Absolute Displacement Measurement Research Articles

Fibre optic interferometric sensor based on source coherence synthesis by dynamical spectral filtering of a superluminescent source

Interferometric sensors based on source coherence synthesis have been reported for measurement of quasistatic parameters. An absolute sensing technique has been demonstrated based on fringe visibility modulation using a frequency modulated laser. In this Letter, a technique is described which allows to perform absolute displacement measurements in the range from tens to several hundreds of micrometers. It is based on dynamical spectral filtering of a superluminescent source which provides frequency modulation amplitudes up to 3000 GHz. The principle is described and experimentally verified for displacement measurement.

Applications of semiconductor and solid state lasers in optical sensing.

Semiconductor laser and diode-pumped solid state laser techniques are reviewed concerningremote sensing and precision instrumentation. First, the basic principles of remote range detectionusing these lasers are compared for a pulse method, intensity modulation method, randommodulation method, and frequency modulated (FM) heterodyne method. These methods are appliedto lidar (laser radar) for detecting the spatial distributions of atmospheric aerosolparticles. The FM heterodyne method is-capable of accurate measurement of both absolute rangeand displacement when widely tunable diode lasers are used. As potential applications ofdiode-pumped solid state lasers, a coherent lidar and a space lidar as well as an interferometerantenna of gravitational waves are introduced.