Diffraction of Diode Lasers, Physics 3901, Fall 04

A helium-neon laser with standard wavelength 632.8 nm was used with a single slit to determine its width. With a distance of 1.94 meters from the wall, a distance of 0.029 meters from the maximum to first minimum was measured. This corresponds to a slit width of a = 42.2 micrometers by the single slit calculation. At the same screen distance, measurements of 0.0298 m for the red and 0.0244 for the green diode laser were made. These measurements correspond to 652nm and 532 nm for the red and green lasers respectively. Investigation with the double slit gave a slit separation of 2.0 x 10^-4 m and 650nm and 530 nm for the red and green wavelengths respectively. Use of a 600 lines/mm diffraction grating gave 653nm and 531nm for the red and green.

Various methods were explored for moving the second order diffraction grating maximum across a silicon light detector to get a plot of the light distribution with distance. The plots below for the helium-neon laser and red diode laser were obtained by moving the light detector through the diffraction maximum by hand. The shapes were then fit to a gaussian curve.

Experimenters: Amber Bishop, Hoang Dau, Tatjana Tomovic and Mike Herrera(not shown).