Lighting Archives - All Things Lighting® Association https://www.allthingslighting.org/category/academic-articles-and-research/lighting/ Illuminating the Complicated! Fri, 01 May 2026 20:12:53 +0000 en-US hourly 1 https://www.allthingslighting.org/wp-content/uploads/2023/08/cropped-ATLA-favicon2-32x32.jpg Lighting Archives - All Things Lighting® Association https://www.allthingslighting.org/category/academic-articles-and-research/lighting/ 32 32 Technical Report: Photobiological Hazard Assessment of Orbital Solar Reflectors https://www.allthingslighting.org/technical-report-photobiological-hazard-assessment-of-orbital-solar-reflectors/ https://www.allthingslighting.org/technical-report-photobiological-hazard-assessment-of-orbital-solar-reflectors/#respond Fri, 01 May 2026 20:08:58 +0000 https://www.allthingslighting.org/?p=5330 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 62471:2006 Photobiological Safety of Lamps and Lamp Systems. OSRs are intended to provide primary or supplemental lighting and […]

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]]> https://www.allthingslighting.org/technical-report-photobiological-hazard-assessment-of-orbital-solar-reflectors/feed/ 0 Intro to Horticultural Lighting https://www.allthingslighting.org/intro-to-horticultural-lighting/ https://www.allthingslighting.org/intro-to-horticultural-lighting/#respond Wed, 04 Feb 2026 17:40:12 +0000 https://www.allthingslighting.org/?p=5282 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 differs from architectural lighting. I was surprised by the […]

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]]> https://www.allthingslighting.org/intro-to-horticultural-lighting/feed/ 0 Refinements to the Worthing Relationship – A Quantum Version of Wien’s Displacement Law https://www.allthingslighting.org/refinements-to-the-worthing-relationship-a-quantum-version-of-wiens-displacement-law/ https://www.allthingslighting.org/refinements-to-the-worthing-relationship-a-quantum-version-of-wiens-displacement-law/#respond Wed, 05 Nov 2025 00:00:55 +0000 https://www.allthingslighting.org/?p=5227 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 temperature. However, not all uses of light are based on radiant flux. In particular, […]

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]]> https://www.allthingslighting.org/refinements-to-the-worthing-relationship-a-quantum-version-of-wiens-displacement-law/feed/ 0 Finding the Danger Zone of the Circadian Stimulus Model: A Summary https://www.allthingslighting.org/finding-the-danger-zone-of-the-circadian-stimulus-model-a-summary/ https://www.allthingslighting.org/finding-the-danger-zone-of-the-circadian-stimulus-model-a-summary/#respond Tue, 04 Nov 2025 23:55:01 +0000 https://www.allthingslighting.org/?p=5248 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 that separates the model from other contemporary circadian lighting models is its discontinuous action […]

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]]> https://www.allthingslighting.org/finding-the-danger-zone-of-the-circadian-stimulus-model-a-summary/feed/ 0 Can Designs and Measurements Based on the Circadian Stimulus Model Stand the Test of Time? https://www.allthingslighting.org/can-designs-and-measurements-based-on-the-circadian-stimulus-model-stand-the-test-of-time/ https://www.allthingslighting.org/can-designs-and-measurements-based-on-the-circadian-stimulus-model-stand-the-test-of-time/#respond Tue, 13 Aug 2024 06:01:18 +0000 https://www.allthingslighting.org/?p=4817 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 [WELL v2]; and circadian light, or CLA [UL 2019]. Both m-EDI and EML have a continuous action spectrum, which means […]

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]]> https://www.allthingslighting.org/can-designs-and-measurements-based-on-the-circadian-stimulus-model-stand-the-test-of-time/feed/ 0 Horticultural Lighting Design and Déjà Vu https://www.allthingslighting.org/horticultural-lighting-design-and-deja-vu/ https://www.allthingslighting.org/horticultural-lighting-design-and-deja-vu/#respond Mon, 13 Sep 2021 00:25:34 +0000 http://test.allthingslighting.org/?p=2316 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 an important lesson from four decades of architectural lighting. The Importance of Design Data Prior to the […]

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]]> https://www.allthingslighting.org/horticultural-lighting-design-and-deja-vu/feed/ 0 Defining Photosynthetic Photon Efficacy https://www.allthingslighting.org/defining-photosynthetic-photon-efficacy/ https://www.allthingslighting.org/defining-photosynthetic-photon-efficacy/#respond Fri, 26 Jun 2020 19:39:58 +0000 https://www.allthingslighting.org/?p=1859 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 400 nm to 700 nm. Exposing plants to far-red radiation (defined as 700 nm to 800 nm) […]

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]]> https://www.allthingslighting.org/defining-photosynthetic-photon-efficacy/feed/ 0 Thoughts on Color Rendering https://www.allthingslighting.org/thoughts-on-color-rendering/ https://www.allthingslighting.org/thoughts-on-color-rendering/#respond Fri, 15 Feb 2019 22:52:55 +0000 https://www.allthingslighting.org/?p=286 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: LightingEurope supports to continue the use of the existing Color Fidelity metric CRI including eight reference colors. LightingEurope supports to […]

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]]> https://www.allthingslighting.org/thoughts-on-color-rendering/feed/ 0 The Kruithof Curve https://www.allthingslighting.org/the-kruithof-curve/ https://www.allthingslighting.org/the-kruithof-curve/#respond Fri, 15 Feb 2019 22:50:02 +0000 https://www.allthingslighting.org/?p=284 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 10.1080/15502724.2016.1159137.) critically examined 29 studies in which the Kruithof curve was investigated. The author concluded that “… these [studies] do […]

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]]> https://www.allthingslighting.org/the-kruithof-curve/feed/ 0 Sports Lighting Regulations https://www.allthingslighting.org/sports-lighting-regulations/ https://www.allthingslighting.org/sports-lighting-regulations/#respond Fri, 15 Feb 2019 22:43:52 +0000 https://www.allthingslighting.org/?p=282 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 relates to sports lighting regulations. I was told the name of the organization I […]

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]]> https://www.allthingslighting.org/sports-lighting-regulations/feed/ 0 Horticultural Lighting Metrics https://www.allthingslighting.org/horticultural-lighting-metrics/ https://www.allthingslighting.org/horticultural-lighting-metrics/#respond Fri, 15 Feb 2019 21:28:17 +0000 https://www.allthingslighting.org/?p=249 Ian Ashdown, P. Eng., FIES, Senior Scientist, SunTracker Technologies Ltd.   Published: 08/04/2017  UPDATE 17/08/26 – This article was first published on August 25th, 2017 in Urban Ag News. It was all so easy until recently. Plants require light in order to grow, and so we provided them with daylight and/or electric lighting. Given the […]

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]]> https://www.allthingslighting.org/horticultural-lighting-metrics/feed/ 0 Giving Light https://www.allthingslighting.org/giving-light/ https://www.allthingslighting.org/giving-light/#respond Fri, 15 Feb 2019 21:23:17 +0000 https://www.allthingslighting.org/?p=244 Ian Ashdown, P. Eng., FIES, Senior Scientist, SunTracker Technologies Ltd. Published: 2014/05/12 Giving light … this phrase symbolizes a new philosophy of lighting design, a philosophy in the sense of how we think about the lighting design process. Much like the modernist movement in architectural design a century ago, it offers a reconciliation of lighting […]

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]]> https://www.allthingslighting.org/giving-light/feed/ 0 Blue Light Hazard… Or Not? https://www.allthingslighting.org/blue-light-hazard-or-not/ https://www.allthingslighting.org/blue-light-hazard-or-not/#respond Tue, 12 Feb 2019 03:03:21 +0000 https://www.allthingslighting.org/?p=51 Ian Ashdown, P. Eng., FIES, Senior Scientist, SunTracker Technologies Ltd.   Published: 2014/11/05 As a professional lighting designer, you will likely have read about the “blue light hazard” associated with white light-emitting diodes. You will have seen warnings like this (Willmorth 2014a): “… long term exposure to blue light at 441nm caused lesions on the […]

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