ON THE FORMATION OF WHITE-LIGHT INTERFERENCE-FRINGES

We describe an experiment in which the white-light interference fringe s appearing at the output of a Michelson interferometer are observed t hrough a spectrograph. In this manner the relative positions of monoch romatic interference fringes come into sight and it allows a better un derstanding of the formation of the white-light fringes. A simple mode l is described for determining the shape of the spectrally resolved wh ite-light interference fringes. An expression for the relationship bet ween the slope of the fringes and the arm length difference of the int erferometer is derived and is demonstrated experimentally. In addition , an intuitive explanation based on this experiment is given for the w ashing out of the white-light fringes. (C) 1998 American Association o f Physics Teachers.