Method

I ran xdesktopwaves with the command line

xdesktopwaves -rain 0 -root -opaque -nice 19 
 -watercolor black -skycolor lightblue -lightcolor white
 -viscosity 1 -wavesbymouse -wavesbywindows -quality 8

Some of these options were probably redundant. Oh well.

Waves produced by xdesktopwaves with these settings don't travel through windows, so I used windows to make my double slit. I switched to an empty desktop, removed all of my panels and such, and opened four xterm windows. Three of them I made one character wide, varying heights, and arranged so that two narrow apertures remained for wave transmission. The fourth I made slightly wider, so I could still type at it, and short vertically; it was positioned at the top left of the window.

Toggling the ``vertical maximize'' on the fourth xterm produced a pulse of plane waves travelling to the right. These plane waves passed through the slits and interfered on the right half of the screen.

I used a command-line screenshot grabber to take images. Since I controlled the screenshot grabbing from one of the windows on screen you can see in the data what I did and how long it took.