Numerical evaluation of the intensity distribution of a multiple-beam Fizeau fringe in reflection at finite number of beams collected

We modified the intensity distribution formula in multiple-beam reflected system produced at infinite number of beams collected to be a function of finite number of beams collected. From the modified equation, a numerical process was performed to find a finite number of beams value that gives the same intensity at infinity. We claim that 30 beams are enough to produce the intensity distribution same as if infinity number of beams are collected. Our deductions were verified by numerically evaluating the intensity distribution of a multiple-beam Fizeau–Tolansky interferometer with a wedge angle = 0.0003164 rad using ray tracing at 30 number of beams collected and the results of simulation are consistent. The consistency signifies that using 30 instead of infinity number of beams collected in ray tracing for the intensity distribution evaluation may reduce the time drastically.