What is UV radiation?
Ultraviolet radiation is electromagnetic waves with a wavelength of 100 to 380 nm or a frequency of over 789 THz. The energy of a single light quantum is about 3.26 eV. Ultraviolet radiation is not visible.

It belongs to the group of optical wavelengths, which is why the term “UV light” is often used, which is not quite correct. UV radiation can be refracted, reflected, diffracted and absorbed like light of other wavelengths or infrared radiation – however, the reflection behaviour with regard to the choice of material for the reflector cannot be compared with that of the visible range. Ultraviolet radiation can be made indirectly visible by luminescence excitation (see analytical instruments / Wood Light).

What does UV-A, UV-B and UV-C mean and what is the difference?
Ultraviolet radiation was divided into several groups. These groups have different biological effects and technical applications. The following diagram shows in which range of the electromagnetic spectrum UV radiation is found. The entire UV range is defined as 400 – 10 nm. Here, the energy of the light quanta is inversely proportional to the wavelength (the shorter the wavelength, the more energetic the radiation).

Who discovered UV radiation?
As early as 1878 two researchers (A. Downes & T. P. Blunt) discovered the causal relationship between UV radiation and the growth of microorganisms. The aim was to prove that micro-organisms do not multiply without solar radiation. A long time later it was found that short-wave UV radiation in the UV-C range has a decontaminating effect. In the 1960s, with the decoding and research of DNA, this was only fully understood.

Who produced the first UV radiation source?

Richard Küch was the first person to melt quartz glass, the basis for UV radiation sources, in 1890 and founded the “Heraeus Quarzschmelze”. He developed the first quartz lamp in 1904, laying the foundation for the lamp technology that is still used today. The first quartz lamp, whose UV light yield almost corresponded to the spectrum of the sun, was created under the roof of the then “Original Hanau”.

With the development of low-pressure mercury vapour radiation sources, it was possible, for example, to artificially produce UV-C radiation with a disinfection effect. In the course of time, more and more applications for the technically generated UV radiation were discovered and made industrially usable. As a result, new applications are still being found and brought to market maturity year after year.

We accompany you on this way with competence and expertise.

Why disinfects ultraviolet?
All microorganisms contain, among other things, nucleic acid (the DNA and RNA), which contains the genetic information of the cell. Because the nucleic acids absorb the incident radiation energy, a photochemical process is triggered which damages the reproduction apparatus of microorganisms and inactivates germs. This takes place, among other things, via a frequently occurring “dimer bond” of the thymine building blocks. This happens in a fraction of a second..

No resistance against UV possible!

Popularly said: bacteria, viruses, yeast and moulds have no chance against ultraviolet. Because additional resistance cannot be acquired according to scientific knowledge. Most pathogenic germs are even particularly sensitive to UV rays. This is an important advantage of physical disinfection, as it also works, for example, when germs have already acquired resistance to conventional disinfection measures (alcohol, antibiotics, etc.). At this point we would like to point out the MRSA problem, with which many medical facilities have reached the limits of the disinfection and prevention measures practiced so far.

This circumstance of physical disinfection works for all microorganisms, no matter whether it is about frequently occurring E.Coli bacteria, vecal germs, TBC, SARS, anthrax or legionella. However, a sufficient UV dose is essential – and requires appropriate equipment development.

No confusion with gamma- and X-rays
As invisible radiation, sunlight also contains ultraviolet and this, like visible light, only works on the surface. Therefore it is also called “soft” radiation. In contrast, there are many short-wave emitters (below 100 nm), such as “hard” X-rays and gamma rays. “Hard” because they can penetrate solid matter and cause severe damage to the human organism. This is impossible with ultraviolet. For this reason there can be no confusion or comparison.

Every UV radiation source has an electrical power consumption, part of which is emitted in the UV-C range. 90% of the radiation emitted in the UV-C range is generated at 254 nm, the wavelength effective for disinfection. This is called radiation power. The radiant power is therefore the energy emitted per unit time by the radiator.

The irradiance or also called intensity (µW or mW) is the radiated power per unit area (cm²). Decisive for its level is the optimal utilization of the radiator installed in the device as well as the distance to the item to be sterilized.

If the irradiance/intensity is multiplied by time (s), the UV dose/irradiation dose is: UV dose (mWs/cm²) = intensity (mW/cm²) x time (s)

The higher the radiation power and the longer the irradiation time, the greater the disinfecting effect.

For almost all microorganisms, the “lethal dose” of UV-C radiation is known, from which the cell loses its reproductive property, is inactivated and no self-repair mechanisms can be activated. Due to the cell structure, the lethal dose varies. Pathogenic germs and yeasts are extremely sensitive to UV-C. Some mould spores require a higher UV dose. If necessary, this must be taken into account in the design.

The basis of UV disinfection is the design of the disinfection device or the selection of a suitable radiation source. At the end of the lamp’s service life, a sufficiently high UV dose must be available to ensure an appropriate disinfection performance within the defined irradiation time. The lethal dose varies depending on the micro-organism and cell structure / cell type. Pathogenic germs are very sensitive to UV-C and are inactivated very quickly. Mould spores require a higher UV dose. In practice, e.g. sealing films for yoghurt pots achieve a germ reduction of 99.5 % to 99.9 % within 2 seconds (see Fraunhofer test report for BlueLight modules).