We do a low-tech version of the diffraction pattern of a single or double slit by using a shaft
encoder and phototransistor. The transistor is housed in a black plastic block with an
entrance slit on the front. This block is connected to a shaft encoder and a spring.
When you slide the block through the diffraction pattern (about 3 inches of travel) the shaft
encoder turns so in one pass you have light amplitude vs distance (well, angle, which is
easy to convert to distance).
This is stuff we did ourselves, hardware and software. The interface is a BIB (see my home
page for details), so the experiment can be run on a laptop through the printer port.
Mike
Mike Moloney, Dept of Physics & Applied Optics, Rose-Hulman Institute of Technology