A
slide projector is an opto-mechanical device to view
photographicPhotography is the process, activity and art of creating still or moving pictures by recording radiation on a sensitive medium, such as a photographic film, or an electronic sensor...
slides. It has four main elements: a fan-cooled electric
incandescent light bulbThe incandescent light bulb, incandescent lamp or incandescent light globe is a source of electric light that works by incandescence . An electric current passes through a thin filament, heating it until it produces light...
or other light source, a reflector and "condensing" lens to direct the light to the slide, a holder for the slide and a focusing
lensA lens is an optical device with perfect or approximate axial symmetry which transmits and refracts light, converging or diverging the beam. A simple lens is a lens consisting of a single optical element...
. A flat piece of heat absorbing glass is often placed in the light path between the condensing lens and the slide, to avoid damaging the latter.
A
slide projector is an opto-mechanical device to view
photographicPhotography is the process, activity and art of creating still or moving pictures by recording radiation on a sensitive medium, such as a photographic film, or an electronic sensor...
slides. It has four main elements: a fan-cooled electric
incandescent light bulbThe incandescent light bulb, incandescent lamp or incandescent light globe is a source of electric light that works by incandescence . An electric current passes through a thin filament, heating it until it produces light...
or other light source, a reflector and "condensing" lens to direct the light to the slide, a holder for the slide and a focusing
lensA lens is an optical device with perfect or approximate axial symmetry which transmits and refracts light, converging or diverging the beam. A simple lens is a lens consisting of a single optical element...
. A flat piece of heat absorbing glass is often placed in the light path between the condensing lens and the slide, to avoid damaging the latter. This glass transmits visible wavelengths but absorbs
infraredInfrared radiation is electromagnetic radiation whose wavelength is longer than that of visible light , but shorter than that of terahertz radiation and microwaves...
. Light passes through the
transparentIn the field of optics, transparency is the physical property of allowing light to pass through a material. The opposite property is opacity. Transparent materials are clear . Translucent materials allow light to pass through them only diffusely In the field of optics, transparency is the physical...
slide and lens, and the resulting image is enlarged and projected onto a perpendicular flat
screenA projection screen is an installation consisting of a surface and a support structure used for displaying a projected image for the view of an audience. Projection screens may be permanently installed as in a movie theater, painted on the wall , semi-permanent or mobile, as in a conference room or...
so the audience can view its reflection. Alternatively the image may be projected onto a translucent "rear projection" screen, often used for continuous automatic display for close viewing. This form of projection also avoids the audience interrupting the light stream by casting their shadow on the projection or by bumping into the projector.
Slide projectors were common in the 1950s and 1960s as a form of entertainment; family members and friends would gather to view slideshows.
In-home photographic slides and slide projectors have largely been replaced by low cost paper prints, digital cameras,
DVDDVD, also known as Digital Versatile Disc or Digital Video Disc,is an optical disc storage media format, and was founded in 1995. Its main uses are video and data storage...
media, video display monitors and
video projectorA video projector takes a video signal and projects the corresponding image on a projection screen using a lens system. All video projectors use a very bright light to project the image, and most modern ones can correct any curves, blurriness, and other inconsistencies through manual settings...
s.
As of October 2004,
Eastman KodakEastman Kodak Company is a multinational US corporation which produces imaging and photographic materials and equipment. Long known for its wide range of photographic film products, Kodak is re-focusing on two major markets: digital photography and digital printing.- Origins :Kodak's origins rest...
no longer manufactures slide projectors. It is also increasingly difficult in some countries to locate photo processors who will process slide film.
Types of projector
- Carousel slide projector
A carousel slide projector is a common form of slide projector, used to project slide photographs and to create slideshows. The first carousel slide projector was invented by Louis Misuraca, who immigrated to the United States from Naples, Italy when he was a child. Louis was paid a one-time fee...
s (includes tray-style projectors)
- Dual slide projectors
- Overhead projector
An overhead projector is a variant of slide projector that is used to display images to an audience.-Mechanism:An overhead projector typically consists of a large box containing a very bright lamp and a fan to cool it. On top of the box is a large fresnel lens that collimates the light...
s
- Single slide projectors (manual form)
- Viewer slide projectors
- Slide Cube projector
A slide cube projector is a type of slide projector that was created by Bell & Howell and was sold up through the 1980s. The system gets its name from the plastic cubes that slides are stored in...
s
- Stereo slide projectors (projects two slides simultaneously with different polarization
Polarization is a property of waves that describes the orientation of their oscillations. This article primarily covers the polarization of electromagnetic waves such as light, although other types of wave also exhibit polarization....
s; slides appear as three-dimensional with polarizing glasses)
- Large Format Slide Projector
A Large Format Slide Projector is a kind of slide projector which has a very powerful light source...
for uses on stages, for events or for architectural and advertising issues of high light output needs.