How to draw incoherent light intensity ?

This is a two-lens imaging processing system.

I want to draw incoherent light intensity in 2D system.

Use lamda=632nm，A=5mm，B=7mm，f1=10cm，f2=8cm

sf(x,y) = rect(x/A)rect(y/B).

clc
clear all

lamda = 632e-9;
k = 2*pi/lamda;
A = 5e-3; B = 7e-3;
f1 = 0.1; f2 = 0.08;

Sf(x,y)=rect(x/A).*rect(y/B);

please help me

thank you!