Angular aperture: Difference between revisions
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The '''angular aperture''' of a [[lens (optics)|lens]] is the apparent [[angle]] of the lens [[aperture]] as seen from the [[focal point]]: |
The '''angular aperture''' of a [[lens (optics)|lens]] is the apparent [[angle]] of the lens [[aperture]] as seen from the [[Focus (optics)|focal point]]: |
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:<math>a = 2 \arctan \frac {A} {2 f}</math> |
:<math>a = 2 \arctan \frac {A} {2 f}</math> |
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where |
where |
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:<math>f</math> is the [[focal length]] |
:<math>f</math> is the [[focal length]] |
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:<math>A</math> is the diameter of the aperture |
:<math>A</math> is the diameter of the aperture. |
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The angular aperture is approximately equal to twice the [[numerical aperture]] of the lens. |
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==See also== |
==See also== |
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*[[f-number]] |
*[[f-number]] |
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*[[ |
*[[Numerical aperture]] |
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[[Category:Optics]] |
[[Category:Optics]] |
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[[Category:Angle]] |
[[Category:Angle]] |
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Revision as of 14:51, 15 February 2006
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The angular aperture of a lens is the apparent angle of the lens aperture as seen from the focal point:
where
- is the focal length
- is the diameter of the aperture.
The angular aperture is approximately equal to twice the numerical aperture of the lens.