Overview Ultraviolet photography

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ultraviolet image of globular cluster ngc 1851 in southern constellation columba.


light visible human eye covers spectral region 400 750 nanometers. radiation spectrum used in normal photography. band of radiation extends 1 nm 400 nm known ultraviolet radiation. uv spectrographers divide range 3 bands:



near uv (380–200 nm wavelength; abbrev. nuv)
far uv (or vacuum uv) (200–10 nm; abbrev. fuv or vuv)
extreme uv (1–31 nm; abbrev. euv or xuv).

only near uv of interest uv photography, several reasons. ordinary air opaque wavelengths below 200 nm, , lens glass opaque below 180 nm. uv photographers subdivide near uv into:



long wave uv extends 320 400 nm, called uv-a,
medium wave uv extends 280 320 nm, called uv-b,
short wave uv extends 200 280 nm, called uv-c.

(these terms should not confused parts of radio spectrum similar names.)


there 2 ways use uv radiation take photographs - reflected ultraviolet , ultraviolet induced fluorescence photography. reflected ultraviolet photography finds practical use in medicine, dermatology, botany, criminology , theatrical applications.


sunlight available free uv radiation source use in reflected uv photography, quality , quantity of radiation depends on atmospheric conditions. bright , dry day richer in uv radiation , preferable cloudy or rainy day.


another suitable source electronic flash can used efficiently in combination aluminium reflector. flash units have special uv absorbing glass on flash tube, must removed before exposure. helps partly (90%) remove gold coating of flash tubes otherwise suppresses uv.


most modern uv sources based on mercury arc sealed in glass tube. coating tube internally suitable phosphor, becomes effective long wave uv source.


recently, uv-leds have become available. grouping several uv-leds can produce strong enough source reflected uv photography although emission waveband typically narrower sunlight or electronic flash.


special uv lamps known black light fluorescence tubes or bulbs can used long wave ultraviolet photography.







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