Advanced laboratory exercise: studying the dispersion properties of a prism pair

A laboratory exercise has been developed in the frames of a new course called "Advanced undergraduate laboratory in femtosecond optics", which aims to study the dependence of the dispersion of a prism pair on the positions of the prisms. For the dispersion measurement we chose a relatively simple technique, called white light spectral interferometry. The prism pair consisting of two identical fused silica prisms was placed in the sample arm of a Michelson- interferometer illuminated with a tungsten halogen lamp. The interferograms were observed with a low resolution spectrometer in order to have a wide detection range (200- 1100 nm). Measurements were performed by adjusting the optical path length in the second prism. The data was evaluated with the cosine-function fit method. Using the formalism of Fork the phase derivatives were theoretically calculated as well. The dependence of the dispersion coefficients on the displacement of the second prism agree well with the measurements. Using white light is advantageous as its broad wavelength range facilitates the retrieval of the spectral phase with high precision in a wide range. Furthermore, white light sources are relatively low-cost and safe in contrast to ultrashort laser sources. © COPYRIGHT SPIE