how to measure squareness with a square (get an actual measurement)

[nova_robotics]

The colour of light? Nah. I totally agree with you on that. In order for the gap to become a point source it has to be on the order of a wavelength. It's really cool to think about though.

Now you got me thinking. What about clicking your multimeter to the capacitance function and putting a sheet of cellophane (or something) on your square?