Measurement of temporal light modulation using a hyperspectral camera

In the European Union, temporal light artifacts (TLAs) have recently been regulated for mains-connected LED lamps and luminaires available on the market. However, the limitations are only on white LED sources. Colored LED sources are not under current regulation, although they are often used as components to create a source that looks like a white source to an observer. We present a measurement setup based on a hyperspectral camera to measure different types of luminaires simultaneously to quantify the spectral components of the TLA metrics. The camera has one-megapixel spatial resolution and can measure at 1000 different wavelengths with a bandwidth of 10 nm. The sampling frequency of the camera was extended from 100 frames per second (fps) to 1000 fps using triggering with a varied delay, and waveforms within an integration time of 1 s were captured. We demonstrate measurements of white LED lamps at wavelengths of 450 nm, 550 nm and 650 nm, and compare the results of the TLA metrics with other measurement setups. We observed that for one of the lamps, the hyperspectral measurements deviated only 3% from the reference values, while for the other lamp, the demonstrative measurement system did not have sufficient performance, which increased the deviations significantly.