Cardinal point

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Notion

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Science and technology

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What Wikipedia says

In Gaussian optics, the cardinal points consist of three pairs of points located on the optical axis of a rotationally symmetric, focal, optical system. These are the focal points, the principal points, and the nodal points; there are two of each.

Excerpt from the Wikipedia article “Cardinal point (optics)”, under the CC BY-SA 4.0 license. Read the article on Wikipedia

Image: en:User:DrBob, CC BY-SA 3.0, via Wikimedia Commons.