This page is optimized for large screens. Zooming may cause some display problems.

glossary

Aperture : diaphragm limiting the number of light rays that are able to propagate
Clear aperture: aperture diameter of an optical system
Object: element (point, line, plane, or whatever,…) of the space linked to another element called image in a way that rays coming from the object and transmitted by an optical system focus on the image ; object and image are said to be conjugate by the optical system
Image: conjugate of an object by an optical system (see object)
Refraction index: for a transparent medium, ratio between the light speed in the air and the light speed in the medium ; for a reflective surface in the air or vacuum, the refraction index is « - 1 »
Numerical aperture ( optical system ): dimensionless number characterizing the aperture in the object space or in the image space and defined as the product of the refraction index by the sine of half the aperture angle