Glossary
- Refracting surface: surface interfacing two transparent media with different refraction indexes
- 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 »
- Effective focal length: algebraic distance from the primary/secondary principal plane of an optical system to its front/back focal plane
- Front focal length: for an optical system, algebraic distance from the vertex of the first surface to the front focal point
- Back focal length: for an optical system, algebraic distance from the vertex of the last surface to the back focal point