differents values between Footprint and PARR operand

  • 26 February 2024
  • 2 replies


We have different values  between Footprint and PARR operand ( see below):

  •  on footprint : Max radius  = 0,1241
  • in Merit Function : PARR Surf 23 = 0.120

how can we get the  value of the footprint in the Merit function?

Thanks for your help,



Best answer by David.Nguyen 26 February 2024, 15:32

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PARR stands for paraxial radial ray coordinate. PARR uses paraxial rays. In contrast, while its not specifically mentioned, I believe the Footprint diagram uses real rays. Could you try with REAR, real radial ray coordinate, instead of PARR and tell us whether it makes a difference?

Moreover, you might be interested in that thread as well, where I wrote a user-defined operand (UDOC) to read the actual min/max values from a Footprint Diagram:

The remark from @Mark.Nicholson still applies though, i.e. if you can get away with measuring the footprint with a native operand thanks to the symmetry of your system, then it will be an overkill to read the Footprint Diagram values via a user-defined operand (executing the UDOC adds some overhead to the optimization).

Take care,



thanks a lot David. I change and put REAR. Nows the value between lens data editor( column semi diameter), values in foot print and in Merit function are the same = 0,120.