Using Pfundt's Method to find the index of refraction of transparent solids and liquids had been part of the intermediate laboratory repertory for decades. The advent of diode lasers made it quick and easy to set-up so students could focus on the theory behind the observed pattern and on analyzing and reducing uncertainties using multiple measurements. Depending on the objectives of the particular intermediate laboratory class and students' prior laboratory experience, this laboratory can easily be used for either a conceptual approach, or as a robust exercise in error analysis which provides insight to the role of measurement uncertainties. Various techniques for measuring the ring diameters have been explored by different instructors at our institution and an overview of these, together with analysis of typical data is presented.