All rays emanate from the first surface in the system (the Object surface) and travel until they reach the last surface (the Image surface). The radius of the Object surface determines how far apart the source point of the rays are.
You can specify:
- the number of wavelengths (Nwavelength)
- the number of source points (NsrcPt)
- and the number of fan rays (Nangle)
Total number of rays are the product of these 3 values (Nwavelength * NsrcPt * Nangle). One would typically make two of these small, and the 3rd large. If you make all values large the app may become very slow.
The wavelengths are interpolated between λ1 and λn.
The source points are interpolated between -radius and +radius of the source surface.
There are two modes for setting the angle of the rays:
- When the ‘Aim at Pupil’ is off the angle of the rays are interpolated between -θ and +θ where theta is controlled by the fan angle slider. In this mode rotating the source surface will change the direction which the rays are aimed.
- When the ‘Aim at Pupil’ is on, the rays are aimed at the system’s Entrance Pupil. In this mode the fan angle slider actually controls how far apart the rays are on the entrance pupil. So at maximum value the rays reach the edge of the entrance pupil. Note that entrance pupil calculation are currently only valid for axial systems.