The spectral distribution is a fundamental property of non-monochromatic optical radiation. It is commonly used in research and practical applications when studying how light interacts with matter and living organisms, including humans. In the field of lighting, misconceptions about the spectral distribution of light are responsible for unfounded claims, which pervade the scientific and technical communities. Starting from the definition of the spectral distribution, this paper describes the ambiguities and errors associated with a purely graphical analysis of the spectral distribution. It also emphasizes the importance of considering the particle nature of light in research involving both visual and non-visual effects, which implies using the spectral distribution expressed in the photon system of units, a system that has been seldom used in lighting research for historical reasons. The authors encourage lighting engineers and researchers to determine which system is best suited to their work and then proceed with the correct use of spectral distributions and of spectral weighting functions for applications involving optical radiation.

This contribution discusses the direct relationship of any SI unit to the defining constants. For many of the SI derived units the relationships to the defining constants are simpler than to the SI base units. Furthermore, some of the relationships directly reflect the fundamental quantum-physical effects that are exploited in the primary realisation of units. It is not the intention of this article to question the status of the seven SI base units and the distinction between the SI base units and the SI derived units, which have evolved historically and persist for pedagogical reasons, but instead to provide an alternative view of the SI. This alternative view also allows a broader and more modern presentation of metrology in general and demonstrates that, in respect of the ability to be directly realised from the defining constants, there is little practical difference between the SI base units and SI derived units.

This article describes the development of a device to investigate the non-visual responses to light: The Light-Dosimeter (lido). Its multidisciplinary team followed a user-centred approach throughout the project, that is, their design decisions focused on researchers’ and participants’ needs. Together with custom-made mountings and the software Lido Studio, the lidos provide researchers with a holistic solution to record participants’ light exposure in the near-corneal plane in laboratory settings and under real-world conditions. Validation measurements with commercial equipment were deemed satisfying, as was the combining with data from other devices. The handling of the lidos and mountings and the use of the software Lido Studio during the trial period by various researchers and participants were successful. Despite some limitations, the lidos can help advance research on the non-visual responses to light over the coming years.

In recent years, there has been a growing interest in the measurements of the bidirectional reflectance distribution function (BRDF) in industry and research and development. However, there is currently no dedicated key comparison to demonstrate the scale conformity. To date, scale conformity has been proved only for classical in-plane geometries, in comparisons between different national metrology institutes (NMIs) and designated institutes (DIs). This study aims at expanding that with nonclassical geometries, including, for the first time, to the best of our knowledge, two out-of-plane geometries. A total of four NMIs and two DIs participated in a scale comparison of the BRDF measurements of three achromatic samples at 550 nm in five measurement geometries. The realization of the scale of BRDF is a well-understood procedure, as explained in this paper, but the comparison of the measured values presents slight inconsistencies in some geometries, most likely due to the underestimation of measurement uncertainties. This underestimation was revealed and indirectly quantified using the Mandel-Paule method, which provides the interlaboratory uncertainty. The results from the presented comparison allow the present state of the BRDF scale realization to be evaluated, not only for classical in-plane geometries, but also for out-of-plane geometries.

Photometry is the metrology of light-optical radiation seen by the human eye due to its action on retinal photoreceptors. Its origins are closely tied to the International Commission on Illumination (CIE), which remains responsible for photometry standards and the language of light used in science and technology. When in 1931 it had become possible to model the response to light of the human eye based on reliable spectroradiometry data, the CIE published standard formulae for predicting the luminance of a stimulus. These and related colorimetry formulae are still in use, having been internationally agreed and adopted. Both fields continue to be the subject of active research and increasing accuracy. CIE S 026:2018 represents another milestone for the metrology of light (CIE, 2018a). It is the first standard where light is considered for its ability to evoke circadian and neurophysiological responses, and includes the spectral sensitivity of melanopsin-a retinal photopigment discovered, and shown to be contributing to and influencing responses from human intrinsically-photosensitive retinal ganglion cells (ipRGCs), only 20 years ago (Berson et al., 2002; Hattar et al., 2002; Provencio et al., 1998). These accessory visual functions also depend to some extent on inputs from the rods and three types of cones; until very recently, rods and cones (or "classical photoreceptors") were the only photoreceptors in visual models. If photometry standards are replaced with modern physiological data, consistent changes should be expected in the photometry of these accessory functions. This chapter outlines the current standards, their definitions and calculations, and how the main elements are related.

Main text The metrological equivalence of national measurement standards in the field of photometry and radiometry is determined by a set of key comparisons chosen and organised by the Consultative Committee of Photometry and Radiometry (CCPR) of the Comité international des poids et mesures (CIPM), working closely with the Regional Metrology Organisations (RMOs). In September 2009 the CCPR decided that a second round of the key comparison K3 Luminous Intensity be commenced. The National Research Council of Canada (NRC) was chosen to pilot this comparison. A total of 12 participants were selected from the three RMO group members: EURAMET&COOMET (6: IO-CSIC, LNE-CNAM, METAS, NPL, PTB, VNIIOFI), APMP&AFRIMETS (4: NMISA, NIM, NMIA, NMIJ), and SIM (2: NIST, NRC). The comparison was organised as a star comparison (NMI-Pilot-NMI) using incandescent standard lamps supplied by each NMI (National Metrology Institute) as the travelling comparison artifact. This report describes the comparison organisation (Section 2), the measurement methods and uncertainties achieved at all the participants and at the pilot (Sections 3 and 4), and the method for analysis and the results of the comparison according to this method (Section 4). It includes a comparison of the results of this comparison with the 1999 first round key comparison (Section 5). Section 6 presents a summary of the comparison. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/. The final report has been peer-reviewed and approved for publication by the CCPR, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Emerging applications require a calibration at 1 W with greater accuracy than is currently available. Conventional free beam absolute electrical substitution radiometers (ESRs) operate at cryogenic conditions have historically provided the highest accuracy but operate at optical power levels < 2 mW. To improve the accuracy of calibrations at 1 W, we compare possible approaches to realize a primary standard for 1 W optical power measurements. We describe and evaluate two diverse concepts based on bolometer detectors: The first design is an adapted cryogenic approach while the second system is operating at room temperature (RT). With the proposed uncertainty budgets, we estimate an expanded uncertainty for the RT layout to be < 0.06 % (k = 2) while the cryogenic design approaches 0.02 % (k = 2).

The digitalization of metrology poses a challenge to all members of the metrology community. We propose an approach for digital calibration certificates (DCCs) based on a PDF/A-3 solution that could be a stepping-stone towards the digitalization of metrological services. We present multiple applications of this approach by fulfilling discussed minimum requirements and satisfying needs from both customers and laboratories.

SID Symposium Digest of Technical PapersVolume 52, Issue S2 p. 354-354 Technical Sessions: Session 26: Display Measurement 2 (Display Measurement) 26.2: Invited Paper: Overview of Activities of the International Commission on Illumination (CIE) Dr. Peter Blattner, Corresponding Author Dr. Peter Blattner CIE President peter.blattner@metas.ch Federal Institute of Metrology, METAS, Bern-Wabern, SwitzerlandSearch for more papers by this author Dr. Peter Blattner, Corresponding Author Dr. Peter Blattner CIE President peter.blattner@metas.ch Federal Institute of Metrology, METAS, Bern-Wabern, SwitzerlandSearch for more papers by this author First published: 26 August 2021 https://doi.org/10.1002/sdtp.15120AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume52, IssueS2International Conference on Display Technology (ICDT 2021)August 2021Pages 354-354 RelatedInformation

Large effect pigments, widely used in various fields of industrial applications, produce characteristic visual textures known as sparkle and graininess, which need to be quantified by objective or subjective methods. The development of preliminary measurement scales for sparkle and graininess, whose recommendation is now under discussion in the International Commission on Illumination (CIE), is described in this article. These scales are absolute, linear and traceable to standards of optical radiation metrology. The main purpose of this article is to justify the convenience of adopting these preliminary measurements scales, showing clear evidence that they correlate well with subjective evaluations. Before standardization, these scales need to be validated with more experimental data, including different specimens and experimental systems from other research groups.

Specifications concerning road lighting and photometry of road surfaces were established more than 50 years ago. Road lighting design and road marking visibility were developed for vehicle driving. The observation distance defined by standards corresponds to interurban applications; however, within Europe these areas do not tend to be lit. The objective of the SURFACE project is to propose new geometries for the photometric characterisation of pavements, both adapted to different urban travel modes and new lighting technologies. This article reviews the available guidelines, standards, measuring devices and literature regarding geometries and road lighting applications, and presents the project SURFACE analysis and proposal. The SURFACE consortium recommends adding several new angles for different driving conditions and road users; 2.29° for urban environments and consistency with road marking standard, and 1° for extra-urban environment and consistency with previous geometries. A 5° angle, corresponding to 17-m viewing distance, could be an interesting compromise, suitable for urban driving at low speed, cycling and for scooters. The angles of 10° and 20° are under consideration for describing the boundary between diffuse and specular behaviour.

The International Commission on Illumination (CIE) is the umbrella organization of the various national lighting societies. On the one hand it is a standardization authority, on the other hand it is also a scientific organization. This article shows current fields of activity that are relevant for the display industry and provides some information about the concept of measurement uncertainty also applicable to the measurement of displays.

This document brings together the definitions and the tables of numerical values for photometry already adopted (or recommended) and published, by the Conférence Générale des Poids et Mesures (CGPM), by the Comité International des Poids et Mesures (CIPM), or by the Commission Internationale de l’Eclairage (CIE). This document provides the link between the definition of the candela in the International System of Units (SI) and the internationally agreed spectral luminous efficiency functions for human vision published by the CIE, including those for mesopic vision and for photopic vision for a 10° field of view, in addition to those for photopic vision for a 2° field of view and for scotopic vision. The definitions of photometric units and quantities have also been updated with the reformulated definition of the candela in the International System of Units (SI) 2019 and the latest definitions of the photometric quantities by the CIE.

This document brings together the definitions and the tables of numerical values for photometry already adopted (or recommended) and published, by the Conference Generale des Poids et Mesures (CGPM), by the Comite International des Poids et Mesures (CIPM), or by the Commission Internationale de l'Eclairage (CIE). This document provides the link between the definition of the candela in the International System of Units (SI) and the internationally agreed spectral luminous efficiency functions for human vision published by the CIE, including those for mesopic vision and for photopic vision for a 10 degrees field of view, in addition to those for photopic vision for a 2 degrees field of view and for scotopic vision. The definitions of photometric units and quantities have also been updated with the reformulated definition of the candela in the International System of Units (SI) 2019 and the latest definitions of the photometric quantities by the CIE.

The article describes the main activities of the International Commission on Illumination in recent years. The most important publications are reflecting recent developments in lighting science and industry, including LED sources and luminaires test methods, fundamental recommendations concerning colorimetry, discomfort caused by glare from luminaires with a non-uniform luminance, as well as intelligent control of lighting systems. Human centric lighting and the non-visual effects of light on humans was highlighted. To promote standardization in the field of horticultural lighting the CIE is in the process of establishing a new JTC. In view of COVID‑19 pandemic outspread the use of germicidal UV radiation is of relevance to reduce both contact spread and airborne transmission of infectious agents. The CIE is responsible for worldwide standardization of the fundamentals, including metrology and vocabulary, as well as lighting education. The CIE considers it important to make digital products including validated calculation tools, apps, databases and machine-readable documents more available for many experts and it takes a step in this direction by provide open access to the individual CIE publications.

To investigate, select and publish an LED reference spectrum to complement the CIE Standard Illuminant A in photometric calibrations, a new technical committee has been recently created by CIE.This technical committee requires defining a spectral mismatch index to quantify the match of spectral power distributions (SPDs) of real sources to the selected reference spectrum.A proposal for such an index is given here, assuming that the spectral mismatch index of the SPD of a real source is directly related to the spectral mismatch systematic error introduced when the photometric quantity is measured using a photometer which is calibrated to a light source with the reference SPD.Finally, the value of this index is discussed and interpreted in photometric terms.

CIE TC 2-90 is currently working to propose a reference spectrum for use in photometer calibrations as a complement to CIE illuminant A, based on the white LED illuminant LED-B3 recently published by CIE as part of CIE 015: Colorimetry, 4th edition (CIE 2018). Calibrating photometers with sources realizing LED-B3 is expected to reduce spectral mismatch errors in photometric measurements for a wide range of light sources and will alleviate the dependence on halogen lamps for photometric calibrations. In order to compare source spectra realizing LED-B3 to equivalents over the full wavelength range of radiation emission of the source, an extrapolation method for LED-B3 beyond the wavelength range of its current definition (380 nm to 780 nm) will have to be defined. We present models for the extrapolation of phosphor converted white LED spectra beyond the visible wavelength range and apply them to LED-B3 as well as measured spectra of white LED products.