The new X1-1-UV-3727 radiometer from Gigahertz-Optik is designed to accurately measure the far-UVC irradiance or dose produced by 222-nm excimer lamps. This is in addition to the measurement of other germicidal UV source types including low pressure Hg lamps and UV LEDs. Each meter has a wide dynamic range and is supplied with a traceable calibration certificate. Far-UVC radiation, such as the 222 nm produced by Kr-Cl excimer lamps, has been the subject of many studies and is known to be effective against a wide range of pathogens. Significantly, it is also thought to offer less photobiological hazard, because far-UVC light cannot penetrate human skin as deeply as the longer wavelength UV radiation produced by low pressure Hg lamps and UVC LEDs.
The X-1-1-UV-3727 radiometer measures UV-C irradiance over a very wide dynamic range from 0.002 µW cm–2 to 1000 µW cm–2 which permits the investigation of both germicidal efficacy as well as hazard. It is supplied with calibrations at 222 nm for excimer lamps, 254 nm for low pressure Hg lamps and wavelength dependent calibration factors given in 5 nm increments 250 nm to 300 nm for UV LEDs. The detector’s flat spectral responsivity ensures lowest measurement uncertainty irrespective of the precise wavelength of UV LEDs which inevitably varies according to operating conditions and manufacturing tolerances.
The handheld meter provides a real time display of irradiance (mW cm–2) or dose (mJ cm–2) and includes a peak-hold function. The device may also be operated via its USB interface with optional S-X1 software. To correctly measure irradiance the detector’s entrance optic is a diffuser with a cosine field of view. The detector is pre-aged to significantly reduce solarisation effects that results from long term exposure to UV radiation.