Home > Overview of animations > Teaching animation: Concept of numerical aperture
In this interactive animation the concept of the numerical aperture is illustrated.
Shown here is a converging lens focusing a light beam. Depending on the numerical aperture, the light is focused on different positions.
The animation was originally developed as a offline application for Windows and Macintosh systems and for integration into Microsoft PowerPoint slides. The online version presented here serve as a preview. The exe or app file can be downloaded free of charge from members area.
Here you see a lens focusing several parallel beams. Using the computergenerated controller, the shape of the lens and thus the numerical aperture can be changed. The appearance of the light beams is automatically updated.
The numerical aperture is an important measure in judging the resolution of an objective or a lens. In the case of a smaller numerical aperture, the angle at which the light beams are focused is sharp. In principle, lenses with small aperture angles have a lower resolution than lenses with large aperture angles.
The numerical aperture is calculated according to the following formula:
$$NA = n \cdot \sin{\sigma}$$
$NA$: Numerical Aperture
$n$: Refractive index of the medium
$\sigma$: Halfopening angle (divergence angle)
Title:  Teaching animation: Concept of numerical aperture 

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Authoring tool: Adobe Animate
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