I want to set a Grid Sag lens in non-sequential mode.I am not familiar with this mode so  I think I may set some wrong basic parameters.

I want to set a 40mm*40mm metalens in this mode,so the front and back radius should be infinity.And I set the thickness 1mm.Other parameters are 0.

But sometime it tells me that there is geometry erro,if I run “ray trace”,there is erro,too.

Sometime it show me a metalens with a thickness of 5e+5mm.I got no idea where did this  super-thick metalens come.

I try to adjust some parameters but useless.I don’t know how to fix this problems.I would appreciate it a lot if someone can help me.