Angular aperture
From Free net encyclopedia
Template:Unreferenced The angular aperture of a lens is the apparent angle of the lens aperture as seen from the focal point:
- <math>a = 2 \arctan \frac {A} {2 f}</math>
where
- <math>f</math> is the focal length
- <math>A</math> is the diameter of the aperture.
The angular aperture is approximately equal to twice the numerical aperture of the lens.
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