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| the bulb, base and inner structure that produces light. |
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| the proper name for the total lighting device that includes the lamp, reflectors, base and a possible shade (shield). |
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| a source that produces light by means of heating a tungsten filament to a point at which it glows. The gases may operate at a temperature in the range of 4000 degree f. |
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| a gaseous discharge light source that produces light by means of an electric arc that excites phosphors that coat the inner surface of the tube. |
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| High Intensity Discharge (HID) |
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Definition
| a gaseous discharge light source that contains a small tube with an electric arc that generates appreciable amounts of light. These sources may contain phosphors and additional filling gases for improved color. There generally are three types of these; Mercury Vapor, Metal-Halide (multi-vapor), and high pressure sodium. |
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| Light Emitting Diode (LED) |
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Definition
| a semi-conductor device with a chemical chip embedded in a plastic capsule. Light is focused or scattered using lenses or diffusers. |
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| the unit of measurement of light that strikes a surface…also referred to as incident light. |
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| the unit of measurement of light that is reflected from a surface. |
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| approximately 1897 with the creation of the first incandescent lamp. The first perfected lamp with an appreciable amount of light was created in 1906. Thomas Edison in the United States and Sir Joseph Swan in England were working independently on similar products. The first filament was made from bamboo that oxidized too quickly to be efficient. Modern products typically use tungsten as a filament. |
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| fluorescent light was introduced in the United States at the two worlds fairs that were running simultaneously in the United States in 1936 and 1937. |
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| approximately 1960 when the fashion (modeling) industry, photography and designers began to look at light production with greater attention to color and aesthetics. |
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| approximately 1974 bringing about energy conservative ideas and the promotion of low voltage lighting products. |
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| the thin light sensitive membrane on the inner surface of the rear of the eyeball. Typically compared to film in a camera. |
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| the parts of the eyeball responsible for movement and flicker. |
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| the parts of the eyeball responsible for color vision with the greatest concentration located in an area referred to as fovea. |
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| the process by which the eye locates and focuses on objects in the visual field. |
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| 130 degrees for vertical vision and 180 degrees for peripheral or horizontal vision. |
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| an aging eyeball. The inability of the eye to locate and focus on objects in the visual field. |
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| irregularities in the curvature of the cornea and lens making it difficult to bring verticals and horizontals into focus. |
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| Percentage brightness difference (PBD) |
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Definition
| the optical difference between two objects involving reflection of light. White-on-white is 0 percent PBD and black-on-white is 100 percent PBD. Always divide the smaller percentage by the larger. |
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| image is an active condition…mood is a passive condition |
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| relies on the processes of seeing which may involve visual defects and differing levels of visual perception from one client to the next |
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Definition
free light often associated with specific ranges of color seasonally and at different times in the day, heat, fading and glare.
➢ Glare can also be associated with man-made light sources…direct glare or indirect glare, veiling glare and disability glare |
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Definition
| analysis of hue, value and intensity (chroma) using the primaries of pigment (red, yellow and blue) and an analysis of spectral energy (red, blue and green) |
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| uniform ambient light, local lighting, and specific task light |
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| developing a “sense of place” by developing a design concept. Selling merchandise, drawing visitors into a space, making diners want to come back again. |
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| the rate at which electricity is transformed into some other form of energy…in this case visible radiant energy |
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| the measure of the total light output of a lamp. |
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| the total light “output” of a source divided by the total power “input”. In this case lumens divided by wattage = efficacy (efficiency). The average 40-60 is typically good. 60+ is an excellent rating for lamp efficiency. |
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Definition
| : typically equated as the total rated hours of life of the lamp. This may vary due to averaging some categories of light sources. This is used to determine cost factors involving the use electricity as measured in kilowatt Hours (kWh). For this study 1000 hours of usage is the variable with the billing rate of $0.10* per kWh. |
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| Correlated Color Temperature (CCT) |
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Definition
| a number indicating the degree of yellowness or blueness of a white light source measured in degrees Kelvin (k). The lower the CCT the more yellow the light will appear (2600-3100k). The higher the CCT the bluer the light will appear (7000-25,000 k). Light will appear whiter at a temperature near natural daylight or equal spectral energy (approx. 5000k). Manufacturers of CFL’s typically list the degrees kelvin (k) on the package for consumer comparisons. Manufacturers of incandescent products typically do not reference degrees Kelvin (k). These color temperatures are available by checking lamp specifications on-line using the product description (desc:) listed on the package. |
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| Incandescent Light Source |
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Definition
| produce light by means of heating a filament made from Tungsten to a point at which it glows. This is approximately 4000 degree f. |
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Definition
| produce light by means of an electric arc suspended in a vapor exciting phosphors that “glow” or produce visible radiant energy. |
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| Light-Emitting Diodes (LED) light sources |
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Definition
| produce light as a semi-conductor with chemical chips embedded in a plastic capsule. A volt from direct current (DC) energizes the chip and visible radiant energy is produced. |
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Definition
| visible light is measured in wavelengths known as this. ranges from 380 to 760 |
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| when the brain entertains two different depth hypothesis or visual sensations. perception may also be based on actual or apparent phenomenon. |
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| a tomato is red, gras is green |
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| environments with more stimuli |
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| environments with less stimuli |
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| shadowless with general levels of brightness. |
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| directive, creates a bright center, objects may be emphasized, focus on desired elements and separates them from surroundings or backgrounds. Consider levels of the principle of design known as emphasis from the most emphatic to subordinate to subdominate. |
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Definition
| brilliant displays of brightness and contrast. Example; the midway at a carnival. |
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| Seasonal Affective Disorder (SAD) |
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Definition
| known as the winter depression, is a mood disorder with many experiencing depressive behavior in the winter months. This is believed, by many researchers, to be related to light. Bright light therapy is believed to be a successful treatment to minimize or alleviate the effects of mood disorders that may lead depression, lack of energy and motivation and sleep disorders that may even lead to hospitalization. Adjusting the quantity and quality of light has been successful in the treatment of many with the disorder. |
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Definition
| patients experience the “sundown syndrome” associated with mood and behavior in the late afternoon and early evening. Adjusting light levels might ease these symptoms. However, studies have proven that noise, negative spaces such as looking out a dark window at night and other environmental factors are involved in the “sundown syndrome”. |
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Definition
| a common treatment for SAD. This consists of exposure to daylight or to specific wavelengths of light through the use of lasers, LED’s, fluorescent lamps or very bright (full-spectrum) light. Special light sources are available for this type of therapy |
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| Acne Vulgaris or psoriasis |
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Definition
| patients have found relief through the use of ultraviolet (UV) light due to the antibacterial effect it has on these disorders. Sunlight was also found in some instances to be as or more effective in such treatment. |
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| Phototherapy, Photomedicine and Photobiology |
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Definition
| all sciences that deal with the effects of light and the healing process and the interactions of light to living organisms. These study the quantity and quality of light, the positive effects of producing Vitamin D, killing bacteria, curing jaundice in infants, vision and mood disorders and such serious disorders as Alzheimers. |
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Definition
| sleep disorders affect the timing of sleep. People are unable to sleep and wake at times required for work, school, and social events. Exposure to light at certain intervals may be essential in treatment. However, geographic location and seasonal effects of light and darkness also play an important role in therapy. |
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Definition
| the sensation that occurs in the consciousness of the human observer. This is typically considered “subjective” due to the fact that people perceive light as well as other interior components in different ways. |
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Definition
| the measurement of intensity of light. This is objective due to the fact that it can be quantified and qualified. |
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Definition
| Can be used to emphasize texture as light grazes the surface creating areas of shadow and areas of brightness. |
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Definition
| created by too much light directed at the human eye from the lighting system. |
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Definition
| created by light being reflected from surfaces or objects not necessarily a result of too much light. |
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Term
| Visual Comfort Probability (VCP) |
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Definition
| ➢ The percentage of people when seated in the least desirable location in an office work space that find the lighting installation comfortable. |
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Definition
| example = exposed christmas tree lights. |
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Definition
| example = chandeliers emitting light through diffuse or etched glass or other translucent materials. |
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| example = textured metallic surfaces. |
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Definition
➢ Measured in degrees kelvin (K)
➢ This is not the surface temperature of a light source but rather the visible radiant light that “matches” a certain wavelength of light. |
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Definition
| expresses how colors (hues/pigments) appear under a given light source (spectral energy). |
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| color rendering index (cri) |
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Definition
| establishes a color temperature of a light source and the comparison of that light source to objects or surfaces. |
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Definition
| the name of a color and it’s corresponding position on the color wheel. |
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Definition
| the degree of lightness or darkness of a color. |
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Definition
| the degree of saturation, purity or strength of a color. |
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Definition
| ➢ Arranges lettered color chips in triangles and describes them in terms of purity, whiteness, and blackness. |
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Definition
➢ Provides greater accuracy in identifying color.
➢ A theoretical solid form rather than a globe.
➢ The vertical axis is graduated into nine shades of gray with white at one end and black at the other.
➢ The “colors” are divided into 20 basic hues in pie sections with purest color located at the perimeter of the solid form. |
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Term
| law of simultaneous contrast |
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Definition
➢ Contrast provided by the interaction of hues through changes in value or intensity.
➢ Objects may appear to be brighter when placed against dull or neutralized backgrounds.
➢ Objects may appear duller when placed against brighter backgrounds
➢ Objects may appear closer or farther away, larger or smaller when placed in juxtaposition to a variety of duller or brighter backgrounds. |
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Term
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Definition
is “Sunlight”.
➢ The directional beam emitted by the sun.
➢ Direct sunlight is typically impractical for interior applications unless it is controlled by shielding mechanisms or other means to redirect it.
“Skylight”.
➢ Light that is diffused (spread) from particles in the atmosphere.
➢ This can be a useful source without shielding but may still require some control especially when lighting horizontal task surfaces…the angle of incidence is equal to the angle of reflection. |
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Definition
| ➢ The medium base is the most common. Lamp bases are made to specific sizes to accommodate certain electrical components. For instance, a lamp requiring very high voltage would not have a base that could be inserted into a regular standard voltage receptacle. This protects not only the lamp but the human installer as well. |
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Definition
➢ The filament in an incandescent lamp is made from Tungsten which can withstand very high temperatures.
➢ The filament can be straight, coiled “c” or double coiled “cc”. The amount of filament is what produces illumination in small or large quantities. |
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Definition
➢ Most incandescent lamps use a filling gas contained in a vacuum to retard the oxidation of the tungsten filament. Typical gases include argon, nitrogen or krypton and in some instances a combination of two or more.
➢ Filling gases also retard bulb blackening which is caused by a build-up of tungsten particles on the inner surface of the bulb wall. |
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Definition
➢ Dimming can lead to energy conservation…but…the downside is some products may not have as a long a life span if dimmed.
The most popular is the resistance dimmer that work on the principle of holding back electrons.
➢ If dimming the same lighting system from more than one location it is necessary to use a programmable dimmer |
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Definition
| ➢ Use halogen gases to help retard the evaporation of the filament and typically deliver almost full light output throughout its life. |
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Definition
➢ Operate at lower voltages and provide precise beam control.
➢ Require a transformer to reduce line voltage to lower voltage.
➢ One type of popular beam precise lamp which can operate at regular or lower voltages is the multi-faceted mirror reflector (MR) source commonly used in projectors. |
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Definition
➢ Gelatin or “gel” filters are thin, colored transparent plastic sheets used in conjunction with incandescent products.
➢ Colored plastic panels are available for use with fluorescent lamps. |
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Definition
➢ Incandescent colored lamps for signage and decorative features often use outside ceramic enamels, sprayed finishes or dipped coatings.
➢ Transparent ceramic enamels are used to coat clear glass bulbs.
➢ Sprayed finishes such as shellacs or silicones are applied to the complete lamp.
➢ Dichroic interference filters are deposited on the inside of the lens cover that transmit only the desired color or wavelengths of light. |
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Definition
| The U.S. Energy Policy ACT of 1992 established minimum average efficacy (efficiency) standards for the R and PAR incandescent lamps that operate between 115 to 130 volts |
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Definition
➢ Light production is more efficient than electric heating methods in filament lamps.
➢ Fluorescent lamps are low-pressure mercury arc discharge sources. An electric arc is passed between two cathodes, one at each end of the lamp.
➢ When the electric arc is complete mercury ionizes (vaporizes) to fill the inside of the bulb. This vapor strikes the tube wall and phosphors are excited and fluoresce or become luminous. |
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Definition
➢ Fluorescent lamps require a ballast to regulate the electric current. Three types of mechanisms are available:
➢ Preheat: the oldest type taking a few seconds to “pre” heat the circuit using a “starter”..
➢ instant-start: does not require a starter which simplifies the circuitry.
➢ rapid-start: combines the features of pre-heat and instant start. Starters are unnecessary. |
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Definition
| ➢ T12 versus T8 and T5 : this involves the amount of glass tube used, phosphorescent materials and wattage. |
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Definition
| During the first 100 hours of usage the lumen rating of most fluorescent lamps drops by 5 %. After that lumen reduction is less rapid which is a valued feature for efficacy. |
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Definition
| This is another valued attribute of fluorescent lamps due to the fact that a huge range of lamp life exists from 7,500 hours to 24,000. |
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Definition
| This is another valued attribute of fluorescent lamps due to the fact that a huge range of lamp life exists from 7,500 hours to 24,000. |
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Definition
➢ Produce light by passing an electric current through a gas or vapor operating at high voltage.
➢ Mercury Vapor: produces light using mercury vapor.
➢ Metal Halide: or “multi-vapor” produces light using combined vapors of mercury and metal halides.
➢ High Pressure Sodium: produces light using combined vapors of mercury and sodium with the later being the dominant color source producing an orange tinted color. |
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Definition
| reduce or lower regular voltage for use by special lamps capable of producing light by using less voltage. |
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Definition
| limits current flow and regulates the correct voltage to start the arc discharge. |
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Definition
| uses coils of copper or aluminum to covert electrical power into some form appropriate to start and regulate the lamp. |
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Definition
| ➢ The effect of light emitted from LED |
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Definition
| a material that is neither a good conductor of electricity (like copper) nor a good insulator ( like rubber). One of the most common materials is silicon. An example of the use of semiconductors is the computer chip for a CPU and memory. |
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Definition
➢ The first reported use of light-emitting diodes was in 1907 by H.J. Round of the Marconi Company (British experimenter).
➢ The first practical use of LED for a visible spectrum (red) was in 1962 with research being done by General Electric. |
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Definition
➢ Organic materials such as a polymer may be used to provide greater flexibility of the source. These are lighter than the regular LED.
➢ Some practical applications of this product are: light sources, flexible displays (bending or wrapping), luminous cloth and wall decorations, portable devices such as cellphones, MP3 players and digital cameras. |
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Term
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Definition
the return of light from a surface
Specular reflection: light reflected from a smooth, highly polished surface such as a mirror. The angle of incidence is equal to the angle of reflection.
➢ Semi-specular (spread) reflection: irregular surfaces that spread the reflected light beam.
➢ Diffuse reflection: light is reflected from each point on the surface in all directions with maximum intensity perpendicular to the surface. |
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Term
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Definition
➢ Elliptical contour: has two focal points. Light originating at one focal point is reflected through a second producing a divergent beam which spreads light.
➢ Parabolic contour: two focal points placed far apart create a parallel beam of light.
➢ Circular contour: light rays are reflected back through the focal point for visual intensity. |
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Term
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Definition
light through a material that is affected by two things (1) surface reflections and (2) absorption and redirection within the material known as refraction (bending light between two different optical densities). Example: a pencil propped in a glass of water will appear to be bent.
➢ Direct transmission: transparent materials leave light distribution unchanged.
➢ Semi-diffuse (spread) transmission: translucent materials emit light at wider angles because of configurations on at least one side of the material.
➢ Diffuse transmission: disperses light in all directions. |
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Definition
| light appears to bend at the point where optical densities change from lesser to greater density. |
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Definition
| control distribution of light and in some instances control direction. |
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Definition
| produces a concentrated beam of light while reducing the brightness of the source providing a degree of glare control. |
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Definition
| light entering one end of a glass or plastic fiber of optical quality is transmitted to the other end in the process of total reflection. |
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Definition
➢ Baffles provide shielding in one direction.
➢ Louvers provide shielding from many directions. |
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Definition
➢ Veiling glare generally controlled by altering the source of light or the task to alter the angle of incidence or reflection.
➢ Disability glare is a strong beam of light allowed to interfere with the normal ranges of vision in vertical or horizontal vision slowing the natural process of accommodation in the eyeball. |
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Definition
| the science that measures light |
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Definition
| light emitted in a specific direction measured in candelas or candlepower. |
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Definition
| light emitted in all directions measured in lumens |
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Definition
| density of light at any given point on a surface measured in (fc) footcandles. |
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Definition
| light that is reflected from a surface in a given direction. |
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Definition
| the quality of light emitted, reflected or transmitted in all directions from a surface. |
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Definition
| the quality of light emitted, reflected or transmitted in all directions from a surface. |
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Definition
| The day-night cycle of plant growth. By adjusting prolonged periods of daylight or darkness plants can be forced to grow. Day blooming plants are forced into prolonged periods of daylight and night blooming the opposite. |
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Definition
LLF: as a system ages a depreciation in light output occurs known as light loss factor. Dirt appreciation and accumulation of dust on luminaire surfaces can cut light output. Temperatures, voltage factors, ballast factors can also effect light output over the life of a source.
LLD: usually a result of light depreciation over time as the filament evaporates, depositing tungsten on the bulb wall or from phosphor degradation.
LDD: luminaire dirt depreciation.
CU: coefficient of utilization refers to the expected percentage of light output from a specific luminaire in a room. Efficiency is the overall concern when dealing with CU. |
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