X1-4

UV radiation is one of the most prevalent cancer risk factors. Because of this, federal lawmakers are trying to reduce the risk from artificial UV radiation with the UV Protection Directive. For sun tanning beds that emit UV radiation, this is achieved by a limit on the maximum UV output. 

In order to provide the responsible committees with a mobile instrument to measure UV radiation in accordance with the UV Protection Directive, Gigahertz-Optik GmbH has developed the X1₄ Broadband Radiometer. 

The UV radiometer‘s UV erythema detector head sets itself apart from others thanks to the fact that it features two UV radiation detectors. Separating the UVA and UVB spectral ranges between two radiation detectors reduces the crosstalk between the long-wavelength UVA and short-wavelength UVB spectral ranges. This design principle offers a greatly reduced measurement uncertainty compared to UV erythema measurement detectors with only one UV radiation detector. 

The spectral sensitivity of the two UV radiation detectors take into account the UV erythema actinic function. Therefore the sum signal of the two UV radiation detector forms the effective UV erythemal irradiance. Additionally, both signals can be displayed separately in order to depict the ratio of UVB to UVA radiation. 

In addition to the verification of the UV erythemal irradiance, the UV Protection Directive conform inspection of UV sun tanning beds also requires verification of the UVC irradiance in the spectral range from 200 to 280nm. The UVC radiation must be less than the limit of 0.003 W/m². The UV Eythema measurement head of the X1₄ includes a separate UVC detector for this purpose. 

The X1₄ Erythema UV meter and the XD-45-ERYC measurement head were developed in accordance with DIN 60335-2-27 and DIN 5050-1 conform to the respective critical values.

The measurement uncertainty due to the spectral mismatching of Broadband Radiometers can be effective reduced if the spectrum of the measured lamp is known. The X14 UV Erythema Broadband Radiometer includes a database of common spectrums of artificial UV lamps, technical UV radiators, and the sun spectrum at various zenith angles. The measurement uncertainty of +/- 25% without knowledge of the lamp’s spectrum can be reduced to +/- 6.5% when the spectrum is known. 

A basic prerequisite for the accurate measurement of UV irradiance of extensive UV emitters is that the UV meter has a cosine-corrected field of view. The UV Protection Directive refers to the DIN 5050-1 that dictates an f2 error of less than 0.06. 

Only three buttons and a clearly structured menu make the meter easy to operate. The UV radiation detector head is separate from the device and is connected to the device using a 2m cable. There is a mounting point for a tripod on the measurement head. 

The X1₄ UV meter includes a USB interface to enable operation with a computer. During USB operation the device is supplied with power through the USB interface. 

Threshold values from the UV Protection Directive

Relevant norms and regulations: UV Protection Directive, DIN EN 60335-2-27 (VDE 0700-27):2009-04, DIN 5050-1:2010-01

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Threshold values irradiance
UV Protection Directive	250 nm - 400 nm 0.3 W/m²eff 200 nm - 280 nm 0.003 W/m²
60335-2-27	250 nm - 320 nm 0.15 W/m²eff 320 nm - 400 nm 0.15 W/m²eff
5050-1	No threshold value defined for UVC 200 nm - 290 nm

Threshold values spectral correction
UV Protection Directive	Consult 60335-2-27 and 5050-1
60335-2-27	No value for spectral correction
5050-1	f1< 0.2 for broadband radiometer without specification of reference spectrum

Threshold value cosine correction
UV Protection Directive	Consult 60335-2-27and 5050-1
60335-2-27	No specifications for difference to cosine
5050-1	f2 <0 .06 for broadband radiometer

Threshold value temperature coefficient
UV Protection Directive	Consult 60335-2-27and 5050-1
60335-2-27	Measurement at 20 °C ± 5 °C ambient temperature
5050-1	0.005 K-1 (10 °C - 50 °C)

Burn-in period of UV Emitters
UV Protection Directive	Consult 60335-2-27and 5050-1
60335-2-27	Half of the maximum exposure time
5050-1	At least 15min and fluctuations less than ± 5 %