Photodetection of Diffraction Pattern, Physics 3901, Fall 02

A photodetector was mounted on a cart and moved through the light from a helium-neon laser which had been diffracted by a single slit.

The purpose of this lab was to create a graph of the diffraction pattern created by a laser through a single-slit diffraction grating. The grating was set up on a stand, and the laser placed on a lab jack so the beam went directly through the slit. Next, a light sensor was securely taped onto a cart, which was placed on a low-friction track and adjusted so that the sensor would travel directly through the diffraction pattern along the track. The light sensor was connected through the computer, and set to graph the data on the screen. A small push to the cart resulted in a speed that was too fast for the computer to graph accurately. So a string was attached to each end of the cart, and small masses added to each end until a slow, fairly constant speed was achieved. One large peak and two smaller peaks were visible, but the second peak on each end were not, possibly due to the inaccuracy of the laser projection field onto the sensor, or to a low sensitivity level of the light sensor.

Experimenters: Theresa Crider-Cox, Steven Gerber