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glossary
- Lens: optical component with two refractive surfaces axially symmetrical for redirecting the light in a controlled manner
- 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)
- Effective focal length: algebraic distance from the primary/secondary principal plane of an optical system to its front/back focal plane
- Aperture : diaphragm limiting the number of light rays that are able to propagate
- Transverse magnification: size ratio of an image and an object, the image being conjugated to the object by an optical system; for centered optical systems, the transverse magnification is defined with objects in a plane perpendicular to the optical axis - transverse magnification is then positive if object and image have the same orientation and negative otherwise
- Front focal plane: plane perpendicular to the optical axis whose image plane by the optical system is located at infinity
- Back focal plane: plane conjugate by an optical system of an object plane perpendicular to the optical axis and located at infinity
- Aperture : diaphragm limiting the number of light rays that are able to propagate
- 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