LASER-DOPPLER VELOCIMETRY USING A BULK OPTIC MICHELSON INTERFEROMETER- A STUDENT LABORATORY EXPERIMENT

The Doppler frequency of reflected light from a moving mirror is measu red using a Michelson interferometer and a low cost spectrum analyzer. The experimental data for the Doppler frequency are in agreement with the calculated theoretical values with a standard percent error of 0. 54%. The concept of optical mixing of a phase-modulated signal with th e Doppler signal is presented, with a derivation of the resulting dete cted signal power, using the small phase modulation amplitude approxim ation. An experiment is described using laser Doppler velocimetry to h eterodyne the Doppler signal with an acoustic wave. The experiment pro vides a good illustration of the Doppler effect, spectral analysis, an d principles of optical mixing and interferometry in an advanced under graduate laboratory.