An optical system for cryogenic temperature measurements

Ciotti, Marco; Nardelli, Vitor C.; Caponero, M.; Felli, F.; Lupi, C.; Ippoliti, Luigi

doi:10.1088/0964-1726/16/5/024

Cited by 14 publications

(5 citation statements)

References 5 publications

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“…The optical fiber temperature sensor usually has a resolution of 0.3 K in the temperature range of 20-120 K [19]. Ciotti et al [20] claimed a temperature measurement resolution of 0.02 K. However, its sensor response time is slow, on the order of 1 s. The WGM sensor has a quick response. For instance, the time constant of a silica microsphere 80 μm in diameter is only 0.03 s. As an optical fiber sensor, the WGM sensor can be certainly applied to a cryogenic temperature range on the order of 10 K, although the current infrastructure cannot realize such a low temperature.…”

Section: Resultsmentioning

confidence: 99%

“…However, this kind of sensor is not cost-effective, and the resolution is limited by the fluorescence emission intensity and contrast of decay time in cryogenic temperatures. Ciotti et al [20] have studied a photo-imprinted Bragg grating fiber optic cryogenic temperature sensor. On illuminating the fiber with a broadband source of light, a narrow band is reflected by the grating at the Bragg wavelength.…”

Section: Introductionmentioning

confidence: 99%

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Whispering-gallery mode silica microsensors for cryogenic to room temperature measurement

Rossmann

Guo³

2010

Meas. Sci. Technol.

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Optical resonance shifts are measured against a wide range of temperatures from cryogenic to room temperature for silica microspheres operating at whispering-gallery modes. The sensor head microsphere is coupled to a fiber taper and placed in an insulated cell where the air temperature first cools down to below 110 K and then rises steadily and slowly. The transmission resonance spectrum of a distributed feedback laser at 1531 nm exciting the microsphere-taper system is monitored and recorded for every 1 K temperature increment. The resonance wavelength shifts against the temperature changes are analyzed. Several microspheres with size from 85 to 435 μm are tested. No significant dependence of the sensor sensitivity is seen with the sphere size. A cubic dependence of the wavelength shift versus the temperature is least-squares fitted. The measured sensitivity increases from 4.5 pm K −1 to 11 pm K −1 with increasing temperature in the test temperature range, and this behavior is consistent with the temperature dependence of the sum of thermal expansion and thermo-optic coefficients of silica material. The resolution of the sensors with the current instrument could reach 3 mK.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Whispering-gallery mode silica microsensors for cryogenic to room temperature measurement

Rossmann

Guo³

2010

Meas. Sci. Technol.

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“…Therefore, metallization is proposed to shield RGs from thermal and mechanical loads and also provide protection from environmental moisture by hermetic encapsulation [16]. Currently, many techniques have been considered to realize metallic coating of an optical fiber, such as casting [17,18], physical vapor deposition (PVD) [16,19,20], electroless plating [21,22], and electrodeposition [19,20,22], but constraints such as coating thickness and processing parameters are also associated with these options. Casting cannot be used, since using metals with a high melting point in the casting would bring about the destruction of the gratings and cause high thermal stress.…”

Section: Introductionmentioning

confidence: 99%

Fabrication and thermal characteristics of multilayer metal-coated regenerated grating sensors for high-temperature sensing

2013

Smart Mater. Struct.

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Health monitoring of components operating at high temperatures requires the development of new sensors to measure temperature and deformation. A regenerated grating (RG) sensor with titanium (Ti)–silver (Ag)–nickel (Ni) multilayer coatings is fabricated by magnetron sputtering and electroplating processes. Optical and thermal tests are performed to evaluate the characteristics of the Ti–Ag–Ni-coated RG sensor. The shapes of the reflection spectra for the RG are slightly affected by the metallization process. The Ti–Ag–Ni-coated RG sensor exhibits a higher sensitivity than that of the bare RG for temperatures up to 600 ° C, with good repeatability and stability. It is verified that the titanium coating can achieve good adhesion to the optical fiber and that the silver coating is suitable as a conductive layer for electroplating. An analytical model for the axial strain and radial strain in a multilayer metal-coated optical fiber is proposed. Comparisons of the experimental results and the theoretical predictions show a good agreement below 250 ° C. These results indicate that multilayer metal-coated RG sensors can be successfully fabricated by combining magnetron sputtering with electroplating and provide great potential for high-temperature sensing.

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“…Tests in both liquid helium and helium vapours were performed, using a Cernox CGR resistive thermometer to obtain reference temperature measurement. The wavelength shift of the sensor reflection spectrum with different metal coatings together with temperature changes of the resistive thermometer for several cycles were reported in a previous paper [7].…”

Section: Sensitivity Comparisonmentioning

confidence: 70%

Metal coating for enhancing the sensitivity of fibre Bragg grating sensors at cryogenic temperature

Lupi

Felli

Ippoliti

et al. 2005

Smart Mater. Struct.

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Fibre Bragg grating (FBG) sensors that are immune to electromagnetic interference could advantageously perform cryogenic temperature monitoring in superconducting magnetic fields, but their intrinsic temperature sensitivity is quite poor and must be enhanced. In fact, the low thermal expansion coefficient of silica limits the temperature sensitivity of bare FBG sensors at cryogenic temperature. In this paper the possibility of improving the temperature sensitivity of FBG sensors by metal coating is investigated. Specifically, zinc and copper coating depositions are performed by the traditional electrowinning process, after aluminium pre-coating of the sensor. Coated FBG sensors are inspected by both optical and metallographic techniques. SEM metallographic investigations show that a homogeneous deposit is obtained, with good metal adhesion to the FBG sensor. Optical testing shows that the optical properties of the coated FBG sensors are slightly affected: aluminium pre-coating produces appreciable modification of the diffraction spectrum in both peak width and peak shift, while zinc coating produces a moderate peak shift and copper coating just enlarges the peak width. Results presented in this paper show that both metals appreciably increase the temperature sensitivity of the FBG sensors. Zinc coating provides the highest sensitivity and high-resolution temperature measurements are possible at temperatures as low as 15 K.

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An optical system for cryogenic temperature measurements

Cited by 14 publications

References 5 publications

Whispering-gallery mode silica microsensors for cryogenic to room temperature measurement

Whispering-gallery mode silica microsensors for cryogenic to room temperature measurement

Fabrication and thermal characteristics of multilayer metal-coated regenerated grating sensors for high-temperature sensing

Metal coating for enhancing the sensitivity of fibre Bragg grating sensors at cryogenic temperature

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