Hi Steven, 

If you look at the Field Data Editor, you can see that there are Vignetting Factors for Field 2 and Field 3.  Vignetting Factors intentionally make the rays for different fields to not overlap at the Stop location.  If you remove the VDY, VCX, & VCY you will see the rays intersect at the Stop location:

@David.Nguyen The file is the first microscope after the Boge design in the Libraries > Design Templates.  This used to actually have a name in Zebase but now that it’s in Design Templates, the file is loaded as a temporary file so you can’t easily find it except going through the Design Templates.

Hey David,

Rather than thinking of “overlapping fields at the Stop”, remember that Vignetting Factors are a tool that should only be used early on in the design during optimization and final analysis should remove Vignetting Factors and ensure all surfaces have a hard aperture (this is what the Design Lockdown does).  A designer would use the Vignetting Factors early in the design if they know there will be a limiting aperture for off-axis fields because of size or geometry constraints.

Vignetting Factors is an approximation for early analysis to ensure that all 4 marginal rays make it through the system since a few Optimization operands rely on the marginal rays, but this approximation uses an ellipse rather than the actual Cat’s Eye you get for vignetted off-axis fields.  To get the actual analysis of a final design, the full beam footprint should be used for each field.

HI @David.Nguyen  @MichaelH  ,thank you, guys.