General Archives - All Things Lighting® Association https://www.allthingslighting.org/category/academic-articles-and-research/general/ Illuminating the Complicated! Wed, 05 Nov 2025 00:00:55 +0000 en-US hourly 1 https://www.allthingslighting.org/wp-content/uploads/2023/08/cropped-ATLA-favicon2-32x32.jpg General Archives - All Things Lighting® Association https://www.allthingslighting.org/category/academic-articles-and-research/general/ 32 32 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 Defining Far-Ultraviolet https://www.allthingslighting.org/defining-far-ultraviolet/ https://www.allthingslighting.org/defining-far-ultraviolet/#respond Fri, 12 Nov 2021 00:00:49 +0000 http://test.allthingslighting.org/?p=2302 In these uncertain times, there is increasingly persuasive evidence that “far-UV” radiation is effective in inactivating the SARS-CoV-2 virus and other pathogens, but without the health risks of germicidal ultraviolet radiation. Unfortunately, this technology has some of the hallmarks of a “miracle cure,” which has become an irresistible attractant for charlatans and hucksters of all […]

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]]> https://www.allthingslighting.org/defining-far-ultraviolet/feed/ 0 Spherical Irradiance and Aerosols https://www.allthingslighting.org/spherical-irradiance-and-aerosols/ https://www.allthingslighting.org/spherical-irradiance-and-aerosols/#respond Thu, 20 Aug 2020 05:12:29 +0000 https://www.allthingslighting.org/?p=1879 Lighting designers will be familiar with the illuminance of a planar surface, which is measured in lumens per square meter (or foot). The irradiance of a planar surface by a germicidal radiation source is conceptually the same, except that it is measured in watts per square meter (W/m2). Most designers, however, will not be familiar […]

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]]> https://www.allthingslighting.org/spherical-irradiance-and-aerosols/feed/ 0 Solid Angles https://www.allthingslighting.org/truly-understanding-luminous-intensity/ https://www.allthingslighting.org/truly-understanding-luminous-intensity/#respond Sat, 16 Feb 2019 00:32:04 +0000 https://www.allthingslighting.org/?p=294 Ian Ashdown, P. Eng., FIES, Senior Scientist, SunTracker Technologies Ltd.   Published: 2014/07/26 Do you suffer from math anxiety? A surprising number of us do (e.g., Wigfield 1988). I would tell you the exact numbers, but you would need to understand statistical analysis … Fortunately, we can mostly muddle through our lives without having to […]

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]]> https://www.allthingslighting.org/truly-understanding-luminous-intensity/feed/ 0 Understanding Mesopic Photometry https://www.allthingslighting.org/understanding-mesopic-photometry/ https://www.allthingslighting.org/understanding-mesopic-photometry/#respond Fri, 15 Feb 2019 22:56:14 +0000 https://www.allthingslighting.org/?p=288 Ian Ashdown, P. Eng., FIES, Senior Scientist, SunTracker Technologies Ltd. Published: 2013/10/08  If you are involved with outdoor area or roadway lighting design, you will undoubtedly encounter such terms as mesopic multipliers, scotopic lumens, and S/P ratios, and you will sooner or later need to consider mesopic photometry in your design efforts. For example, you […]

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]]> https://www.allthingslighting.org/understanding-mesopic-photometry/feed/ 0 Solar Illumination https://www.allthingslighting.org/solar-illumination/ https://www.allthingslighting.org/solar-illumination/#respond Fri, 15 Feb 2019 22:39:56 +0000 https://www.allthingslighting.org/?p=280 Ian Ashdown, P. Eng., FIES, Senior Scientist, SunTracker Technologies Ltd.    Published: 2015/01/21 Lighting design is based in part on the reasonable assumption that photometric units have precise definitions. The candela, for example, has a precise mathematical definition: “The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation […]

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]]> https://www.allthingslighting.org/solar-illumination/feed/ 0 Seeing Ultraviolet https://www.allthingslighting.org/seeing-ultraviolet/ https://www.allthingslighting.org/seeing-ultraviolet/#respond Fri, 15 Feb 2019 22:34:31 +0000 https://www.allthingslighting.org/?p=276 Ian Ashdown, P. Eng., FIES, Senior Scientist, SunTracker Technologies Ltd.   Published: 2015/10/26 UPDATE 15/11/08 – The following text briefly notes that some people can see near-ultraviolet radiation following cataract surgery due to the UV transmittance of their artificial intraocular lens. An example of this is reported in considerable detail here. What does it mean […]

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]]> https://www.allthingslighting.org/seeing-ultraviolet/feed/ 0 Rethinking the Photometric Data File Format https://www.allthingslighting.org/rethinking-the-photometric-data-file-format/ https://www.allthingslighting.org/rethinking-the-photometric-data-file-format/#respond Fri, 15 Feb 2019 22:32:40 +0000 https://www.allthingslighting.org/?p=274 Ian Ashdown, P. Eng., FIES, Senior Scientist, SunTracker Technologies Ltd. Published: 2017/03/01  If you perform lighting design calculations today, you can thank the efforts of the IES Computer Committee (IESCC) some thirty years ago. Its members recognized an industry need, and so developed and published IES LM-63-86, IES Recommended Standard File Format for Electronic Transfer […]

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]]> https://www.allthingslighting.org/rethinking-the-photometric-data-file-format/feed/ 0 Mesopic Photometry and Statistics https://www.allthingslighting.org/mesopic-photometry-and-statistics/ https://www.allthingslighting.org/mesopic-photometry-and-statistics/#respond Fri, 15 Feb 2019 22:14:18 +0000 https://www.allthingslighting.org/?p=266 Ian Ashdown, P. Eng., FIES, Senior Scientist, SunTracker Technologies Ltd.   Published: 2014/04/21 One of the joys of statistics is that you can never be proven wrong … In a previous All Things Lighting article titled “Understanding Mesopic Photometry” (October 8th, 2013), I wrote: Some publications on mesopic lighting have indicated that the S/P ratio […]

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]]> https://www.allthingslighting.org/mesopic-photometry-and-statistics/feed/ 0 In Search of Luminance https://www.allthingslighting.org/in-search-of-luminance/ https://www.allthingslighting.org/in-search-of-luminance/#respond Fri, 15 Feb 2019 21:33:21 +0000 https://www.allthingslighting.org/?p=254 Ian Ashdown, P. Eng., FIES, Senior Scientist, SunTracker Technologies Ltd. Published: 2014/11/18 The IES Lighting Handbook, Tenth Edition (IES 2010), describes luminance as “perhaps the most important quantity in lighting design and illuminating engineering.” This is an accurate but curious description, as the editors neglected to include an entry for Section 5.7.3, Luminance, in the […]

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