My optical setup has fiber laser output which collected and collimated by collimating lens and then focusing lens(Plano convex) . And then, I have system of Galvano mirrors (Maximum scanning angle ±22° ) for 2D scan over square field area. So, I am observing spot diameter for center and corner position of square field area(250*250 mm^2) using feature Paraxial gaussian beam. Here, I am attaching Spot diagram and paraxial gaussian beam data. Please note that, configuration 1 is for spot in center position and configuration 9 is for one the corners position. I am also attaching 3D layout for better visualisations.
I get same value for laser spot diameter center position as well as corner position of image plane. Theoretically I should get larger value (and non-circular shape) of corner points than center because path length for beam increase for beam as shown in spot diagrams. But paraxial gaussian beam data shows similar value for configuration 1 and 9(in fact for all). I would be grateful if anyone can help me to understand my mistakes.