Development of measurement methods and methodology for flicker and stroboscopic visibility

Important results from the project

The overall goal of the project has been to develop the National Metrology Insitute´s methods for determining quantifiable visual parameters and to be able to provide quality-assured measurements for modulated light. This has been carried out by: 1) Design and construction of a reference source with precisely adjustable parameters. 2) Validation of the sensitivity curve for SVM where 28 test subjects were included, which provided information on mean level and spread. 3) Development and validation of measurement methods and methodology for SVM and PstLM.

Expected long term effects

AP1: The source can be used to verify the National Metrology Institute´s measurement setups and to evaluate and demonstrate visual and non-visual effects that modulated light gives rise to. AP2: We have developed a sensitivity curve for SVM and will combine our data with previous studies for an improved stroboscopic visibility model based on a larger sample. AP3: The measurement method developed is used in the laboratory and we will participate in two international comparisons in the next year. The evaluations have also contributed to an ongoing EU project.

Approach and implementation

AP 1: The source is built with an LED driver controlled by a minicomputer. It was evaluated with a large number of different waveforms. AP 2: An optimized adaptive staircase method in psychometric experiments was used to test stroboscopic visibility in 28 subjects. The sensitivity curve is based on threshold values at frequencies below 900 Hz. AP3: The system has a maximum sampling rate of 50 kHz and meets requirements in current standards. The calculation algorithms are done in MATLAB. The system is validated with reference waveforms and international comparisons.