Results

Project results

Methods for traceable and validated measurement of temporal light modulation (Objectives 1 and 2)

Based on the models given in IEC TR 63158:2018 and IEC TR 61547-1:2020, uncertainty components, which affect TLM quantities for flicker and the stroboscopic effect, have been identified. To propagate these uncertainties, from the time domain to PstLM and SVM, models have been built. Using these models, sensitivity coefficients for uncertainty propagation have been determined for various waveforms. This uncertainty analyses will be an input to calibration of TLM measurement devices. Typical performance of measurement devices can be expressed in quality indices, which characterise how a physical effect influences the instrument’s reading. For TLM measurement devices quality indices have been defined for frequency response and dynamic range of signal. The next step is to characterise measurement devices according to the new quality indices using LED- and laser-based facilities, which will be adapted for this purpose. Quality indices can be used for instrument classification, helping prospective instrument buyers selecting suitable TLM measurement equipment.

Novel methods for TLM measurement (Objective 3)

In an experimental study, conducted in an environment illuminated with multiple light sources, image sequences at frame rates of 8 kHz and 4 kHz have been taken with RGB cameras. For each colour channel of the cameras, (namely, red, green, and blue,) the TLM waveforms have been extracted, for a region of interest marked in the image sequences. The results reveal the operation principle of tuneable white LED-based lamps, which consist of coloured LEDs, and underlined the need to evaluate spectrally and spatially resolved TLM measurements.

Measurements taken with an imaging luminance measurement device (ILMD), on different lamps and luminaires, demonstrated the feasibility of TLM measurements with such devices. The measurement modes used will be improved and further developed.

Model for the visibility of the phantom array effect

The work related to this objective has not started yet.

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Publications

• P.R. Dekker and A. L. van Bloois, ‘Facility for calibration of photometers for temporal light modulation’, in Proceedings of the Conference CIE 2021, Online (hosted by NC Malaysia), Dec. 2021, pp. 240–244. doi: 10.25039/x48.2021.OP27 – Available online
• Thorseth, J. Lindén, and C.A. Bouroussis, ‘Sensitivity analysis on the effect of measurement noise and sampling frequency on the calculation of the temporal light artefacts’, in Proceedings of the Conference CIE 2021, Online (hosted by NC Malaysia), Dec. 2021, pp. 245–254. doi: 10.25039/x48.2021.OP28 – Available online
• R. Koch and R. Zuber, ‘Anti-aliasing filter effects on sampling frequency and effects of mathematical implementation’, in Proceedings of the ‘CIE Expert Tutorial and Symposium on the Measurement of Temporal Light Modulation, October 2022, National Technical University of Athens, Greece’, p.46-53, DOI 10.25039/x49.2022.P10 – Available online

 Other project results

• P.R. Dekker and C.A. Bouroussis, ‘Measurement of temporal light modulation (TLM)’, presentation at the ‘CIE Expert Tutorial and Symposium on the Measurement of Temporal Light Modulation, October 2022, National Technical University of Athens, Greece’ (tutorial presentation) 
• A. Thorseth, ‘Estimation of measurement and calculation uncertainties’, presentation at the ‘CIE Expert Tutorial and Symposium on the Measurement of Temporal Light Modulation, October 2022, National Technical University of Athens, Greece’ (tutorial presentation)
• X. Kong, M. Perz, C. Martinsons, M.N. Tengelin, I. Heynderickx, ‘Towards modelling the visibility of the phantom array effect’, presentation and abstract for the ‘CIE Expert Tutorial and Symposium on the Measurement of Temporal Light Modulation, October 2022, National Technical University of Athens, Greece’ – Abstract available online
• E. Ikonen, R. Nordlund, V. Mantela, J. Askola and P. Kärhä, ‘Improvement in the temporal light artefact metrics of commercial LED lamps’, presentation and abstract for the ‘CIE Expert Tutorial and Symposium on the Measurement of Temporal Light Modulation, October 2022, National Technical University of Athens, Greece’ – Abstract available online
• V. Mantela, R. Nordlund, J. Askola, P. Kärhä and E. Ikonen, ‘Novel implementations of digital meters for flicker and stroboscopic effect’, presentation and abstract for the ‘CIE Expert Tutorial and Symposium on the Measurement of Temporal Light Modulation, October 2022, National Technical University of Athens, Greece’ – Abstract available online
• Roope Nordlund, ‘Validation for measurement of Temporal Light Artefacts on LED light sources’, Thesis submitted for examination for the degree of Master of Science in Technology, Aalto University - School of Electrical Engineering, Espoo 28.2.2022 – Available online