I think in the file you saw, paraxial lens was there to simplfiy the design at the very early stage; just to have some idea about what sort of lens power is required to collimate. In reality, you will need to substitute the real lens later on.
OEGAwP?F G@Zi3 5 For your second question, you shall check your light source illumination angle and see if majority of the rays hitting at the surface is beyond the critical angle. You may also zoom in the layout to see if some rays do emerge from this surface/lens cos in ZEMAX, if there is no objects ahead of the direction where the rays are travelling to then ZEMAX will normally terminate the ray tracing.
qXW2a'~ /[#{#:lo2 Not usre of the lens or the surface has any coating assigned, if so, you better tick the option of "Use Polarization" and "Split Ray" in order to see some effects that are only accounted under polarization analysis.
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