Spherical lens

This element represents a “real” lens with spherical front and back surfaces. Furthermore, the lens consists of an optical material, which carries the refractive index model among other data. The center thickness denotes the distance of the front and back surfaces at symmetry axis of the lens.

The optic shape decides which rays hit the lens (see Optic shape). Choose it so that the lens keeps a positive edge thickness: where the front and back surfaces would cross, e.g. beyond the rim of a thin biconvex lens, rays miss the rear surface.

Since this element encloses a volume of material, it can be operated as an amplifier: a pump scenario assigns it a gain model, and light travelling through the medium is amplified accordingly. Without such an assignment the lens is the passive component described here.

Analysis

• Energy Analysis

  During energy analysis, besides the common behaviour, this element does not alter the incoming the incoming light. The output is a copy of the input light. Above mentioned apertures are ignored.

• Ray tracing Analysis

  During ray tracing analysis, incoming rays are refracted on the frontsurface according to Snellius’ law of refraction. Inside the lens the ray propagate within the given medium. On the rearsurface, the rays are again refracted. A ray reaching a surface outside the optic shape misses the lens and follows the analyzer’s missed surface strategy.

• Ghost focus Analysis

  During this analysis, the lens behaves similar to the ray tracing analysis. A ray outside the optic shape passes the lens unchanged.

Ports

• input_1

  Input port. Corresponds to the frontsurface of the lens.

• output_1

  Light ouput. This port represents the light having passed the rear surface of the lens.

Properties

• front curvature

  Radius of curvature of the front surface. This value must not be zero. A positive value denotes a convex surface. The value infinity or -infinity denotes a flat surface.

• rear curvature

  Radius of curvature of the rear surface. This value must not be zero. A positive value denotes a concave surface. The value infinity or -infinity denotes a flat surface.

• center thickness

  Thickness of the lens center at its symmetry axis. This value must be positive and finite.

• material

  The (glass-) material the lens is made of. It carries the refractive index model — a constant value or a dispersion formula such as Sellmeier or Schott — which is what the refraction at both surfaces is calculated from.

• optic shape

  Transversal extent of the lens: the size the material is actually available in, the figure a supplier quotes next to the curvatures and the thickness. It decides which rays hit the lens. Defaults to a circle of 12.5 mm radius, i.e. the usual 1 inch mount. Both curvatures must reach its edge; Open is refused.