Abstract
Optical interferometry, amongst other techniques such as capacitive and the read back signal method, is a well established technique for the measurement of small displacements [1]. Previously, heterodyne interferometry [2] and phase-shifting interferometry [3] have been used to make high resolution measurement of such small displacements. However, these existing methods are generally only feasible for low speed measurement applications. A polarisation interferometer has been designed and built to measure dynamically the flying height down to near-contact.
