Vékonylencsés

Vékonylencsés is a term used in optics, derived from the Hungarian words for “thin” (vékony) and “lens” (lencse). It describes a lens or optical system that can be modeled using the thin-lens approximation, in which the lens thickness is considered negligible compared with its focal length and the dimensions of the system.

In the vékonylencsés model, light rays are assumed to refract at a single, infinitesimally thin plane. The key relation is the thin-lens formula, 1/f = 1/v + 1/u, where f is the effective focal length, u is the object distance, and v is the image distance. The magnification is m = -v/u. Because the model uses a single refracting plane, principal planes are effectively collapsed into that plane, simplifying ray tracing to paraxial rays near the optical axis.

The vékonylencsés approximation is widely used for educational purposes, initial lens design, and quick imaging calculations where rays remain close to the axis and angles are small. It is most accurate when the lens has a small thickness relative to its focal length and the aperture is not too large, such that aberrations remain minor.

Limitations include its inaccuracy for thick lenses, high numerical apertures, or wide-field imaging, where thickness effects and principal-plane separations become important. In such cases, thick-lens theory or full ray-tracing models are required, which account for the actual geometry of the lens surfaces and their refractive interfaces.

See also: thin lens, thick lens, paraxial approximation, geometric optics.