Sole Morillo, A, Lambert Cause, J, da Silva, B & Stiens, J 2024, Evaluation of the impact of LED viewing angle and optical window choice on photoplethysmography signal quality. in I Gannot, I Gannot & K Roodenko (eds), Photoplethysmography (PPG) is a non-invasive optical technique used to extract physiological information by means of light interaction with the skin. PPG is widely used in pulse oximeters, and the evolution of wearable technologies is further enlarging its applications. A great variety of influencing factors impact the PPG waveform, making the correct feature extraction difficult and, therefore, limiting the accuracy of many PPG applications. The device hardware and software are among these influencing factors. This study evaluates the impact on the PPG signal quality of the LED viewing angle (luminous aperture) and the protective glass material, thickness, and anti-reflective coating, both important building blocks of a PPG sensor. Results suggest that the larger the viewing angle, the smaller the detected signal amplitude. The protective glass properties on the contrary does not seem to impact the detected signal amplitudes.. 2024 edn, vol. 12835, 128350Q, Progress in Biomedical Optics and Imaging - Proceedings of SPIE, vol. 12835, SPIE, Optical Fibers and Sensors for Medical Diagnostics, Treatment, and Environmental Applications XXIV, pp. 157-169, SPIE Photonics West 2024, San Fransisco, California, United States, 27/01/24. https://doi.org/10.1117/12.3001707