Paraxial Lens

The Paraxial Lens is an ideal thin lens surface with separate X and Y focal lengths. The defining parameters are:

Parameter #	Description	Face Name	Face #
1-2	The X/Y Half Widths. Make positive for a rectangular shape, negative for an elliptical shape.	All Faces	0
3-4	The X/Y direction focal length, measured in air, in lens units.	All Faces	0

This object may be placed in air, or be fully or partially immersed within a homogeneous or gradient index medium. No adjustment of the optical path length or phase of the ray is made during refraction, so no attempt at estimating the correct phase of the ray is made. No attempt is made to compute the polarization effects of refraction through this idealized part. If polarization effects are important, this object should be used with caution, especially if the ray angles on either side of the lens are large with respect to the normal.

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