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Executive Summary This report details a photobiological hazard assessment of the general concept of Orbital Solar Reflectors (OSRs). A recent proposal, Reflect Orbital’s proposed Earendil-1 satellite is used as an exemplar. The analysis was conducted following IEC...
Introduction This article is based on a presentation I had the pleasure of delivering at the recent Canada Light Expo 2025 in Toronto. My aim with the presentation was to offer a brief overview of some key aspects of horticultural lighting and to highlight how it...
Refinements to the Worthing Relationship – A Quantum Version of Wien’s Displacement Law Eric Bretschneider, Ph.D. Abstract Wien’s Displacement Law is a simple equation that allows calculation of the peak wavelength for a black body light source as a function of...
Author: Alexander Willemsen, Degree of Master of Science of Engineering Based on a paper authored by Eric Bretschneider, Ph.D. The Circadian Stimulus (CS) model is one of the most well-known models for quantifying the circadian impact of lighting. One striking feature...
Author: Eric Bretschneider, Ph.D INTRODUCTION When considering the potential circadian impact of lighting, lighting designers have a choice between three different models: melanopic equivalent daylight illuminance, or m-EDI [CIE 2018]; equivalent melanopic lux, or EML...
The phrase déjà vu translates from French as “already seen,” which nicely describes a current issue with horticultural lighting design. The introduction of LED technology may have kick-started horticultural lighting as an innovative industry, but we have yet to learn...
There has been some discussion online and in presentations recently about the issue of photosynthetic photon flux. The argument goes as follows: Photosynthetically Active Radiation (PAR) is somewhat arbitrarily defined as optical radiation within the spectral range of...
Ian Ashdown, P. Eng., FIES, Senior Scientist, SunTracker Technologies Ltd. Published: 2014/01/05 UPDATE 14/10/06 - LightingEurope, the "Voice of the Lighting Industry," has just published their LightingEurope Position Paper on Color Quality. To summarize:...
Ian Ashdown, P. Eng., FIES, Senior Scientist, SunTracker Technologies Ltd. Published: 2015/01/12 UPDATE 16/04/09 - This metastudy: Fotois, S. 2106. "A Revised Kruithof Graph Based on Empirical Data," Leukos. (Published online 08 April 2016, DOI...
Ian Ashdown, P. Eng., FIES, Senior Scientist, SunTracker Technologies Ltd. Published: 2016/04/30 This blog article has a somewhat frustrating history. About a year ago, I was asked to volunteer my time to write a primer of light and color as it...