RM-12 – irradiance and illuminance at low cost
The UV meter RM-12 is a battery-powered hand-held instrument for measuring irradiance and illuminance. The measuring range covers 0–199 mW/cm², optionally 0–1999 mW/cm², at a resolution of 0.01 mW/cm²; illuminance is recorded up to 200,000 lx. Through the M12 connector, sensors for spectral ranges from UVC to VIS can be exchanged, and a 9 V battery lasts for about 50 operating hours.
Due to the sensor-integrated electronics, different sensors for UV and visible spectral ranges can be measured with the respective sensors. Sensors evaluating biological effects of irradiation are also available.
The integrated diffuser serves to provide the cosine correction that is necessary with non-perpendicular irradiation. The sensors are calibrated with traceability to the PTB; after being calibrated, they are supplied with a factory calibration certificate. Repair and spare parts service is, of course, available for many years.
The sensors can be supplied with different measuring ranges.
Applications:
- Measurement of UV lamps, UV LEDs, and light sources
- Control of UV irradiation
- Photometric measurements
| Product type | UV meter: Battery-powered entry-level handheld UV radiometer for irradiance and illuminance |
| Spectral range | depending on the interchangeable sensor: UVC 200–280 nm, UVB 280–315 nm, UVA 315–400 nm, UVA+ 330–455 nm, UVBB 230–400 nm, VISB 400–480 nm, LUX 380–780 nm, V(λ) |
| Measuring range | 0–199 mW/cm², optionally 0–1999 mW/cm² |
| Calibration uncertainty (typ.) | 4.5–6.0 % (k = 2) |
| Output / interface | Sensor connector: M12 (5-pin); signal voltage: 0–2 V |
| Time resolution | analogue sensor signal, determined by the instrument |
| Calibration | factory calibration, recalibratable |
| Standards / guidelines | no product-specific standard; calibration per DIN EN ISO/IEC 17025:2018 available |
| Suitable for | UV curing and photopolymerisation; Fluorescent penetrant testing and inspection; Occupational safety and photobiological safety |
| Not suitable for | spectrally resolved measurement (peak wavelength, bandwidth); irradiance above 199 mW/cm² (standard range); sensor temperatures above 40 °C; use under water or under pressure |
| Datasheet revision | Rev. 2026-09-08 (e_rm12.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.
Technical data UV meter RM-12
| Measuring range | 0–199 mW/cm², optionally 0–1999 mW/cm² |
| Resolution | 0.01 mW/cm², optionally 0.1 mW/cm² |
| Illuminance, measuring range | 0–200,000 lx |
| Illuminance, resolution | 10 lx |
| Dimensions | 160 × 85 × 35 mm |
| Weight | 300 g |
| Power supply | 9 V |
| Battery lifetime | about 50 h |
| Operating temperature | 0 to 40 °C |
| Storage temperature | -10 to 40 °C |
| Humidity | below 80 %, non-condensing |
| Sensor connector | M12 (5-pole) |
Buying a UV meter: when the RM-12 is enough
The RM-12 is the entry-level instrument of the range – a battery-powered hand-held UV radiometer measuring irradiance and illuminance, from UVC into the visible depending on the interchangeable sensor. For most recurring checks that is exactly enough.
It is enough where one figure at one measuring point is needed: checking the lamp after a change, checking the booth against the standard, documenting irradiance at the workpiece. The instrument is recalibratable, its calibration traceable to the PTB – and it is inexpensive enough to sit in every booth rather than once in the plant.
It is not enough for spectrally resolved measurement – it cannot determine the peak wavelength or bandwidth of a UV LED; the UVpad and UVpad E do that. Nor above 199 mW/cm² in the standard range, at sensor temperatures above 40 °C, or under water. High-power processes are measured by the RMD Pro, process temperatures up to 150 °C by the XT sensors, and in water the UVx-SE and UVC-SE take over.
Which UVC irradiance levels were measured in studies, and when an RMD is the better choice for UVC, is shown in the overview UVC meter.
Frequently asked questions: RM-12
No. The RM-12 displays the current irradiance in mW/cm² and the illuminance in lx, but does not integrate over time and does not store readings. Anyone who needs the dose in J/cm² or a time profile uses the RMD Pro (dose, 8 GB memory) or the curelog for conveyor systems. The RM-12 remains the low-cost instrument for check measurements, lamp comparisons and safety checks with the same sensor spectral ranges.
The standard measuring range is 0–199 mW/cm² with a resolution of 0.01 mW/cm²; optionally 0–1999 mW/cm² with 0.1 mW/cm² resolution is available for UV LED lamps and spot light sources. Illuminance is displayed up to 200,000 lx with 10 lx resolution. The range is determined by the connected sensor; the expected irradiance of the system should therefore be stated when ordering.
The RM-12 is powered by a 9 V block battery and runs for about 50 hours on it. It weighs 300 g at 160 × 85 × 35 mm and is designed for 0–40 °C operating temperature. Because sensor and instrument are calibrated separately, the same display unit can be used with several sensors in UVC, UVB, UVA, UVA+, UVBB, VISB and LUX; the connection is made via the five-pin M12 socket.
The calibration certificate states the expanded calibration uncertainty with k = 2; for the RM-12 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.
The RM-12 is used for dose control and for monitoring irradiation experiments. Most recently published:
- The energy saving potential of a novel smart photochromic glass film for a model office across various European climates — Kragt, A. J. J.; van der Burgt, J. S. · Glass Structures & Engineering · 2026
- Differential effects of UVA, UVB, and PAR on photosynthetic efficiency in red algae: Gracilaria dentata, Hypnea musciformis and Centroceras clavulatum — 2025
- Smart photochromic glass films: the evolution in glass performance — Kragt, A. J.; Burgt, J. S. v. d. · 2025
- A facile strategy to determine photon flux and effective optical path length in intensified continuous-flow photoreactors — Zondag, S.; Schuurmans, J.; Chaudhuri, A. et al. · 2024
- Comparison of the Effects of UV-C Light in the Form of Flash or Continuous Exposure: A Transcriptomic Analysis on Arabidopsis thaliana L. — Jazayeri, S. M.; Aarrouf, J.; Urban, L. et al. · International Journal of Molecular Sciences · 2024
The details come from Crossref. Authorship and content rest with the respective research groups.
These are the rules most often consulted in practice for radiometers and sensors — from measurement through limits to the requirements on the device:
- DIN EN ISO/IEC 17025:2018-03 — General requirements for the competence of testing and calibration laboratories
- DIN EN 62471:2009-03 — Photobiological safety of lamps and lamp systems
- DIN EN 14255-1:2005 — Measurement and assessment of personal exposure to incoherent optical radiation — Part 1: UV radiation from artificial sources in the workplace
All rules for radiometers and sensors are listed in the standards finder.
Not a normative reference. What counts is always the currently valid edition in the original text.
Order numbers, scope of delivery, accessories and versions
| Device | Order number |
|---|---|
| UV-Messgerät RM-12 | 821200 |
Scope of delivery: the RM-12 (radiometer without sensor), the manual and the battery. Please state the required sensor and the sensitivity with your order. Unless specified otherwise we supply the measuring range 0–199 mW/cm².
| Spectral range | Order number |
|---|---|
| UVC | 811010 |
| UVB | 811020 |
| UVA | 811032 |
| UVA+ | 811047 |
| UVBB (broadband) | 811012 |
| VISB | 811043 |
| LUX | 811090 |
All the sensors listed can be operated on one RM-12. They are calibrated with traceability to the PTB and can be recalibrated.
| Measuring range | Note |
|---|---|
| 0–199 mW/cm² or klux | standard version |
| 0–1999 mW/cm² or klux | option -1 |
Please state the required measuring range with your order. Without a statement we supply 0–199 mW/cm².
| Service | Order number |
|---|---|
| Factory calibration | 710000 |
| ISO 17025 calibration | 17025 |
On delivery the RM-12 is already factory-calibrated. The accredited ISO 17025 calibration from our own calibration laboratory can be ordered as an option.
| Designation | Order number |
|---|---|
| Transport case | 921000 |
| UV protective goggles | 918800 |
