visible spectrum


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spectrum

 [spek´trum] (L.)
1. the series of images resulting from the refraction of electromagnetic radiation (e.g., light, x-rays) and their arrangement according to frequency or wavelength.
2. range of activity, as of an antibiotic, or of manifestations, as of a disease. adj., adj spec´tral.
absorption spectrum one obtained by passing radiation with a continuous spectrum through a selectively absorbing medium.
broad-spectrum effective against a wide range of microorganisms.
visible spectrum that portion of the range of wavelengths of electromagnetic vibrations (from 770 to 390 nanometers) which is capable of stimulating specialized sense organs and is perceptible as light.

vis·i·ble spec·trum

that part of electromagnetic radiation that is visible to the human eye; it extends from extreme red, 7606 Ǻ (760.6 nm), to extreme violet, 3934 Ǻ (393.4 nm).

visible spectrum

Etymology: L, visibilis, vision, spectrum, image
the colors of the spectrum that can be observed by most people, from violet at about 4000 angstrom units (400 nm) through blue, green, yellow, and orange, to red, at about 6500 angstrom units (650 nm).

vis·i·ble spec·trum

(viz'i-bĕl spek'trŭm)
That part of electromagnetic radiation that is visible to the human eye; it extends from extreme red, 7606 Å (760.6 nm), to extreme violet, 3934 Å (393.4 nm).

visible spectrum

see ELECTROMAGNETIC SPECTRUM.

light

Electromagnetic vibration capable of stimulating the receptors of the retina and of producing a visual sensation. The radiations that give rise to the sensation of vision are comprised within the wavelength band 380-780 nm. This band is called the visible spectrum or visible light. The borders of this band are not precise but beyond these radiations the visual efficacy of any wavelength becomes very low indeed (less than 10−25). See coherent sources; infrared; absorptive lens; spectroscope; electromagnetic spectrum; visible spectrum; Table C4; quantum theory; wave theory; ultraviolet; wavelength.
achromatic light See achromatic light stimulus.
light adaptation See light adaptation.
artificial light Any light other than natural light.
beam of light A collection of pencils arising from an extended source or object. Syn. bundle of light. See pencil of light.
bundle of light See beam of light.
light chaos See idioretinal light.
cold light Any visible light emitted by a process other than incandescence such as lasers, glow worms, certain chemical reactions, etc. Cold light is free of infrared.
compound light Light composed of more than one wavelength.
diffuse light Light coming from an extended source and having no predominant directional component. Illumination is thus relatively uniform with a minimum of shadows. See diffusion; extended source.
fluorescent light Light emitted by fluorescence as in a fluorescent lamp. Electricity excites a gas that produces ultraviolet light, which in turn causes a phosphor coating on the inner surface of the fluorescent tube to fluoresce and emit visible light. Examples: mercury vapour lamp, neon and argon lamps, sodium vapour lamp, xenon flash lamp.
frequency of light See hertz; electromagnetic spectrum; wavelength.
idioretinal light A visual sensation occurring in total darkness that is attributed to spontaneous nervous impulses in the neurons of the visual pathway. Syn. intrinsic light; light chaos.
incandescent light Light emitted by incandescence as in an incandescent lamp. An electrical current passes through a thin filament (e.g. tungsten) enclosed in a sealed oxygen-free glass bulb. The filament is heated and photons are released. See filament lamp; halogen lamp.
infrared light See infrared.
intrinsic light See idioretinal light.
monochromatic light Light consisting of a single wavelength or, more usually, of a narrow band of wavelengths (a few nanometres).
natural light Light received from the sun and the sky.
pencil of light A narrow cone of light rays coming from a point source or from any one point on a broad source after passing through a limiting aperture. A pencil of light may be convergent, divergent or parallel. The ray passing through the centre of the aperture is the chief ray. Syn. homocentric bundle of rays; homocentric pencil of rays. See beam of light.
polarized light Ordinary light is composed of transverse wave motions uniform in all directions in a plane perpendicular to its direction of propagation. Polarized light is composed of transverse wave motions in only one direction, called the plane of vibration. Polarized light can be obtained by using a polarizer (e.g. tourmaline crystals, polarizing material such as Polaroid, Nicol prism, etc.). See analyser; angle of polarization; dichroic crystal; polarizing lens; polarizer; Wollaston prism; vectogram.
quantity of light Product of luminous flux and its duration. Unit: lumen-second. See lumen.
light reflex See corneal reflex; pupil light reflex.
solar light Light from the sun or having identical properties as the sun. See eclipse blindness; white light.
light source Any source of visible radiant energy such as natural light (e.g. daylight, moonlight, sunlight) or artificial light (e.g. a candle flame, an incandescent lamp, a discharge lamp, a fluorescent lamp). See coherent sources; CIE standard illuminants.
speed of light The currently accepted figure is 299 792.5 km/s (in a vacuum). This velocity decreases, differentially with wavelength, when the radiation enters a medium. See index of refraction; electromagnetic spectrum.
light stop See diaphragm.
stray light Light reflected or passing through an optical system but not involved in the formation of the image such as that reflected by the surfaces of a correcting lens. Syn. parasitic light. See ghost image.
light threshold See light absolute threshold.
ultraviolet light See ultraviolet; Wood's light.
visible light See light; visible spectrum.
white light Light perceived without any attribute of hue. Any light produced by a source having an equal energy spectrum will appear white after the eye is adapted. Some of the CIE illuminants are often used as a source of white light, e.g. B, C and D. Sunlight is a source of white light. See chromaticity diagram; equal energy spectrum.
Wood's light Ultraviolet light near the visible spectrum which, when used with certain dyes such as fluorescein, causes fluorescence. It is produced by a special type of glass (called Wood's glass or Wood's filter), which contains nickel oxide and transmits ultraviolet radiations near the visible spectrum. It is used to detect corneal abrasions and to evaluate the fit of hard contact lenses. It is available in a slit-lamp or in a Burton lamp. See fluorescein; fluorescence; Burton lamp.

spectrum

pl. spectra, spectrums [L.]
1. the series of images resulting from the refraction of electromagnetic radiation (e.g. light, x-rays) and their arrangement according to frequency or wavelength.
2. range of activity, as of an antibiotic, or of manifestations, as of a disease.

absorption spectrum
one obtained by passing radiation with a continuous spectrum through a selectively absorbing medium.
antibacterial spectrum
the range of bacteria susceptible to a particular antimicrobial or class of antimicrobials.
broad-spectrum
effective against a wide range of microorganisms.
visible spectrum
that portion of the range of wavelengths of electromagnetic vibrations (from 770 to 390 nanometers) which is capable of stimulating specialized sense organs and is perceptible as light.
References in periodicals archive ?
These lenses, known as "Harris Lenses" (Figure 1) (patent pending), produce the clinical benefits required for reading difficulties but reflects light more equally across the visible spectrum, thus giving a neutral appearance to an outward observer (Figure 2).
When you dim them, their color shifts to the red (warm) end of the visible spectrum.
The enhancement enables high resolution imagery resulting from fluorescence excitation from all three lasers to be captured simultaneously across the entire visible spectrum.
Applied physics researchers at the California Institute of Technology, Pasadena, have constructed a nanofabricated photonic material which creates a negative index of refraction in the blue-green region of the visible spectrum.
Emerging strategies are aimed at taking advantage of the full physical spectrum, including sound, the visible spectrum, and radio waves.
Who decided that future generations should be illuminated by low energy light bulbs that fail to emit three of the essential wavelengths of the visible spectrum of colour interpreted by the human eye/brain?
Lower frequencies of the visible spectrum are red and higher frequencies are blue.
Dot Metrics achieved this breakthrough via a proprietary process sequence that produces a higher efficiency electroluminescent output, tunable to the deep-green portion of the visible spectrum.
The NIR instrumentation can precisely determine the starch-protein ratio in rice by measuring light just beyond the visible spectrum.
Instructions on how to mix primary colors to produce virtually every color and every gradation in the visible spectrum are included.
Exciplex formation generates a broad band of emission wavelengths across the visible spectrum, which becomes viewed as white.