Measuring Light for Vision, Health, and Everything Else
Recorded On: 10/25/2024
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About this Course
The IES offers Educational Webinars throughout the year, purposefully spanning a broad range of topics and speaker expertise.
Description: Everybody in the lighting world knows (or should know) that the basis of photometry is the spectral luminous efficiency function V(λ), but did you know that its basis is research conducted in the USA under the auspices of the US National Committee of the CIE? 2024 marks the centenary of V(λ) being adopted internationally by the CIE and the beginnings of physical measurement of optical radiation.
The 1924 definition of V(ʎ) is based on psychophysical experiments measuring brightness perception. It has long been recognized that it underestimates visual sensitivity at short wavelengths and is appropriate only for small (2°) visual fields. Recent research has made it possible to propose a new standard based on the physiological properties of the visual system – but is it the right decision, to change the foundation of photometry? The presentation will describe the pros and cons.
V(λ) best describes light for vision but in recent years we have learned about new photoreceptors, the intrinsically photoreceptive retinal ganglion cells (ipRGCs), and have learned to measure light for its effects on these and the classically known rods and cones. This presentation will celebrate the history of V(λ) and show how we use it together with the CIE system of metrology for ipRGC-influenced effects of light to characterize light exposures, with pointers to how these measurements are coming to be reflected in lighting recommendations including ANSI/IES RP-46-23 Recommended Practice: Supporting the Physiological and Behavioral Effects of Lighting in Interior Daytime Environments.
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Jennifer A. Veitch
Dr. Jennifer A. Veitch serves as the President of the CIE for the 2023-2027 term. She is a psychological scientist with expertise in environmental psychology, and has been a Research Officer at the National Research Council of Canada since 1992. Dr. Veitch investigates interactions of people and their physical environments, including lighting quality and light source effects on performance, mood, and health. Her research is published in scientific journals and also influences recommendations and standards through the CIE, ISO, and the IES. Dr. Veitch is a Fellow of national and international associations in lighting and psychology. She received the Waldram Gold Pin for Applied Illuminating Engineering from the CIE in 2011 and the IES Medal Award in 2018. In November 2024 she will be inducted as a Fellow of the Royal Society of Canada.
Alan L. Lewis
Dr. Lewis retired as President of the New England College of Optometry in 2016 and continues working as a physiological optics consultant. He taught at the SUNY College of Optometry for 20 years where he was Director of Graduate Studies and then served for 8 years as Dean of the Michigan College of Optometry. He served two terms as president of the United States National Committee of CIE and served as president of the Illuminating Engineering Society of North America, and the Association of Schools and Colleges of Optometry. He is a Fellow of both the American Academy of Optometry and the IES and is a recipient of the IES Medal and the Marks Award. His research has primarily focused on environmental factors' role on visual performance with an emphasis on glare; he has also studied the physiological basis of color vision and receptor interactions. His most recent work has been on the role of spectral effects of roadway lighting and stereoscopic issues in robotic surgery.