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2. Overhead projector - Wikipedia

   en.wikipedia.org/wiki/Overhead_projector

   An overhead projector works on the same principle as a slide projector, in which a focusing lens projects light from an illuminated slide onto a projection screen where a real image is formed. However some differences are necessitated by the much larger size of the transparencies used (generally the size of a printed page), and the requirement ...

3. High-intensity discharge lamp - Wikipedia

   en.wikipedia.org/wiki/High-intensity_discharge_lamp

   15 kW xenon short-arc lamp used in IMAX projectors. High-intensity discharge lamps (HID lamps) are a type of electrical gas-discharge lamp which produces light by means of an electric arc between tungsten electrodes housed inside a translucent or transparent fused quartz or fused alumina arc tube. [1]

4. Halogen lamp - Wikipedia

   en.wikipedia.org/wiki/Halogen_lamp

   Halogen lamp (105 W) for replacement purposes with an E27 screw base A close-up of a halogen lamp capsule A halogen lamp (also called tungsten halogen , quartz-halogen , and quartz iodine lamp) is an incandescent lamp consisting of a tungsten filament sealed in a compact transparent envelope that is filled with a mixture of an inert gas and a ...

5. Opaque projector - Wikipedia

   en.wikipedia.org/wiki/Opaque_projector

   The opaque projector, or episcope is a device which displays opaque materials by shining a bright lamp onto the object from above. The episcope must be distinguished from the diascope , which is a projector used for projecting images of transparent objects (such as films), and from the epidiascope , which is capable of projecting images of both ...

6. Fresnel lens - Wikipedia

   en.wikipedia.org/wiki/Fresnel_lens

   An overhead projector in use. The use of Fresnel lenses for image projection reduces image quality, so they tend to occur only where quality is not critical or where the bulk of a solid lens would be prohibitive. Cheap Fresnel lenses can be stamped or molded of transparent plastic and are used in overhead projectors and projection televisions.

7. Ultra-high-performance lamp - Wikipedia

   en.wikipedia.org/wiki/Ultra-high-performance_lamp

   Ultra-high-performance lamp. An ultra-high-performance lamp, often known by the Philips trademark UHP, is a high-pressure mercury arc lamp. [1] These were originally known as ultra-high-pressure lamps, [2] [3] because the internal pressure can rise to as much as 200 atmospheres when the lamp reaches its operating temperature.