ABSTRACT
Interest in interferometry as a measurement tool arises predominantly from the inherent measurement resolution aorded by interference of light: visible and near infrared light, with wavelengths in the region of 0.4 μm to few μm, makes an excellent measuring stick with which we can measure some characteristic length, or change in length, of the optical paths in the interferometer. Appropriate analysis of the interference yields subwavelength resolution and accuracy, with nanometer scale measurements commonplace. Optical techniques have a number of oen cited advantages that can be particularly relevant for challenging measurement environments. In addition to measurement resolution, these include inherent safety, good noise immunity, and ease of sensor multiplexing. Optical measurements can also oer an advantage through noncontact measurements. is is exploited in cases where it is important to eliminate mass loading of the structure under observation, or for use in harsh environments in which a contact sensor lifetime would be limited.
