Design of a Simple Laser Interferometer for Vibration Sensing

Vibration sensing by optical means has two inherent advantages: large mechanical bandwidth and contactless operation. There are available commercial devices which perform these type of measurements with stunning performance, but typically at the cost of bulky equipment and considerable prices. This stems from the fact that these equipment can perform absolute measurements under a wide variety of experimental conditions. In certain non-destructive testing (NDE) applications, however, the displacement of the surface of an object needs to be measured under known conditions (such as surface flatness and sensor placement), and absolute magnitude measurements (other than time-of-flight) are not needed, hence, a much simpler device might be utilized. In this project, we would like to develop a simple laser interferometer by the use of a beamsplitter, a mirror, a laser diode, and a photodiode with the associated electronics. A mechanical housing to host all components with reasonable accuracy and adjustment features is to be designed as well. The designed device is expected to resolve issues of price and size with the conventional measurement equipment.