PHASE MEASURING METHOD AND APPARATUS FOR MULTI-FREQUENCY INTERFEROMETRY

摘要

The invention provides a novel method for absolute fringe order identification in multi-wavelength interferometry based on optimum selection of the wavelengths to be used. A theoretical model of the process is described which allows the process reliability to be quantified. The methodology produces a wavelength selection which is optimum with respect to the minimum number of wavelengths required to achieve a target dynamic measurement range. Conversely, the maximum dynamic range is produced from a given number of optimally selected wavelengths utilised in a sensor. The new concept introduced for optimum wavelength selection is scalable, i.e. from a three wavelength system to a four wavelength system, from four wavelengths to five, etc.