Definition of the optical axis within the scenery

For a sequential analysis of ray-tracing it is useful to define an optical axis on which the optical components are positioned.

This axis may be

• defined and manipulated by the positioning of the optics.
• initially defined and the optics are placed on this axis.

The direction change of the optical axis should be discussed. It can, for example, be useful to rotate the coordiante system according to the optical axis or use a global system in which the direction of the optical axes changes. The direction may change by the use of a mirror with a defined angle or by a misaligned lens.