Glossary of Terms

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Aperture - describes an opening or device that regulates the amount of light emitted

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Ballast - the electrical component of many light sources; regulates the current flow through a lamp

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Condenser Lens - a type of lens used to narrow the output beam from a light source so as to increase the amount of light that reaches the image source (LCD panel) in a DIY projector; a means of increasing the efficiency of a light source

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DIY - (Do It Yourself); term used to refer to products or projects that are meant to be carried out at least in part by an individual; as opposed to "off the shelf"

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Emission - referring to the outward transmission of electromagnetic radiation; examples: radio waves, light, ultraviolet radiation, infrared radiation

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Fresnel Lens - typically a thin flat lens with optical properties similar to conventional (concave or convex) lenses; used in DIY projectors to disperse light evenly across the image source and recombine the light into a narrow region at a location just before the projection lens so as to intensify the brightness of the resulting projection; technology invented by Augustine Fresnel and subsequently used in most modern lighthouses to dramatically increase lighting efficiency

Focal Length - the distance between the lens and the focal point (region where the image is focused) for which the lens is focused on infinity; in DIY projectors, approximately the distance between a lens and the source it is to focus; typically measured in millimeters

Focal Point - distance from the lens at which the image is in focus

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Halide - highly reactive elements that are used in gaseous form in metal halide lamp technology to produce very bright and efficient light output

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IR or Infrared - heat radiation; the portion of the electromagnetic spectrum that includes radiation that transfers heat; a technology for transmitting information from a remote control to the device that it controls; commonly used in night-vision technology

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LCD - Liquid Crystal Display; the technology used to create the majority of modern flat-panel displays; as in a laptop video display

Lens - a means of focusing or condensing light, typically made of glass or other optical grade materials such as acrylic or plastic; used in DIY projectors both to form the projected image as well as to spread output from the light source evenly across the LCD panel

Light Source - literally the source of light; in a DIY projector, it typically consists of a metal halide lamp kit and a reflector for enhanced efficiency

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MDF - Medium Density Fiberboard; a dense, rigid alternative to particleboard or chipboard; used for projector enclosures and speaker cabinets because of its rigidity and cost effectiveness

Metal Halide - a lamp technology involving an electrical arc passing through a gas medium to produce light output; typically used in commercial and DIY video projectors as the light source; also used in automotive, industrial, and medical applications

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OTS - (Off The Shelf); referring to products that are mass produced and readily available to individual consumers at retail stores

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Point Source - referring to a light source that generates the majority of its light output from a very small region; theoretically, an emitter of light or radiation that exists only at a discrete point in space

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Triplet Lens - referring to a lens system that uses three optical elements internally; triplet lenses typically provide better optical resolution and geometric symmetry than do lenses of fewer elements

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Varifocal Lens - referring to a lens with adjustable focal length, typically enabling it to be focused dynamically without moving the lens position; as in a manual focus lens on a camera

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