Absolute distance metrology with frequency sweeping interferometry

摘要

Coherent interferometric absolute distance metrology is one of the most interesting techniques for length metrology. Without any movement, measurements are made without ambiguity, by using either one or several synthetic wavelengths resulting from the beating of two or more wavelengths (multiple wavelength interferometry) or, in the case of frequency sweeping interferometry (FSI), from a frequency sweep. FSI-based sensors are relatively simple devices and can fulfill an important role on the metrology chain, even for very small relative errors in the context of demanding applications (such as space). In addition, their parameterization flexibility allows tradeoffs to be performed, either technology driven or application related. In the context of the ESA/Darwin technology package, we implemented a FSI sensor composed of a mode-hop free frequency sweep external cavity diode laser, a high finesse Fabry-Perot interferometer to measure accurately the frequency sweep range, homodyne detection and data processing. In this paper, we present in detail the uncertainty budget for the FSI final uncertainty, give examples of different parameterizations, and demonstrate and evaluate sensor performances and robustness for the high precision optical metrology for the Darwin satellite configuration.