22IEM05 NEWSTAND - New Calibration Standards and Methods for Radiometry and Photometry After Phaseout of Incandescent Lamps

• Forschungsstelle: METAS
• Projektnummer: F-5116.30184
• Projekttitel Englisch: 22IEM05 NEWSTAND - New Calibration Standards and Methods for Radiometry and Photometry After Phaseout of Incandescent Lamps

Schlüsselwörter (Englisch)

SI-traceability, optical radiation, incandescent lamps-based transfer standards, detector-based transfer, spectral irradiance measurement, spectroradiometer calibration, quartz-tungsten-halogen (QTH) lamps

Kurzbeschreibung (Englisch)

The SI-traceability of spectroradiometric measurements of optical radiation in a multitude of applications (monitoring essential climate variables, industrial processes, lighting, healthcare, occupational safety, photovoltaic energy generation, etc.) has been realised by means of incandescent lamps-based transfer standards. The availability of the lamps, though, is diminishing due to a production phaseout of incandescent lighting products. The project aims to provide adequate and affordable replacement sources and alternative procedures for a detector-based transfer of the spectral irradiance unit in the ultraviolet-visible-near infrared spectral range and to establish an integrated European metrology infrastructure around this key radiometric unit. 

Accurate knowledge of spectral irradiance of optical radiation emitted by artificial and natural light sources is essential in various fields of industrial (UV-curing, disinfection, photovoltaic equipment, general and horticultural lighting, etc.), environmental (solar radiation, Essential Climate Variables (ECVs), etc.), medical (sun beds, photobiological treatment, etc.), or scientific (analytical spectroscopy, plasma, etc.) applications. The range of applications for spectral irradiance measurements has grown dramatically during the last couple of decades due to the market introduction of affordable new-technology spectroradiometers based on array detectors and digital capabilities for in situ processing of the spectral data. The routine availability of the spectral characteristics of optical radiation sources is seen as one of the technological enablers for higher-quality products, information, and services.

For the calibration of spectroradiometers, incandescent lamp-based transfer standards have been used for decades. Selected quartz-tungsten-halogen (QTH) lamps of certain types have been applied to disseminate the spectral irradiance unit in the spectral range from 250 nm to 2500 nm. However, the market availability of such lamps and their applicability for this metrological purpose is diminishing due to the production phaseout following the ban of the incandescent lighting by the EU Commission in 2009 and by a technology change to solid-state-lighting (SSL) products. Thus, alternative transfer standards built on new-technology sources with preferably smooth spectra throughout the UV-VIS-NIR spectral range and/or detector-based dissemination methods are urgently needed. The urgent needs for the research activities addressed by the project are explicitly described in the orientation papers by two major stakeholders, European Association of National Metrology Institutes (EURAMET) Technical Committee for Photometry and Radiometry (TC-PR) as well as Division 2 of the International Commission on Illumination (CIE). The need for new standards triggered by the transition to solid-state lighting has been expressed also in the research strategy papers by the Consultative Committee for Photometry and Radiometry (CCPR) of the International Committee for Weights and Measures (CIPM), EURAMET, and CIE.

Projektziele (Englisch)

The overall goal of this project is to assure SI-traceable measurements of spectral irradiance of natural and artificial sources of optical radiation and to develop the metrological infrastructure required for these measurements after the technology change-driven phaseout of the incandescent lamps currently used as transfer standards. The specific objectives of the project are:

1. To develop new standard sources for spectral irradiance in the ultraviolet-visible-near infrared (UV-VIS-NIR) spectral ranges, built on new-technology products, to replace current transfer standards that are based on incandescent lamps. The specific requirements for the spectral irradiance of the new standard sources are: i) well-defined and fit-for-purpose spectral and geometric properties, ii) long-term stability, iii) reproducibility, iv) robustness, and v) compatibility with existing calibration facilities. The new standard sources should enable dissemination of the spectral irradiance unit with transfer uncertainties as low as 0.5 % (k = 2).
2. To develop novel methods for enabling detector-based traceability of spectral irradiance measurements as an alternative to the incandescent lamps-based dissemination of the unit. This should involve i) the definition of the minimum requirements for relevant properties of (array) spectroradiometers to be suitable as transfer standards, ii) the development of procedures for their calibration that enable traceable measurements at end-user sites, and iii) the determination of uncertainties associated with the new traceability methods for spectral irradiance.
3. To demonstrate the metrological applicability of the new standard sources and methods, developed in objectives 1 and 2, in spectroradiometric applications involving spectral irradiance measurements in at least 3 end-user sites with total uncertainties as low as 1 % (k = 2).
4. To develop good practice guidelines for using the new standard sources and calibration procedures, as well as to implement the measurement methods and devices developed by the project.
5. To demonstrate the establishment of an integrated European metrology infrastructure and to facilitate the take up of the technology and measurement infrastructure developed in the project by the measurement supply chain (calibration and testing laboratories), standards developing organisations (CIE Division 2), technical committees (EURAMET TC-PR, CCPR) and end users (manufacturers and users of spectroradiometers).