One could do an experiment to show whether the PLD method or the Theta method will give a more precise prediction about the diffraction pattern. If the slit width (d) can be made less than 100-50 micrometers, the screen's distance (L) can be placed somewhere from 4 to 10 meters, and the laser wavelength (w) should be from 600 to 700 nanometers, then we could have a view to the visible and a measurable difference.
