Simultaneous Measurement Of Temperature Research Articles

Simultaneous measurement of water temperature and salinity using Raman spectroscopy

We present a method to simultaneously determine water temperature and salinity, which uses a pulsed excitation laser and a three-channel Raman spectrometer. The method relies on the systematic dependence of the Raman OH stretching band on temperature and salinity, and is compatible with LiDAR techniques. We have measured the variation of the OH stretching band in two seawater samples and a NaCl solution, and constructed a linear mapping between signal ratios derived from the three spectral channels and the temperature and salinity of each sample. For the natural seawater this approach has been determined by cross-validation to have a predictive accuracy of ±1.6 PSU and ±0.5 °C.

Simultaneous bending and temperature measurement based on a superimposed fiber grating sensor

A compact and novel superimposed fiber grating (SI-FG) sensor for simultaneous measurement of temperature and bending based on UV-induced FBG cascaded with a multimode fiber (MMF) embedded ultra-long period fiber grating (MMF-EULPFG) has been proposed and experimentally validated. The MMF-EULPFG acts as a temperature and bending sensing unit and was fabricated by periodically splicing a non-UV-non-photosensitive MMF and a UV-photosensitive single-mode fiber (SMF) which is so called cleaving-splicing method. Due to the periodic refractive index modulation, the 6-period SMF-MMF structure based MMF-EULPFG with a total length of 2.7 mm forms transmission spectra with a −17 dB dip. The proposed SI-FG sensor exhibits high bending and temperature sensitivities of 17.096 nm/m−1 and −0.238 nm/℃, respectively. The UV-induced FBG is fabricated in the initial segment of UV-sensitive fibers within EULPFG by UV exposure method. The dip of FBG transmission spectra also shows response to bending and temperature. By utilizing a matrix obtained from the experimental results, simultaneous measurement of temperature and bending can be achieved. Due to its compact structure and high sensitivity, the proposed novel SI-FG sensor can be used as a competitive all-fiber sensor for structural health monitoring and 3D-shape sensing.Index Terms: Optical fiber sensor, long period fiber grating, superimposed fiber grating, simultaneous measure.

1D interferometric Rayleigh scattering velocimetry and thermometry using VIPA

The work introduces a VIPA-based interferometric Rayleigh scattering instrument for tracer-free, simultaneous temperature and velocity measurements along a 1D volume. A virtually imaged phased array (VIPA) replaces the Fabry-Perot etalon conventionally used in interferometric Rayleigh scattering, allowing the extension of the technique from 0D (point or multi-point) to 1D. The Rayleigh-Brillouin spectrum is a function of pressure and temperature and can be used for temperature diagnostics in isobaric flows. A reference leg based on a Fabry-Perot (FP) etalon provides real-time monitoring of the laser wavelength drift during the experiment. The accuracy and precision of the measurements are estimated from measurements in laminar flows, and the technique is then demonstrated in a heated turbulent jet of air.

Simultaneous measurement of bidirectional magnetic field and temperature with a dual-channel sensor based on the whispering gallery mode

What we believe is a novel dual-channel whispering gallery mode (WGM) sensor for concurrently measuring bidirectional magnetic field and temperature is proposed and demonstrated. Two sensing microcavities [magnetic fluid (MF)-infiltrated capillary and polydimethylsiloxane (PDMS)-coated microbottle, respectively, referred as Channel 1 (CH1) and Channel 2 (CH2)] are integrated into a silica capillary to facilitate the dual-channel design. Resonant wavelengths corresponding to CH1 and CH2 mainly depend on the change in the magneto-induced refractive index and the change in the thermo-induced parameter (volume and refractive index) of the employed functional materials, respectively. The MF-infiltrated capillary enables bidirectional magnetic field sensing with maximum sensitivities of 46 pm/mT and -3 pm/mT, respectively. The PDMS-coated structure can realize the temperature measurement with a maximum sensitivity of 79.7 pm/°C. The current work possesses the advantage of bidirectionally magnetic tunability besides the temperature response, which is expected to be used in field such as vector magnetic fields and temperature dual-parameter sensing.

Optical fiber sensor for curvature and temperature simultaneous measurement based on an anti-resonance mechanism

Based on an anti-resonance mechanism, we propose and experimentally demonstrate an optical fiber sensor for simultaneous measurement of curvature and temperature. The sensor structure consists of a hollow fiber and a twisted graded index multimode fiber spliced between two single-mode fibers. By using the twisted graded index multimode fiber to change the energy distribution of the mode field, not only improve the coupling efficiency of the sensor but also the sensitivity of the curvature measurement. The experimental results show that the intensity of the resonance peak based on the anti-resonance mechanism decreases with the increase of curvature, while the resonance peak wavelength is insensitive to curvature. In addition, due to the thermal expansion and thermo-optic effect of the fiber, the wavelength of the resonance peak is red-shifted with increasing temperature, and the intensity of the resonance peak is insensitive to temperature. Therefore, the intensity and wavelength signals of the resonance peak are monitored separately, and the simultaneous measurement of displacement and temperature is realized. The maximum sensitivity of the proposed curvature sensor can reach −2.84 dB/m−1, the dynamic range of curvature is 0 m−1 to 20.18 m−1, and the temperature sensitivity of 20 pm/∘C is realized. The proposed sensor has a compact structure, simple preparation, high coupling efficiency, and good repeatability, making it an ideal choice for simultaneous measurement of curvature and temperature in structural monitoring, mechanical manufacturing, and other fields.

Simultaneous measurement of refractive index and temperature using a balloon-type optical fiber sensor

In the food industry, acetic acid is a compound often used as a preservative or additive, but it is also produced during the fermentation of various food products and constitutes a key marker of food safety and quality. Although accurate, sensitive, and selective, the traditional methods for determining acetic acid are also expensive and time-consuming. In this regard, optical fiber sensors have emerged as a possible alternative for the real-time monitoring of small molecules. In this work, we propose an optical fiber sensor for the simultaneous measurement of refractive index (RI) and temperature using a balloon-shaped structure with a single sensing element. The sensor, based on cladding modal interference, was characterized by its response to RI in the range from 1.320 to 1.352 RIU, using acetic acid solutions with concentrations between 0% and 50%(v/v), and by its response to temperature between 23 and 43 °C. A maximum sensitivity of 170.66 nm/RIU was obtained for RI, equivalent to 110.7 pm/%(v/v) in terms of concentration, and a maximum sensitivity of −119.2 pm/°C was obtained for temperature.

Multi-parameter terahertz metamaterial sensors based on single-layer quarter ring patterns

A terahertz metamaterial sensor based on a single-layer quarter ring pattern is proposed to realize the simultaneous measurement of temperature, refractive index, and other parameters through a metasurface consisting of a patterned quarter ring gold layer and a silicon substrate. Field finite element numerical simulations were performed to analyse the transmission and reflection spectra. A two-parameter sensor combined with electric field distribution was realized using multiple peaks, thus revealing the physical mechanisms of the interaction in metamaterial structures. In addition, the effect of each geometrical parameter on the sensor performance is also simultaneously analysed to verify the optimal selection of structural parameters. On this basis, the sensors are theoretically analysed at different incidence and polarization angles, and the results show that the transmittance is not sensitive to the polarization angle. The simulation results show that the transmittance at the resonant frequencies of 0.48 THz, 0.64 THz, 0.79 THz and 1.04 THz are 93.7 %, 79.1 %, 38.4 % and 50.8 %, respectively, and the refractive index sensitivities at the resonant frequencies are 6.84 GHz/RIU, 7.42 GHz/RIU, 8.22 GHz/RIU and 32.11 GHz/RIU, and quality factor Q of 6.76, 9.63, 15.51 and 26.28, respectively. The devices proposed in this study are simple in structure, easy to fabricate, easy to miniaturize and can be integrated for sensitivity, multi-parameter sensors. They can be functionally designed for chemical and biological sensing and other important applications.

The Doppler wind, temperature, and aerosol RMR lidar system at Kühlungsborn, Germany – Part 1: Technical specifications and capabilities

Abstract. This paper describes the technical specifications of the extensions made to the middle-atmospheric lidar facility at the Leibniz Institute of Atmospheric Physics in Kühlungsborn, Germany (54.12° N, 11.77° E). The upgrade complements the existing daylight-capable Rayleigh–Mie–Raman (RMR) temperature lidar with a nighttime-only RMR wind–temperature lidar. The new system comprises an independent lidar with laser, telescopes, and detectors, which is synchronized with and adapted to the (old) temperature lidar. As a result, with the combination of RMR lidars the atmosphere is probed with three (vertical and tilted) beams. This work intends to highlight the recent innovations in the construction of a Doppler–Rayleigh lidar system using the single-edge iodine-cell technique, which allows for the simultaneous measurement of wind, temperature, and aerosols. We will detail supporting subsystems that allow for a high degree of lidar automation and concisely provide key technical information about the system that will support readers in the development of additional RMR wind–temperature lidar systems. We show an example of time-resolved temperature and wind soundings reaching up to ∼ 90 km. These data agree well with ECMWF-IFS profiles between 35 and ∼ 50 km but show a much larger variability above. In the companion article, we will present the algorithm design and uncertainty budgets associated with the data processing chain.

Ultrasensitive RI and temperature sensor based on cascaded microfiber MZIs with Vernier effect

A sensitivity amplified optical fiber sensor based on Vernier effect by cascaded microfiber Mach-Zehnder interferometers (MZIs) is proposed and demonstrated for the simultaneous measurement of refractive index (RI) and temperature. The traditional single mode fiber is tapered into micrometer near the dispersion turning point to constitute MZI, and then cascaded to generate Vernier effect for the sensitivity enhancement. A novel phenomenon that the envelope of Vernier effect shifted in opposite directions decided by the free spectral ranges of the sensing and reference arms is clarified and demonstrated for the first time. Experimental results show that the RI sensitivity can be improved from 944 nm/RIU of single MZI to 18504 nm/RIU of Vernier effect, while the temperature sensitivity can be improved from −0.53 nm/℃ of single MZI to 9.49 nm/℃ of Vernier effect. Moreover, the proposed sensor with the merits of low hysteresis effect, good repeatability, high stability and good reliability, making it of great potential for biochemical trace detections without temperature-induced cross-sensitivity.

Dual-parameter combined measurement sensor based on tri-metal structure

Simultaneous measurement of strain and temperature in vibrating environments has always been a key technical issue in the field of structural health monitoring. To address the bottleneck of inadequate dual-parameter measurement performance in existing Fiber Bragg Grating (FBG) strain and temperature sensors, a new type of fiber optic grating sensor with anti-vibration capabilities for the measurement of both strain and temperature is proposed. The sensor utilizes a flexible hinge structure made of 304 steel with high elastic modulus for strain sensitization and a bimetallic structure composed of 7075 aluminum and 4 J36 Invar alloy for temperature sensitization, integrating both types of sensors. Theoretical analysis of the sensor was conducted, followed by the fabrication of a prototype and the establishment of a testing system for performance evaluation. The results show that the designed dual-parameter FBG sensor has a strain sensitivity of approximately 3.06 pm/µε, about 2.62 times that of a bare FBG, and a temperature sensitivity of about 50.2 pm/℃, roughly 4.97 times that of a bare FBG. In anti-vibration performance tests between 5–100 Hz, the wavelength drift of the strain and temperature sections of the FBG in the sensor were both within 1 pm, meeting the requirements for simultaneous measurement of strain and temperature in vibrating environments. These findings provide a reference for the development of similar sensors and further improvement of the measurement performance of FBG strain and temperature sensors.

Development of compact-modulated absorption/emission technique towards micro-gravity sooting flame measurements

To meet the experimental physical limitations on Chinese Space Station (CSS), three compact-modulated absorption/emission (CMAE) implementations are miniaturized progressively from original MAE layout, which are investigated as potential options for simultaneous soot temperature and volume fraction measurements in the axis-symmetric flames. Contrasted with the original MAE technique, a white LED point light source (diameter of ϕ = 8 mm) and a white LED planar light source (rectangle of 200 × 120 mm2) in turns replaces the laser source, by which the light beam homogeneous implementation is significantly simplified. Moreover, a 3-CMOS prism-based camera enables simultaneously recording flame two color radiations that reduces the detecting complexity. It is found that backlight beam intensity should be more than 2.5 times the flame radiation intensity to avoid abnormal extinction coefficient on the flame edge in this configuration. Moreover, the robustness and consistency of the three CMAEs measurements are validated with a standard Santoro’s flame, and low average standard deviation ranges of ±0.04∼±0.06 ppm and ±65.0∼± 96.3 K for soot volume fraction and temperature respectively is evaluated from error propagation assessment. As such, the proposed CMAE-2 and CMAE-3 layouts are promising candidates for high-fidelity flame soot parameters measurements under limited space, weight and power supply on CSS.

Dual D-shaped plastic optical fiber for simultaneous measurement of refractive index and temperature based on specklegram

The refractive index (RI) measurment of the liquid often changes with the sensor's temperature. Accurate RI measurements require simultaneous measurements of the liquid temperature to calibrate the RI measurement. This study proposed what we believe to be a novel dual D-shaped plastic optical fiber sensor capable of simultaneously measuring both RI and temperature. A fluorescent material made of rhodamine B (RhB) is embedded in one of the D-shaped structures of the dual D-shaped fiber, which can be excited by a green laser to produce orange fluorescence. The fluorescence and the input laser of the fiber are superimposed at the output end of the fiber to form a specklegram containing information of two wavelengths. It was found through experiments that the effects of temperature and RI change on the red and green channels of the specklegrams are different, and the neural network can learn this feature to complete the measurement of both RI and temperature parameters. For RI sensing, the maximum error between the average predicted value and the true value of the test set is 0.0005. For temperature sensing, the maximum error between the average predicted value and the true value of the test set is 0.26°C. In addition, because the intensity change of the fluorescence varies linearly with RI and temperature, the sensor also has good stability.

Customized-accuracy simultaneous sensing of temperature, pressure and acoustic impedance based on FBS in optical fiber

In this work, it is proposed a novel customized-accuracy simultaneous sensing of temperature, pressure and acoustic impedance based on forward Brillouin scattering (FBS) in optical fiber. By observing the variations in frequency shift-temperature, frequency shift-pressure and frequency shift-acoustic impedance for different radial acoustic modes in certain types of fibers, we propose a novel method for simultaneously measuring three parameters (temperature, pressure and acoustic impedance) using the changes of frequency shift of three FBS scattering peaks. It is very interesting that we can utilize numerous sensitivity combinations of three measured parameters corresponding to different frequency shifts in optical fibers, allowing for the selection of different combinations of measurement accuracy for temperature, pressure and acoustic impedance sensing, and thus meeting the different requirements for measurement accuracy in specific measurement applications. In a proof-of-concept experiment, a 1060-XP fiber is used as the sensing fiber. By choosing suitable sensitivity combinations of coefficients of frequency shift-temperature, frequency shift-pressure and frequency shift-acoustic impedance of the fiber, we achieve high-accuracy simultaneous measurement of temperature, pressure and acoustic impedance with low measurement uncertainties of 0.13 °C, 0.04 MPa and 0.006 MRayl, respectively. The proposed method not only realize temperature, pressure and acoustic impedance simultaneous sensing for the first time, but also open up a new way of fiber optic sensing with customized multi-parameter sensing accuracy.

All-sapphire fiber-optic sensor for the simultaneous measurement of ultra-high temperature and high pressure

An all-sapphire fiber-optic extrinsic Fabry-Perot interferometric (EFPI) sensor for the simultaneous measurement of ultra-high temperature and high pressure is proposed and experimentally demonstrated. The sensor is fabricated based on all-sapphire, including a sapphire fiber, a sapphire capillary and a sapphire wafer. A femtosecond (fs) laser is employed to drill a through hole at the side wall of the sapphire capillary to allow gas flow. The sapphire fiber is inserted from one side of the sapphire capillary. The sapphire wafer is fixed at the other side of the sapphire capillary. The first Fabry-Perot (FP) cavity, composed of the end face of the sapphire fiber and the front surface of the sapphire wafer, is used for measuring pressure, while the second FP cavity, composed of the two surfaces of the sapphire wafer, is used for measuring temperature. Experimental results show that the sensor can simultaneously measure ultra-high temperature and gas pressure within the temperature range of 20 - 1400 °C and the pressure range of 0 - 5 MPa. The temperature sensitivity is 0.0033 µm/°C, and the pressure sensitivity decreases as the temperature increases, reaching 1.8016 µm/MPa and 0.3253 µm/MPa at temperatures of 20 °C and 1400 °C, respectively.

A Dual-Mode Surface Acoustic Wave Delay Line for the Detection of Ice on 64°-Rotated Y-Cut Lithium Niobate.

Ice accumulation on infrastructure poses severe safety risks and economic losses, necessitating effective detection and monitoring solutions. This study introduces a novel approach employing surface acoustic wave (SAW) sensors, known for their small size, wireless operation, energy self-sufficiency, and retrofit capability. Utilizing a SAW dual-mode delay line device on a 64°-rotated Y-cut lithium niobate substrate, we demonstrate a solution for combined ice detection and temperature measurement. In addition to the shear-horizontal polarized leaky SAW, our findings reveal an electrically excitable Rayleigh-type wave in the X+90° direction on the same cut. Experimental results in a temperature chamber confirm capability for reliable differentiation between liquid water and ice loading and simultaneous temperature measurements. This research presents a promising advancement in addressing safety concerns and economic losses associated with ice accretion.

Erratum: Simultaneous measurements of nuclear-spin heat capacity, temperature, and relaxation in GaAs microstructures [Phys. Rev. B 105 , 155305 (2022)

Erratum: Simultaneous measurements of nuclear-spin heat capacity, temperature, and relaxation in GaAs microstructures [Phys. Rev. B <b>105</b> , 155305 (2022)

A WGM-FP hybrid microcavity for simultaneous measurement of NaCl concentration and temperature

Whispering gallery mode (WGM) resonator is sensitive to the external medium change due to its strong light-matter interaction. However, the temperature sensitivity of silica-based WGM resonators would cause crosstalk, which is a fatal shortcoming for those high-quality (Q) resonators. In this paper, a hybrid microcavity including WGM resonance and Fabry–Pérot (FP) interference is proposed for simultaneous measurement of NaCl concentration and temperature, using the same microcavity in the same system to obtain two types of optical signals. The experimental results indicate that the maximum measurement error of NaCl concentration and temperature without compensation is about ± 0.026 % and ± 1.1 °C, while they would be ± 0.012 % and ± 0.3 °C after compensation. Sharing one microcavity enables temperature compensation to achieve temperature synchronization, and sharing of one system ensures the simplicity and stability of the sensing platform.

Bimodal coaxial fiber sensor for simultaneous strain and temperature sensing for composite manufacturing process

Coaxial structured fibers have gained significant attention in sensor applications due to their design flexibility and ability for multifunctionality. However, the complex and thicker structure of a sensor can lead to stress concentration and signal interference when utilized for strain monitoring in composite manufacturing processes. To address this issue, we propose a bimodal coaxial fiber sensor capable of simultaneous temperature and strain measurement during composite cure and strain monitoring, while preserving the mechanical properties of the fabricated composites. To achieve bimodal sensing, we employ a multi-shell structure consisting of a multi-conductive layer with varying concentrations of multiwalled carbon nanotubes and a PEDOT:PSS layer, applied to a creep-enhanced ultra-high molecular weight polyethylene core fiber using a simple dip-coating method. The bimodal coaxial fiber sensor exhibits a high gauge factor (>4.1), stable cyclic tensile response (>1000 cycles), and linear response to stepwise temperature cycles. Moreover, the sensor demonstrates high sensing accuracy (<3% error) in cure strain monitoring and maintains the fracture toughness of the composite (<1% discrepancy) wherein it is embedded. These results confirm the significant potential of the bimodal coaxial fiber sensor for various applications in the composite industry and other fields.

Research on high sensitivity optical fiber sensing method for simultaneous measurement of seawater velocity and temperature

Aiming at the need of high sensitivity flow velocity and temperature sensor in ocean research, an optical fiber sensor for the simultaneous measurement of seawater velocity and temperature was proposed by coupling a reflective Panda fiber polarization interferometer with a hollow cylindrical cantilever, which combining the stress sensitivity of Panda fiber and optical vernier effect to achieve simultaneous measurement and sensitization of flow velocity and temperature. Firstly, the theoretical formulas of velocity sensitivity and temperature sensitivity were obtained by theoretical derivation and finite element simulation. Secondly, a velocity and temperature measurement system was established experimentally, and the maximum velocity sensitivity was –233.86 nm/(m/s) at 0.42 m/s with the mean relative error compared with the theoretical sensitivity was 3.8 %, the maximum temperature sensitivity was −14.5 nm/(°C) with the mean relative error compared with the theoretical sensitivity was 8 %. Finally, nine different sets of seawater velocity and temperature were measured using the sensitivity matrix and compared with the Acoustic Doppler Velocimetry and Conductivity-Temperature-Depth meter, the mean relative error of velocity and temperature measurement results were 2.8 % and 2 %, respectively. The optical fiber sensor based on the cantilever is expected to play an important role in the field of ocean flow field measurement because of high sensitivity and the ability to measure velocity and temperature simultaneously.

Novel Nanocomposites for Luminescent Thermometry with Two Different Modalities.

In this work, we successfully integrated fluorescent nanodiamonds (FNDs) and lanthanide ion-doped upconversion nanoparticles (UCNPs) in a nanocomposite structure for simultaneous optical temperature sensing. The effective integration of FND and UCNP shells was confirmed by employing high-resolution TEM imaging, X-ray diffraction, and dual-excitation optical spectroscopy. Furthermore, the synthesized ND@UCNP nanocomposites were tested by making simultaneous optical temperature measurements, and the detected temperatures showed excellent agreement within their sensitivity limit. The simultaneous measurement of temperature using two different modalities having different sensing physics but with the same composite nanoparticles inside is expected to greatly improve the confidence of nanoscale temperature measurements. This should resolve some of the controversy surrounding nanoscale temperature measurements in biological applications.