Allard's law: Difference between revisions

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|Meaning=An equation used in predicting the [[night visual range]] of self-luminous targets.
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|Explanation=Assume a [[light]] source at distance ''x'' from an observer and having ([[monochromatic]]) [[luminous]]  power ''P''<sub>''v''</sub> in that person's direction. Then for uniform [[extinction coefficient]] &#x003c3;, the [[illuminance]]  ''E''<sub>''v''</sub> reaching the observer is  <blockquote>[[File:ams2001glos-Ae15.gif|link=|center|ams2001glos-Ae15]]</blockquote> When ''E''<sub>''v''</sub> equals the [[threshold illuminance]] for a given background [[luminance]] and [[detection]]  probability, ''x'' is the [[night visual range]], or maximum distance for detecting the light source.
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== Allard's law ==
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<div class="definition"><div class="short_definition">An equation used in predicting the [[night visual range]] of self-luminous targets.</div><br/> <div class="paragraph">Assume a [[light]] source at distance ''x'' from an observer and having ([[monochromatic]]) [[luminous]]  power ''P''<sub>''v''</sub> in that person's direction. Then for uniform [[extinction coefficient]] &#x003c3;, the [[illuminance]]  ''E''<sub>''v''</sub> reaching the observer is  <div class="display-formula"><blockquote>[[File:ams2001glos-Ae15.gif|link=|center|ams2001glos-Ae15]]</blockquote></div> When ''E''<sub>''v''</sub> equals the [[threshold illuminance]] for a given background [[luminance]] and [[detection]]  probability, ''x'' is the [[night visual range]], or maximum distance for detecting the light source.</div><br/> </div>
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Latest revision as of 22:16, 13 January 2024

An equation used in predicting the night visual range of self-luminous targets.
Assume a light source at distance x from an observer and having (monochromatic) luminous power Pv in that person's direction. Then for uniform extinction coefficient σ, the illuminance Ev reaching the observer is
ams2001glos-Ae15
When Ev equals the threshold illuminance for a given background luminance and detection probability, x is the night visual range, or maximum distance for detecting the light source.


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