Optical time domain reflectometry

Other near-IR applications which use similar pulse and phase instrumentation as used in lifetime measurements include optical time-domain reflectometry(25) and photon migration in tissue. 26 ... 

G. Ripamonti and S. Cova, Optical time-domain reflectometry with centimeter resolution at fW sensitivity, Sec. Lett. 22, 818-819(1986). 

FOTDR frequency optical time domain reflectometry... 

Balageas et al. [107] and Bocherens et al. [108] describe the use of optical time-domain reflectometry (OTDR) and FBG to detect impact damage in GFRP sandwich specimens. The optical fibers were embedded in the sandwich core at various depths (Figure 16.49). The principle of the detection method is that deformation and damage due to impact leave areas of permanent strain around the impact zone. The OTDR and FBG methods were employed to detect such changes in comparison with the... 

Parameters to be varied by the measurand are the intensity, the wavelength or phase, and the polarization state of light. Additionally used is, by means of optical time-domain reflectometry (OTDR) technique, the measurement of the travel-time of a light pulse launched at one fiber end and backre-flected at markers. From measurement of the time of transit, the shortening or extension of the optical path length (contraction or extension of the sensor fiber) can be assessed. However, any effects influencing the fiber can be located. It should be noted that a considerable number of fiber optic sensor types has been created in the past decades for measurement of almost all physical, and a lot of chemical, quantities. 

The distributed signals can be measured and spatially resolved by an optical time-domain reflectometry technique. An optical time domain reflectometer is based on the measurement of backscattered light attained from a light pulse propagating through an optical fiber. Light is backscattered because of inhomogeneities and impurities... 

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