UV curing sensor XT for high irradiance and process temperatures
The UV curing sensors XT measure irradiance and dose directly in the UV curing process – up to 50,000 mW/cm² and at operating temperatures of up to 150 °C. This is made possible by separating light collection from evaluation: the sensor head guides the light through a light guide into the calibrated sensor electronics in the handpiece. Two designs cover spot bonding as well as measurements in places that are difficult to access.
For adhesive bonding and curing through UV radiation, LED spotlights and gas discharge lamps with liquid light guides, whose high irradiance enables curing and polymerization within seconds, are used.
Exact measurements for monitoring the irradiance and dose are required for process control. Here, the UV sensor is exposed to the high irradiances and temperatures, which could lead to an impairment of the measurement results. The sensor series XT („eXtrem Temperature“) has been developed for this critical application. The XT sensors are compact and thus flexibly usable where needed.
The XT sensor has an excellent cosine correction, and the calibrated sensor electronics are integrated in the handpiece. That way, just like with all our high-quality radiometers, several sensors can be connected to one hand-held meter.
For your application you can select between two sensor types. The XTR guides the light through a stainless steel rod into the handpiece and is quick and easy to use. Due to the distance between the sensor head and the handpiece, the user is protected from the radiation!
In the XTF, the sensor head is connected with the flexible light guide in order to enable measurements in places that are difficult to access. Both sensors have a height of 10 mm without any impairment of the measuring precision.
The diameter of the XTR and XTF sensors is 40 mm. By the way, sensor and handpiece are flat so that even here the measurement is optimal and reproducible. XTR and XTF are thus the first choice for UV spot bonding.
The XT sensors can be connected to the RMD Pro radiometer for irradiance and dose measurements. The RMD Pro offers high resolution, a large measuring range, 8 GB of internal memory, a USB interface and an illuminated graphic display.
| Product type | UV sensor: Rod and fibre sensors for extremely high irradiance up to 50 W/cm² |
| Spectral range | UVC 200–280 nm, UVB 280–315 nm, UVA 315–400 nm, UVA+ 330–455 nm, UVBB 230–400 nm, VISB 400–480 nm, VIS 380–780 nm |
| Measuring range | 0–20 W/cm²; 0–50 W/cm² (opt.) |
| Calibration uncertainty (typ.) | 4.5–6.0 % (k = 2) |
| Output / interface | analogue sensor signal; operated with the RMD Pro radiometer (0.3 m light guide) or a spectroradiometer (1.5 m light guide) |
| Time resolution | analogue sensor signal, determined by the instrument |
| Calibration | factory calibration, ISO 17025 calibration optional (DIN EN ISO/IEC 17025:2018) |
| Standards / guidelines | no product-specific standard; calibration per DIN EN ISO/IEC 17025:2018 available |
| Suitable for | Plants, agriculture and food; UV curing and photopolymerisation; UV bonding, potting and encapsulation; Electronics and semiconductors |
| Not suitable for | spectrally resolved measurement (peak wavelength, bandwidth); irradiance above 20 W/cm² (standard range); sensor temperatures above 150 °C; use under water or under pressure |
| Datasheet revision | Rev. 2026-09-08 (E_curing-sensor-XT.pdf) |
The calibration uncertainty stated above is the expanded uncertainty of the calibration (k = 2, confidence level approx. 95 %) and applies to the calibration source and the calibration conditions. In use the measurement uncertainty is larger: spectral mismatch at the source actually used, the sensor temperature, ageing since calibration as well as distance and alignment to the source are added to it. How these combine into an uncertainty budget is explained under Measurement uncertainty in UV measurement.
Calibration
For precise measurements, we calibrate the sensors to the process light source or the used LED wavelength. For this, more than 20 radiation sources are available in our accredited laboratory. Of course, all our sensors are factory-calibrated, long-term stable and precise upon delivery. Optionally we deliver the XT sensors with an ISO 17025 calibration.
View the XT sensors as a 3D model
Look at both designs from every side, rotate and zoom – directly in your browser.
The XTF and XTR UV curing sensors can be viewed from all sides in the 3D product viewer – true to the original, generated from the CAD design data. Comparing both designs directly makes it easier to choose the right one for the installation situation.
Specifications of XT series UV curing sensors
| Operation temperature | 0 to 150 °C |
| Storage temperature | -10 to 150 °C |
| Humidity | < 80% non-condensing |
| Light guide, for radiometer | 0,3 m |
| Cable length, for radiometer | 2 m |
| Light guide, for spectroradiometer | 1,5 m |
| Measurement range | 0–20 W/cm² (standard) |
| 0–50 W/cm² (opt. for RMD) | |
| Resolution | 0,001 mW/cm² |
Frequently asked questions: UV curing sensors XT
The XT sensors are designed for the high irradiance of UV curing systems and measure up to 20 W/cm² as standard; 50 W/cm² is available as an option. This allows UV LED lamps and spot light sources to be measured directly in the focus, where classic radiometer sensors with 1–10 W/cm² saturate. The RMD Pro serves as the readout instrument and records irradiance and dose.
The XTR is a rigid stainless-steel rod, the XTF a flexible light guide. Both carry the radiation from the hot measuring point to the electronics, which stays outside the heat zone. The rigid rod suits reproducible positioning in machines and test rigs, the flexible light guide curved paths and tight spaces. The measuring surface is at the tip in each case; the spectral ranges UVC, UVB, UVA, UVA+, UVBB, VISB and VIS can be chosen for both.
Yes. Since only the rod or light guide reaches into the radiation zone, the electronics stay at their operating temperature, while the tip tolerates considerably higher temperatures than a complete sensor head; the tip is rated for up to 150 °C. For permanent measurement inside the machine, however, the XT is a test instrument and not a permanently installed process sensor; inline sensors FLT or PLC sensors with 4–20 mA are intended for that.
The calibration certificate states the expanded calibration uncertainty with k = 2; for the UV curing sensors XT it is typically 4.5–6.0 %. In use the measurement uncertainty is larger, because spectral mismatch at the source actually used, sensor temperature, ageing and measuring geometry are added to it. How these combine into an uncertainty budget is explained under Measurement uncertainty in UV measurement.
Sensor for UV curing at high process temperature
A sensor for UV curing sits where the radiation is strongest – and therefore where it gets hottest. The XT sensors are rated for process temperatures up to 150 °C and measure up to 50,000 mW/cm².
The combination is the point: a sensor that withstands the irradiance but not the temperature drifts – and the reading falls while the process runs unchanged.
Order numbers, scope of delivery, accessories and versions
| Spectral range | Order number |
|---|---|
| UVC | 810641 |
| UVB | 810642 |
| UVA | 810652 |
| UVA+ | 810650 |
| UVBB (broadband) | 810640 |
| VISB | 810651 |
| LUX | 810646 |
Scope of delivery: the XT curing sensor with its factory calibration certificate. Please state the spectral range, the measuring range and the instrument with your order.
| Designation | Order number |
|---|---|
| Transport case | 921002 |
| UV protective goggles | 918800 |
| Service | Order number |
|---|---|
| Factory calibration | 710000 |
| ISO 17025 calibration | 17025 |
Accredited calibration to ISO/IEC 17025 in our own calibration laboratory. The factory calibration is included in the scope of delivery.
