Quartz lamp
The quartz lamp is a gas discharge lamp filled with mercury vapor ( mercury vapor lamp with a discharge vessel made of quartz glass ) and is used to generate UV radiation . The discharge vessel blocks a substantial part of the UVC radiation for therapeutic purposes , which is not necessarily the case with burners of high-pressure mercury vapor lamps.
The high-pressure discharge vessel is not in a protective glass bulb, as is the case with lamps for lighting purposes, but is usually free without protection to allow the hard UV radiation to pass through. Like fluorescent lamps or fluorescent tubes, low-pressure quartz lamps are not made of normal glass coated with fluorescent material, but of clear quartz glass.
The quartz lamp is used in medicine , forensics and science , as well as partly in photography for special illumination. Further applications are disinfection (drinking water) and photolithography .
Medical use
In the past, quartz lamps were often used in medicine for radiation purposes (the sunlamp , however, is a high-pressure mercury vapor lamp). This leads to photochemical reactions and the development of photochemical erythema ( pigmentation ). They were used to treat rickets and osteomalacia , as the radiation in the skin produces the provitamin D3 . In addition, it kills bacteria and is therefore often used in hospitals and for the treatment of acne and other skin diseases. A special case is the "cold" quartz lamp, which was developed by the founder of the Wienerwald sanatorium , Hugo Kraus, in 1931/32 for irradiation of larynx tuberculosis.
With the potential to trigger skin cancer, these therapies have gone out of fashion.
Today only low-pressure mercury vapor lamps , similar to fluorescent lamps, are used in solariums ; these only emit in the soft ultraviolet. The use of solariums is still controversial.
Criminal and scientific use
In criminology , among other things, counterfeit stamps can be detected, as changes in the brand image or imprint compared to the original can be seen with the quartz lamp. Quartz lamps or the so-called " black light lamps " that emit primarily in UV-A with a UV fluorescent substance are not only used to uncover counterfeit stamps, but also to reveal counterfeit materials or secret writing . Quartz lamps have also proven their worth for finding scraped writing on parchment . Among other things, Cicero's writing “ De re publica ” was rediscovered in the Vatican .
Technical use
As UV emitters, they are used in science to e.g. B. to calibrate spectrometers based on the line spectrum or to stimulate fluorescence markers .
Compact low-pressure lamps of low power are often used to erase EPROMs .
Further applications are the curing of UV-sensitized synthetic resins, the disinfection of drinking water and photolithography.
literature
- Joseph C. Pole: The quartz lamp, its development and its current status. Springer, Berlin 1914.