Accurate remote distance sensing by use of low-coherence interferometry: an industrial application.
An apparatus for accurate remote distance sensing based on fiber-optic low-coherence light interferometry has been designed for molten glass level measurement. We demonstrate operation of the meter in an adverse industrial environment with <20-mum resolution (standard deviation) within a 20-mm range with the sensing head placed in an oven at ~800 degrees C. In laboratory conditions we were able to measure with 3-mum resolution, which could be improved to submicrometer level by optimization of a reference arm of the interferometer and detection electronics.