors in 1961, which used a horizontal rotary cartridge like the namesake merry-go-round, and the format soon became ubiquitous there.

[13] Advantages of Carousel-type slide projectors include a simpler, gravity-fed mechanism, and the ability to automatically repeat the sequence of images without having to reload;[3]: 41  however, the circular trays tended to be bulkier and more expensive.

[7] By 1990, Rollei marketed the Rolleivision 35 Twin Digital, an upgraded P3800 which added a personal computer interface to control its operation.

A 1960 slide projector
Slide projector light generation and collimation system: from left to right, mirror / reflector , bulb , condenser lens 1, green-tinted heat-absorbing glass , condenser lens 2; a centrifugal fan , used to cool the bulb, is visible at the top of the picture.
Philips halogen lamp used in Carl Braun Camera-Werk Novamat M 330 slide projector
This slide projector, sold under the Zeiss Ikon brand, uses a straight-through tray; a thin arm grabs slides from a tray and puts them into the light path; the tray is advanced along its length. At the front of the projector, the protruding projection lens features rings to control focal length and focus.
Kodak Carousel S-AV 1050 , which features a horizontal rotary slide tray