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extralight/ sun substitutes
following the light
One of the first successful medical applications of artificial sunlight came from the Danish scientist Niels Finsen who, in 1893 already,
used red light for the treatment of smallpox. In 1895 he also successfully used ultraviolet radiation for the treatment of lupus vulgaris, a form of skin-tuberculosis. The UV-radiation was generated with help of a powerful carbon-arc lamp. The ultraviolet part of this radiation mainly consisted of UV-A which was concentrated with lenses while the warmth caused by the infrared part of the radiation was lead away to allow for local treatment of sensitive parts of the face. Finsen was awarded a Nobel Prize in Medicine for his work in 1903
and his ultraviolet device became known as the Finsen lamp. An early patent on a similar application of artificial sunlight for therapeutic usage was granted in 1898 to Dr. Willibald Gebhardt from Berlin. This patent concerned a local treatment with concentrated light from again a carbon-arc lamp. The application of Dr. Gebhardt's device was, similar to that of
the Finsen lamp, aimed at the treatment of local skin diseases. They marked the first steps in the development of a broad range of sunlight replacements for therapeutic purposes. With the introduction of electric lighting also the use of light baths became popular, cabinets that were fitted with arc-lamps or incandescent lamps and in which one could sit or lay down. Where the effect of a light bath was based on a rise of the body temperature as a whole in order to stimulate the metabolism in general.
from arc-lamp to sun-lamp
Where the arc-lamp became the first electric light source for therapeutic use, the gas discharge lamp would become the most important one. The first usable gas discharge lamps capable for medical treatment appeared at the beginning of the 20th century. They consisted of low-pressure mercury vapour discharge lamps that, due to their greenish-blue colour and low light production, where of little use for lighting appliances. The lamps produced a
relatively high amount of ultraviolet radiation however, which made them suitable for the treatment of certain skin diseases. From 1908 on, high-pressure mercury vapour discharge lamps with a much higher light production appeared on the market. In order to withstand the high temperature and pressure these lamps were made of quartz glass. Unfortunately this glass passed a great
deal of the ultraviolet radiation. For domestic appliances this happened to be a drawback but it made the lamps extremely suitable for the manufacturing of sun-lamps. The UV-B production of mercury vapour discharge lamps exceeded that of carbon-arc lamp significantly, allowing for new and more effective methods of treatment. In particular for the treatment of rachitis or rickets the high-pressure discharge lamps have proven to be very effective. Until the first decades of the 20th century rachitis formed a wide spread disease, caused by a lack of vitamin D. A regular consumption of a limited quantity of cod-liver oil had proven to be effective already since 1918 although vitamin D as the crucial ingredient would only be identified in 1922. In 1919 de German
The classification of sun substitutes on the following sub-pages has been made along the line of the therapeutic applications they
this context is both used for devices with an ultraviolet source only as well as for devices with a combination of an ultraviolet- and an infrared source. Formally a blended lamp is a combined infrared- and ultraviolet device too. Since it is very rare however to find blended lamps with an independently switchable infrared- and ultraviolet source (but they
were designed for. Light sources, infrared radiators and ultraviolet radiators intended for respectively light-, infrared- and ultraviolet therapies. Sun substitutes applicable for more than one of these main treatment categories will therefore be described on the appropriate sub-page with the focus on the concerning application. In the sun gallery in addition you will find a separate fourth entry for devices with both an infrared- and an ultraviolet source because these devices in most cases can be used in several ways. As an infrared radiator,
as a combined infrared- and ultraviolet radiator or, when the ultraviolet source is not regulated by the infrared source, as an ultraviolet radiator. Please notice that the indication "sun-lamp" in
exist!), devices with blended lamps on this site are placed amidst the ultraviolet radiators.
from doctor to patient
Although the first sun substitutes basically consisted of modified light sources, the armatures they were fitted in were optimised for their therapeutic use from the beginning on. The reason for this may be found in the fact that the first devices were intended for professional medical applications only. With some minor adaptations the scope of these
from remedy to luxury
The medical application of infrared- and ultraviolet radiation started shortly before the Great War and lasted until the end of WWII. From then on heat-lamps and sun-lamps conquered the consumer market at an ever-growing rate and especially between 1960 en 1980 the lamps became very popular. After that period the popularity of the 'table lamp'
decreased somewhat, probably due to the increasing interest in short vacation trips to more sunny areas in favour of sun simulations in the living room. In addition to sun vacations more advanced sun substitutes in the form of infrared cabins and solaria still fulfil an important role in those geographical areas were unhindered sunshine is not always evident.
later on. The most evident adaptation for domestic use was the design of tabletop models were the professional variant more often was designed to be mounted on a standard. Use of material and design was only later on optimised for domestic use, which started a market development separated from the medical product lines.
professional products was extended for self-medication purposes
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the heat of a sun-lamp
Apart from ultraviolet radiation, a mercury vapour discharge lamp also produces light and infrared radiation but comparatively less then the sun itself. For that reason a sun-lamp is often fitted with an additional infrared source in order to obtain a better
approximation of natural sunlight. In many applications it is possible to switch the ultraviolet- and infrared sources on and off independently from each other, unless the infrared source has a function as a serial ballast for the ultraviolet source. Other than incandescent lamps whose temperature coefficient is positive, arc- and gas discharge lamps have a negative temperature coefficient that makes the current through the device to increase when temperature rises. This increased current will rise the temperature any further and
the process will finally make the lamp burn or melt. To avoid this, the electric current through the arc- or discharge lamp has to be limited and it is mostly an inductive or resistive element that is used to do the job. The serial ballast will produce a certain amount
of heat itself and it is for efficiency reasons that this heat is often used to contribute to the total radiation pattern of the sun-lamp. Since in such a configuration the two radiators have to be connected in series the ultraviolet radiator as a consequence will always be active together with the infrared radiator. The infrared radiator, which is stable from itself, can often still be used separately,
assuming the electrical circuits of the sun-lamp support this function. From a medical point of view however, the quality of such an infrared device is usually less than that of a dedicated infrared source. Due to the savings in both cost and weight these serial configurations have become very popular though.
scientist K. Huldschinsky was the first who succeeded in curing children from rachitis by treating them with artificial generated ultraviolet radiation. From 1920 on, milk that was enriched with vitamin D by exposing it to ultraviolet radiation from strong high-pressure mercury vapour discharge lamps formed a more tasteful alternative for the cod-liver oil. For they who could afford it, a more effective direct treatment of the skin with ultraviolet radiation remained the favourite. Now a days our circumstances for living and our eating habits guarantee the consumption
of the necessary quantities of vitamin D but especially during the winter period an additional exposure to some ultraviolet radiation can still be in favour of our wellbeing.
Until than only petroleum-
or gas burners had been available as a source of therapeutic heating for domestic use. Around 1920 electric heating elements became available for this purpose. Early infrared radiators for therapeutic use were in fact less more than optimised electric heaters with a high yield of (for therapeutic use undesirable) long wave infrared radiation. Distinction between therapeutic
infrared radiators and
'ordinary' heaters is therefore often difficult, especially when further documentation is not available. The further development of artificial sunlight for therapeutic appliances is closely connected to the development of electric light sources for domestic use. The search for good and cheap manufacturable light sources was driven by an immense potential market and unleashed an effort that would never have been released by medical needs only. The demand from a therapeutic point of view was there, the
effort to open a much broader market created the possibilities to fill that demand.