Wyniki wyszukiwania - BazTech

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Długookresowe siatki światłowodowe jako czujniki drgań w materiałach kompozytowych

Domański A. W., Czapla A., Prokopczuk K., Poczęsny T., Bock W., Woliński T. R.

Pomiary Automatyka Kontrola

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2010

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R. 56, nr 7

809-811

PL

Użycie czujników opartych na siatkach LPFG otwiera nowe możliwości diagnostyczno-pomiarowe, takie jak na przykład monitorowanie w czasie rzeczywistym stanu zużycia materiałów kompozytowych. Dzięki zatopieniu włókna w takim materiale możliwe jest monitorowanie drgań i naprężeń nie powodując przy tym znaczących zmian parametrów eksploatacyjnych i wytrzymałościowych kompozytu. W prezentowanej pracy przedstawiono zastosowanie siatek LPFG do detekcji deformacji geometrycznych oraz przeprowadzono badania porównawcze czujników światłowodowych z siatkami LPFG zatopionych w materiale kompozytowym z tego samego typu czujnikami pracującymi w swobodnej przestrzeni.

EN

Vigorously growing fiber-optic technology allows constructing sophisticated sensors to monitor vibrations and stress. Application of long period fiber gratings (LPFG) enables making an optical fiber sensitive to various external parameters caused by longitudinal or transverse stress changes in material. An additional advantage of sensors based on LPFG is the measuring part insensitivity to electromagnetic disturbance and lack of electric noise and interference emission. The manufacturing of optical fiber with LPFG is based on precise heating or exposition a part of the fiber to ultraviolet radiation thereby inducing a periodic change of the refraction index along the fiber core. As a result, the transmission spectrum of LPFG is characterized by a number of attenuation bands induced by coupling between the elementary mode propagating in the core and cladding modes. Location of the attenuation bands in the LPFGs transmission spectrum is dependent on external physical factors. This paper presents application of LPFG to geometric deformation detection. The use of sensors based on LPFG opens new diagnostic and measuring possibilities like real-time monitoring of composite material wear. Due to sinking the LPFGs in this material, it is possible to monitor the vibrations and stresses without causing significant changes in operational performance and durability of the composite. The paper also presents a comparative study on LPFGs sunk in composite material with the same type of LPFGs operating in free space.

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Towards tuning of thermal sensitivity of the long period fiber gratings using a liquid crystal layer

Czapla A., Bock W., Mikulic P., Woliński T.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2010

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Vol. 58, nr 4

503-508

EN

A high-efficiency thermal tuning filter based on a long-period fiber grating (LPFG) combined with a low-birefringence liquid crystal (LB LC) cladding layer is presented. Two types of LPFGs were studied and compared: the LPFGs based on a standard telecommunication fiber produced by an electric arc technique, and the LPFGs based on a boron co-doped fiber written by a UV technique. Both types of LPFGs when enhanced with an external LB LC layer exhibit two different temperature sensitivities, which depend on the temperature range of operation. For the LPFGs based on standard telecommunication fiber we can conclude that the presence of the LB LC cladding increases the thermal tuning efficiency by more than one order of magnitude over the value for the LPFGs in air. In the case of the LPFGs based on the boron co-doped fiber we discovered it is possible to obtain either a temperature-independent attenuation band or the attenuation bands with high temperature sensitivities, just by careful choice of the order of the cladding mode and the operating wavelength.

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Oleje dla naturalnych czynników chłodniczych

Puhl C., Bock W.

Chłodnictwo i Klimatyzacja

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2007

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nr 3

72-77