The recording of the CIE US National Committee webinar "Measuring Light for Vision, Health, and Everything Else" is now available for viewing on CIE Vimeo channel. This webinar was held in collaboration with the Illuminating Engineering Society (IES) on 25 October 2024.
The webinar was opened by Prof. Craig Bernecker, President of the US National Committee of the CIE, who provided an introduction to the CIE and the US National Committee.
The session featured two distinguished speakers:
- Dr. Alan L. Lewis (CIE USNC Past President and IES Past President)
- Dr. Jennifer A. Veitch (CIE President)
The webinar focused on the history and evolution of the spectral luminous efficiency function V(λ), a fundamental concept in photometry. It explored its origins in research conducted by the US National Committee of the CIE and its adoption internationally by the CIE in 1924. 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 (2o) 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? Dr. Lewis and Dr. Veitch discussed the current state of photometry, the pros and cons of updating the V(λ) function.
This presentation celebrated the history of V(λ) and showed 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.
To view the full recording of this insightful session, please visit here.