UV irradiance and UV dose: what is actually calibrated?
UV curing and disinfection processes often use the terms intensity and dose interchangeably. In metrology, they describe different quantities. The distinction matters when selecting a calibration method, reporting units and interpreting process limits.
Two quantities, two different questions
| Quantity | Meaning | Common units |
|---|---|---|
| Irradiance (E) | Radiant power incident per unit area at the detector plane | W/m², mW/cm² |
| Radiant exposure (H), often called UV dose | Time integral of irradiance over an exposure | J/m², mJ/cm² |
For a constant irradiance, H = E × t. For a changing source, the correct expression is H = ∫E(t)dt. As a simple example, 10 mW/cm² sustained for 5 seconds corresponds to 50 mJ/cm². A radiometer with an integrating function may report both peak irradiance and accumulated exposure, but those functions do not necessarily share the same calibration procedure.
Why wavelength matters
UV meters typically use a filter and detector with a wavelength-dependent spectral responsivity. A meter calibrated with one lamp spectrum may respond differently to a narrowband UV LED or a different mercury-lamp emission spectrum. Consequently, a nominal UVA, UVB, UVC or UVV label is not a sufficient description of the measurement conditions. Supply the intended source type, dominant wavelength or spectrum, and the sensor/filter designation when requesting calibration.
Geometry and the instrument configuration
Detector orientation, working distance, aperture, spatial uniformity, angular response and the physical dimensions of the UV source may influence the measurement result. A detachable probe must be identified together with its display unit. For conveyor-type UV integrators, the exposure profile, sample interval and integration algorithm may also be relevant.
What should a quotation request include?
- Manufacturer, model and serial number of the readout and sensor.
- Source technology: UV LED, mercury lamp, excimer or other.
- Target wavelength(s), measurement range and reporting units.
- Whether irradiance, integrated radiant exposure or both are required.
- Any process acceptance limit and required calibration uncertainty.
- Whether an accredited certificate is mandatory for the intended measurement quantity.
Accreditation note: ISO/IEC 17025 accreditation does not automatically cover every UV band, sensor, dose function or measurement range. The current laboratory scope and the feasibility of the requested configuration must be checked before an accredited service is confirmed.
Next steps
Explore UV dose meter calibration, UV LED radiometer calibration, or contact LightingLab with your instrument details.