A critical quality feature of UV curing processes is the control of the UV dose within the wavelength range required of the particular photoinitiators used. Dose is measured in J/cm² and is the product of UV intensity and time of exposure (W/cm² x seconds). UV intensity, also referred to as irradiance, is measured by UV radiometers in W/cm². Therefore, suitable UV radiometers permit the correct setting of irradiance levels and irradiation times as well as enabling periodic adjustments to compensate for the aging effects of the UV lamps and UV LEDs.
UV radiometers suitable for UV curing must meet important requirements:
* Flat design for measurements near the reference plane
* Sufficient measuring range for the very high irradiance in the UV curing processes
* UV radiation resistance for long-term stability
* Temperature resistance during the measurement
* Safe handling to protect the user from hazardous UV radiation
* Traceable calibrations
UV radiometers are available in two different technologies:
* Broadband UV radiometers are most suited for consistency measurements of the UV irradiance within a defined spectral range. They are inexpensive and very easy to use.
* UV spectroradiometers are used when different UV lamps or photoinitiators are in use. They are ideal for process development and manufacturing preparation.
UV radiometers for measuring the irradiance (mW / cm²) and dose (J / cm²) of mercury vapor lamps and UV LEDs.
|Model||Image||Spectral function||Wavelength range / nm||Entrance optic||Typ. Range Minimum SNR=50 100ms integration||Typ. Range Maximum||Remark|
|LED λ's: 365, 375, 385, 395, 405 & 430 nm||350 - 450||Diffuser 9 mm Ø||1 mW/cm²||40 W/cm²||UV radiometer for routine measurements of high power UV LEDs. Multiple calibrations at LED wavelengths. Rigid light guide provides 25cm sensor to handle distance for operator safety.|
|Narrowband UV-A||365 nm peak||Diffuser 9 mm Ø||0.02 mW/cm²||40 W/cm²||UV radiometer for routine measurements of UV-A narrow band (365nm) high power UV lamps. Rigid light guide provides 25cm sensor to handle distance for operator safety.|
|UV-A, UV-B and Blue light||250 - 485||Diffuser 9 mm Ø||< 1 mW/cm²||40 W/cm²||Range of UV curing irradiance detectors for use with all common types of discharge lamps and UV LEDs covering UV-A, blue light and UV-B spectral ranges. E.g. for use with X1-1 handheld meter.|
|Model||Image||Entrance Optic||Wavelength range /nm||Optical Bandwidth||Spectral responsivity min.||Spectral Responsivity Max.||Remark|
|BTS256-UV-1||Diffuser 9 mm Ø on 25cm rigid guide||225 - 525||2.8 nm||0.01 W/ (m2 nm)||1000 W/ (m2 nm)||Ultra-thin sensor (8mm) with 25cm rigid guide connection to spectroradiometer. Typical measurement times: 360 nm LED with 50 mW/cm² - 100 ms 460 nm LED with 50 mW/cm² - 45 ms|
|BTS256-UV-2||Integrated Diffuser 10 mm Ø||200 - 525||2.8 nm||0.01 W / (m2 nm)||> 1000 W / (m2 nm)||Integrated sensor permits use on conveyor systems. 12mm device thickness. Typical measurement times: 360 nm LED with 50 mW/cm² - 65 ms 460 nm LED with 50 mW/cm² - 35 ms|