Visiblelight source

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Uv sourcePython

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There are also various gas discharge lamps, e.g. xenon lamps and xenon/mercury lamps, which can be used for specific UV spectral lines or as broadband UV sources. Besides, there are excimer lamps, used as quasi-monochromatic UV sources in pulsed or continuous-wave mode. Particularly for the EUV region, gas discharges e.g. with xenon or with tin vapor or laser-induced plasmas are used for generating UV radiation with high powers of multiple watts or even dozens of watts. All such sources do not emit highly coherent radiation.

Artificial sources ofUV light

Will far UV-C light sources become available to the public for killing germs and viruses? It has been found that such light does not damage the skin or the eyes.

The technology of lasers for the generation of ultraviolet light faces various challenges; nevertheless, there are a few kinds of ultraviolet lasers which can directly generate UV light: some bulk lasers (e.g. based on cerium-doped crystals such as Ce:LiCAF), fiber lasers, laser diodes (mostly GaN-based), dye lasers, excimer lasers, and free electron lasers. Another way of generating ultraviolet light is by nonlinear frequency conversion of the outputs of near-infrared lasers. The article on ultraviolet lasers gives more details.

UV lightsources in home

UltraFast Innovations (UFI®) has developed a high-harmonic-generation (HHG) vacuum setup called NEPAL. It contains all required vacuum components (including the vacuum pump) and a fully motorized gas jet target for extreme ultraviolet (XUV) and soft X-ray generation. One can generate isolated attosecond pulses through HHG by injecting suitable femtosecond laser pulses.

light sourcein uv-visible spectroscopy

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Natural sources ofUV light

For handling UV light, special ultraviolet optics are required. A very high material quality in various respects is essential to avoid problems with parasitic absorption, scattering, degradation and others. See the article on ultraviolet optics for more details.

ultraviolet餐厅

Indeed, it appears to be an interesting idea that short-wavelength UV light (probably to be generated with excimer lamps) could be used for deactivating harmful germs e.g. in public rooms, apparently without causing negative health effects due to the very strong absorption of that light, e.g. in the tear layer on the human eye. However, I think it should first be extensively tested how effective that method really is and whether there are really no adverse health effects – e.g. by unwanted photochemical byproducts. It is at least conceivable that the method could be practical for widespread use.

For wavelengths below about 260 nm, there is also the problem that ozone is generated in air. It may thus be necessary to remove the ozone with suitable additional devices or to avoid its generation by avoiding the presence of oxygen.

UV light sourcespectrophotometer

There are also optical fibers which can guide ultraviolet light while avoiding substantial degradation (“solarization”). They are called solarization resistant fibers.

The optical breadboard inside the chamber is isolated from environmental vibrations for optimum temporal and pointing stability. A feedthrough with a noble gas inlet is included to supply e.g., argon, neon or helium for HHG in the spectral region of interest.

UV light finds a wide range of applications, including UV disinfection of water and tools, UV curing of adhesives, quality control for many materials and exciting fluorescence for analytical purposes. In the Covid-19 crisis, the ability of UV light to deactivate viruses has received increased attention.

Ultraviolet light is dangerous for the eyes (particularly for wavelengths in the range 250–300 nm) and for the skin (particularly for 280–315 nm) because it can cause cataracts or photokeratitis of the eye's lens and skin cancer, apart from hyperpigmentation and erythema. Lower doses, not yet causing acute effects, can accelerate aging of the skin. Therefore, work with UV light sources, in particular with UV lasers, demands special precautions for laser safety. For example, UV beams in optical setups usually have to be enclosed with metal tubes.

Various kinds of photodetectors can be used for the detection of ultraviolet light. These include devices based on the internal photoelectric effect, such as photodiodes, and others based on the external photoelectric effect, for example phototubes and photomultiplier tubes. Some of those are insensitive to visible and infrared light; they are called solar-blind photodetectors.

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