The goal of this project was to develop an apparatus to measure the coherence length of the light waves produced by different lasers.The coherence length is the distance over which two interacting waves maintain a constant relative phase.The method selected to achieve the goal of the project was to introduce the laser light into a modified Michelson interferometer arrangement while observing and measuring the resulting interference pattern. This pattern can be interpreted in terms of the properties of the laser light from which the pattern was produced, including, it was predicted, its coherence length. In order to characterize the apparatus and develop a means of interpreting the interference patterns, two different lasers were used: a red diode laser taken from an inexpensive laser pointer, and a red He-Ne laser. As part of this project the quantum eraser phenomenon and bandwidth of the diode and He-Ne lasers were also investigated. The project is continuing an investigation of the utility of the apparatus for coherence length measurements.