Lighting Fundamentals Archives - All Things Lighting® Association

Refinements to the Worthing Relationship – A Quantum Version of Wien’s Displacement Law

Eric Bretschneider, Ph.D — Wed, 05 Nov 2025 00:00:55 +0000

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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Defining Far-Ultraviolet

Shirley Lang — Fri, 12 Nov 2021 00:00:49 +0000

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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Ultraviolet Radiation Terminology

Shirley Lang — Mon, 14 Sep 2020 05:03:03 +0000

A word of caution: I am going to be annoyingly pedantic here, but with good reason. The lighting industry has a century-long history of introducing unfamiliar technologies using familiar terminology. We later come to regret our choice of words when it becomes necessary to express precisely what we mean. Consider, for example, the term luminance. […]

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Spherical Irradiance and Aerosols

Shirley Lang — Thu, 20 Aug 2020 05:12:29 +0000

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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Photometry and Photosynthesis

Shirley Lang — Fri, 15 Feb 2019 22:22:39 +0000

Ian Ashdown, P. Eng., FIES, Senior Scientist, SunTracker Technologies Ltd. Published: 2014/12/10 UPDATE 15/04/13 — This article was first published on December 10, 2014. A revised version was published as “LED Lighting for Horticulture” in the Mar/Apr 2015 issue of LED Professional Review (www.led-professional.com). This update includes information from the published article. UPDATE 15/11/05 — […]

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