Continuous-Spectrum Infrared Illuminator for Camera-PPG in Darkness
Wenjin Wang;Luc Vosters;Albertus C. den Brinker;Wang, Wenjin;Vosters, Luc;den Brinker, Albertus C.;
sensors2020Vol. 20pp. 3044-
209
wang2020sensorscontinuous-spectrum
Abstract
Many camera-based remote photoplethysmography (PPG) applications require sensing in near infrared (NIR). The performance of PPG systems benefits from multi-wavelength processing. The illumination source in such system is explored in this paper. We demonstrate that multiple narrow-band LEDs have inferior color homogeneity compared to broadband light sources. Therefore, we consider the broadband option based on phosphor material excited by LEDs. A first prototype was realized and its details are discussed. It was tested within a remote-PPG monitoring scenario in darkness and the full system demonstrates robust pulse-rate measurement. Given its accuracy in pulse rate extraction, the proposed illumination principle is considered a valuable asset for large-scale NIR-PPG applications as it enables multi-wavelength processing, lightweight set-ups with relatively low-power infrared light sources.