We have developed an experimental apparatus that makes it possible for stud
ents to make detailed quantitative measurements of the Fresnel reflection c
oefficients for the reflection of light from a plane interface. The experim
ent is made possible by the linear polarization, and impressive power stabi
lity, exhibited by visible and near-infrared diode-laser modules, and it ha
s been a very effective addition to our sophomore electromagnetism laborato
ries. (C) 1999 American Association of Physics Teachers.