Search

In this paper, a cost-efficient distributed fiber optic measurement system based on Rayleigh scattering is presented. The distributed digital incoherent optical frequency domain reflectometry (I-OFDR) method is developed for detection of significantly large strain in the range from 3 % up to 10 % as required by end users. For this purpose, a vector network analyzer used in the I-OFDR is replaced by a compact and cost-effective digital data acquisition system. This digital emitting/receiving unit enables the recording of the complex transfer function carrying information about the local deformations along the entire sensing fiber. [ABSTRACT FROM AUTHOR]

Possibility of post-fabrication doping of commercial PMMA fibers using well-known solution doping technique is presented. The cladding of 1 mm PMMA fiber is doped with Rhodamine B with the help of methanol-mediated diffusion of the dye molecules into the fiber material. Doping of the fiber core was not possible even at extended doping times. The proposed method represents rather simple and cheap way for preparing custom cladding-doped POFs with high flexibility of dopant choice and fiber length. Produced cladding-doped fibers have potential for various sensing or lighting applications. [ABSTRACT FROM AUTHOR]

Application importance of ionizing radiation has been growing steadily over the last decades. Extensive utilization of ionizing radiation generates demand for development of suitable monitoring techniques. Radiation monitoring systems based on optical fibers offer several key advantages such as small footprint, possibility of remote and real-time measurement as well as electromagnetic immunity. In this contribution, we investigate radiation-induced attenuation (RIA)-based sensing with perfluorinated polymer optical fibers (PF-POFs). The RIA response of two commercial PF-POFs is assessed in a low dose region and performance and limitations of the system are discussed. The concept represents a potential high-sensitivity, low-cost and easy-to-use on-line radiation monitoring system with distributed detection capability. [ABSTRACT FROM AUTHOR]

Systematic investigation of annealing behavior of drawn PMMA fibers was performed. Dynamics of annealing process were measured under different environmental conditions by fiber longitudinal shrinkage monitoring. Process was found to follow stretched exponential decay function indicating heterogeneous nature of underlying molecular dynamics. Consequences of fiber annealing for climatic stability of polymer optical fiber-based sensors are discussed, emphasizing importance of fiber controlled post-fabrication annealing. Dependence of induced fiber shrinkage on annealing time, temperature and fiber drawing conditions is investigated and interpreted. In addition, strong influence of humidity on annealing process was observed, which was not recognized in previous studies. This further highlights role of fiber post-fabrication thermal treatment with respect to intended operating conditions. [ABSTRACT FROM AUTHOR]

We present the fabrication and characterization of a polycarbonate (PC) microstructured polymer optical fiber (mPOF) and the writing of a fiber Bragg grating (FBG) in it to obtain a polymer optical FBG sensor. The manufacturing process of the PC mPOF consists of multiple consecutive stages, such as casting of polymer granulates into a solid rod, machining and drilling of a 3-ring hexagonal lattice of holes into it, and finally drawing into fiber. We demonstrate that the obtained PC mPOF is photosensitive and FBGs can be conveniently inscribed into it, thereby enabling FBG-based temperature and strain sensing. The PC optical fibers are for some applications an attractive alternative to conventional materials used in POF fabrication, such as polymethyl methacrylate (PMMA). In general, PC can be used at temperature up to 120 °C and breaks at considerably higher strains than PMMA. [ABSTRACT FROM AUTHOR]

We propose to use focused femtosecond laser pulses to inscribe scattering damage in the core of polymer optical fibers for interrogation as quasi-distributed sensor points by optical time domain reflectometry. Fiber bend measurement is demonstrated on off-center inscribed sensor points and absolute temperature measurement is presented by evaluation of the constant backscatter intensities from the inscribed structures relative to temperature-dependent Rayleigh scattering. Application possibilities and limitations of this new approach are discussed. [ABSTRACT FROM AUTHOR]

This paper reports about the EU project i-Protect in which fibre optic sensors for measuring heart rate, respiratory rate and skin temperature are being developed. The sensors and monitoring units are integrated into underwear and are communicating wireless via body area network and communication unit with the rescue command centre. All sensors can be removed from the underwear to allow washing the textile. [ABSTRACT FROM AUTHOR]

Optical switches, OTDR devices and POF based fiber strain sensors have been connected in order to investigate the sensitivity to strain and quality of the signal regarding the limiting influence of the switches additional Fresnel reflexions. [ABSTRACT FROM AUTHOR]

The Brillouin gain spectra (BGS) in perfluorinated graded-index polymer optical fibers (PFGI-POFs) are characterized at 1.32 and 1.55 μm. Three kinds of PFGI-POFs with the same core diameter but fabricated by different manufacturers are tested. For all the PFGI-POFs, the Stokes power measured at 1.32 μm is higher than that at 1.55 μm due to the lower propagation loss, but significant difference in Stokes power is observed among the three. Based on the measurement by optical time-domain reflectometry, we show that the actual propagation loss of the PFGI-POFs plays a crucial role in observing BGS. [ABSTRACT FROM AUTHOR]

This paper reports on a fibre optic sensor for heart rate measurement which is developed within the framework of the FP7 EU project i-Protect. Goal is integration of the sensor into personal protective equipment Two different sensor prototypes based on polymer optical fibre (POF) were developed. One is based on long period gratings in microstrutured POF and the other one is based on macrobending effects in POF. [ABSTRACT FROM AUTHOR]