Thermal Resolution Research Articles

Multipath luminescent thermometry inCs3GdGe3O9:Yb3+, Er3+ phosphor

Nowadays, luminescent thermometry appeals the eyes of researchers more and more on account of the unique merits including non-invasive, fast response and relatively high sensitivity. However, most of reported up-conversion optical thermometric materials based on fluorescence intensity ratio (FIR) from thermal couple energy levels (TCELs) usually suffer from the overlap of two luminescence signals, leading to the deviation of the temperature readout. Herein, Cs3GdGe3O9:Yb3+,Er3+ phosphors were successfully synthesized. Multiple sharp peaks from green and red luminescence of Er3+ are observed. The emission signals even from the TCELs are well separated, enabling the accuracy of temperature detection to some extent. With the aid of the different thermo-responses of luminescence centered at 534, 559, 660 nm and their splitting peaks of Er3+, multi-mode optical thermometric techniques based on fluorescence decay time (4S3/2), FIR from TCELs, non-TCELs and their sub-energy levels in Cs3GdGe3O9:Yb3+,Er3+ upon single-beam light stimulation were designed. The resultant sample reveals excellent signal discernibility, eminent relative sensitivities, outstanding reversibility and glorious thermal resolution. Such results infer that Cs3GdGe3O9:Yb3+,Er3+ phosphors have the promising prospect in temperature monitoring fields.

Computation of conductive thermal distribution using non-homogenous graph theory for real-time applications in metal PBF process

The Powder Bed Fusion (PBF) process is inherently a thermal process with complex thermal interactions between different printed zones as well as different layers. There exist only a few methods such as finite element analysis (FEA), finite element differences (FDM), graph theory (GT), Goldak’s FEA, and Rosenthal equation, which are able to predict thermal temperature distribution throughout a printed layer (2D) or part (3D). All these approaches suffer from inherent limitations including the applied boundary conditions and computational time. A rapid and reliable method to compute thermal distribution throughout a printed part is pivotal to supporting real-time closed-loop monitoring and control, enabling thermal simulation software with rapid and precise prediction, and advancing current research on thermal-related abnormalities such as residual stress and distortion. The literature shows that the conventional graph theory is the fastest approach that generates relatively precise results in a fraction of the computational time of other techniques; however, the lack of a solution to the non-homogeneous governing thermal equation through GT has hampered this method in terms of thermal load resolution, accuracy in highly rapid process such as PBF, and scope of application. In this paper, we describe the characteristics that make GT a superior approach for real-time computation of thermal field compared to other similar approaches such as FDM. Also, we develop a solution to the non-homogeneous term of the thermal conduction equation by using GT. This solution represents a breakthrough for the development of precise real-time closed-loop monitoring and control systems by providing a precise numerical solution to the thermal conduction equation in a fraction of time compared with previous traditional methods such as FEA and FDM. Ongoing work includes the development of an intelligent monitoring and control system that leverages this solution in order to optimize scan strategy real-time in metal PBF.

Dataset of Wall-Resolved Large-Eddy Simulations Turbulent Pseudoboiling in Cryogenic Hydrogen Pipe Flows

In this paper, a dataset of wall-resolved large-eddy simulations of cryogenic hydrogen at supercritical pressure and different values of wall heat flux is presented. The aim is to provide a reference dataset for wall-function development under trans- and supercritical conditions, such as those found in liquid rocket engine applications. The employed numerical framework is a pressure-based segregated low-Mach-number approach based on an equation-of-state independent formulation. The wall-adapting local eddy-viscosity subgrid model is used for turbulence closure. Real-gas effects are taken from the National Institute for Standards and Technology database and stored as a function of a nondimensional temperature at the considered pressure. A validation and a grid-convergence analysis are first performed on an incompressible case without imposed heat flux. The effect of axial, radial, and azimuthal refinements on first- and second-order velocity statistics is discussed and compared with direct numerical simulation data from the literature. A parametric analysis at different wall heat fluxes is then performed by keeping the inlet mass flux, temperature, and Reynolds number constant. Particular attention is devoted to turbulent pseudoboiling and its effect on the wall temperature. The latter shows a more pronounced increment as the heat flux increases, which is attributed to the pseudochange of the phase in the core flow. Correspondingly, a flattening of the probability density function of the temperature is observed, and it is associated with the pseudoboiling interface forming close to the wall and causing a more intense stratification. First- and second-order statistics for velocity and selected scalars are then presented, and the effect of pseudoboiling is discussed. The effect of the wall heat flux on the viscous and thermal resolution of the computational grid is also assessed, and considerations on the relation between turbulent pseudoboiling and near-wall gradients is finally provided.

Yb3+, Er3+, Tm3+ co-doped β’Gd2(MoO4)3 for high sensitivity luminescence thermometry spanning from 300 to 890 K

Temperature sensing by using near-infrared (λ = 976 nm)-excited upconversion (UC) of Yb, Er and Tm co-doped orthorhombic β’Gd2(MoO4)3 combines remarkable good sensitivity and thermal resolution from room temperature to 890 K, thanks to the use of three different ratiometric luminescence probes. Two of them are based on pairs of thermally coupled levels, namely 2H11/2→4I15/2 vs 4S3/2→4I15/2 Er3+ green emissions (R1) and deep-red 3F3→3H6 vs NIR 3H4→3H6 Tm3+ emissions (R3). The third one uses non-thermally coupled levels, blue 1G4→3H6 vs deep-red 3F3→3H6 Tm3+ emissions (R2). This multiprobe approach allows the optimization of the thermometric parameters for each selected temperature range. Based on absolute thermal sensitivity (SABS), R1 is the best option for sensing from room temperature up to about 442 K, with R1 SABS = 103 × 10−4 K−1 and excellent thermal resolution δT< 0.04 K at 300 K, while at higher temperatures, R2 is the most adequate probe since it combines an extraordinary increase of R2 SABS up to 20300 × 10−4 K−1 at 776 K and very good δT< 0.2 K. When the relative thermal sensitivity (SREL) evaluation is required, R3 is the probe of choice from room temperature up to 522 K, offering simultaneously the highest R3 SREL = 3.3% K−1 and δT = 0.07 K at 300 K, with a minimum δT = 0.05 K achieved at 522 K, but R2 is still the most convenient probe for high temperature sensing, with R2 SREL = 1.6% K−1 and δT = 0.25 K. Therefore, doping β’Gd2(MoO4)3 simultaneously with Er3+ and Tm3+ provides a unique way to span the sensing temperature up to 890 K while maintaining suitable high thermal sensitivity and thermal resolution along the whole temperature range. Several favourable UC aspects specific of β’Gd2(MoO4)3 are identified as being responsible for advantages over its βNaYF4 counterpart for high temperature sensing.

Thermally stable upconverting Na3Zr2(SiO4)2PO4: Er3+/Yb3+ phosphors for displays and optical thermometry

The advanced new Er 3+ /Yb 3+ : Na 3 Zr 2 (SiO 4 ) 2 PO 4 (NASICON) monoclinic phosphors prepared by solid state reaction technique has been analyzed as upconverting materials. The crystal phase, structural parameters, surface morphology , different functional groups and bandgap of the synthesized phosphors have been analyzed. Under 980 nm continuous wave diode laser excitation, the codoping of Yb 3+ ions in the Er 3+ doped phosphors exhibit fascinating results. Stark sublevels observed in the upconversion emission have been used for the fluorescence intensity ratio (FIR) based thermometry. Relative & absolute sensitivity, thermal stability and temperature dependent CIE have been determined. The thermally stable Na 3 Zr 2 (SiO 4 ) 2 PO 4 : Er 3+ /Yb 3 phosphors with high color purity can be utilized in sensing, display and security purposes. Upon 980 nm excitation the UC emission obtained from Er 3+ /Yb 3+ doped Na 3 Zr 2 (SiO 4 ) 2 PO 4 phosphors have been utilized for temperature sensing and security ink application. • UC intensity enhancement of ~ 13 times has been observed with incorporation of Yb 3+ in Er 3+ doped Na 3 Zr 2 (SiO 4 ) 2 PO 4 upconverting phosphors. • Maximum absolute and relative sensitivity of the developed phosphor have been found to be 6.4 @ 393 K and 9.3 @ 303 K respectively with thermal resolution± 0.30 K at 303 K. • Thermal stability with activation energy ~ 0.30 eV has been studied upto 508 K.

Less is more: dimensionality reduction as a general strategy for more precise luminescence thermometry

Thermal resolution (also referred to as temperature uncertainty) establishes the minimum discernible temperature change sensed by luminescent thermometers and is a key figure of merit to rank them. Much has been done to minimize its value via probe optimization and correction of readout artifacts, but little effort was put into a better exploitation of calibration datasets. In this context, this work aims at providing a new perspective on the definition of luminescence-based thermometric parameters using dimensionality reduction techniques that emerged in the last years. The application of linear (Principal Component Analysis) and non-linear (t-distributed Stochastic Neighbor Embedding) transformations to the calibration datasets obtained from rare-earth nanoparticles and semiconductor nanocrystals resulted in an improvement in thermal resolution compared to the more classical intensity-based and ratiometric approaches. This, in turn, enabled precise monitoring of temperature changes smaller than 0.1 °C. The methods here presented allow choosing superior thermometric parameters compared to the more classical ones, pushing the performance of luminescent thermometers close to the experimentally achievable limits.

Invisible Thermoplasmonic Indium Tin Oxide Nanoparticle Ink for Anti-counterfeiting Applications.

In this study, we present a thermoplasmonic transparent ink based on a colloidal dispersion of indium tin oxide (ITO) nanoparticles, which can offer several advantages as anti-counterfeiting technology. The custom ink could be directly printed on several substrates, and it is transparent under visible light but is able to generate heat by absorption of NIR radiation. Dynamic temperature mapping of the printed motifs was performed by using a thermal camera while irradiating the samples with an IR lamp. The printed samples presented fine features (in the order of 75 μm) and high thermal resolution (of about 250 μm). The findings are supported by thermal finite-element simulations, which also allow us to explore the effect of different substrate characteristics on the thermal readout. Finally, we built a demonstrator comprising a QR Code invisible to the naked eye, which became visible in thermal images under NIR radiation. The high transparency of the printed ink and the high speed of the thermal reading (figures appear/disappear in less than 1 s) offer an extremely promising strategy toward low-cost, scalable production of photothermally active invisible labels.

Characterizing the external exposome using passive samplers-comparative assessment of chemical exposures using different wearable form factors.

Organic contaminants are released into the air from building materials/furnishings, personal care, and household products. Wearable passive samplers have emerged as tools to characterize personal chemical exposures. The optimal placementof these samplers on an individual to best capture airborne exposures has yet to be evaluated. To compare personal exposure to airborne contaminants detected using wearable passive air samplers placed at different positions on the body. Participants (n = 32) simultaneously wore four passive Fresh Air samplers, on their head, chest, wrist, and foot for 24 hours. Exposure to 56 airborne organic contaminants was evaluated using thermal desorption gas chromatography high resolution mass spectrometry with a targeted data analysis approach. Distinct exposure patterns were detected by samplers positioned on different parts of the body. Chest and wrist samplers were the most similar with correlations identified for 20% of chemical exposures (Spearman's Rho > 0.8, p < 0.05). In contrast, the greatest differences were found for head and foot samplers with the weakest correlations across evaluated exposures (8% compounds, Spearman's Rho > 0.8, p < 0.05). The placement of wearable passive air samplers influences the exposures captured and should be considered in future exposure and epidemiological studies. Traditional approaches for assessing personal exposure to airborne contaminants with active samplers presents challenges due to their cost, size, and weight. Wearable passive samplers have recently emerged as a non-invasive, lower cost tool for measuring environmental exposures. While these samplers can be worn on different parts of the body, their position can influence the type of exposure that is captured. This study comprehensively evaluates the exposure to airborne chemical contaminants measured at different passive sampler positions worn on the head, chest, wrist, and foot. Findings provide guidance on sampler placement based on chemicals and emissionsources of interest.

ERRORS IN THERMAL IMAGERS TEMPERATURE RESOLUTION DETERMINING

Thermal imaging methods of environmental observation are often accompanied by the need to quantify the temperature distribution on the object’s surfaces. In such cases, the accuracy of modeling the information conversion processes that occur in thermal imaging systems is essential. All questions concerning the determination of thermal imagers temperature resolution are important. Experimental methods for determining temperature resolution in this sense are quite unambiguous and well-established in practice. And calculation methods are still being refined and are of interest to the scientific community.&#x0D; The article is devoted to the development of practical methods for calculating the thermal imagers temperature resolution. Such methods must be on the hand one accurate enough, and on the other hand - simple enough to be used in design organizations. The definition of the calculations error is also considered. The calculation model is based on the concept of equivalent noise temperature difference NETD as the most general characteristic of energy transformations in thermal imaging observations. The definition of NETD is based on the use of the thermal imager signal transmission function. A simplified version of the calculation method and an example of determining the temperature resolution for a thermal imager with a microbolometric matrix detector are presented. Such thermal imagers currently occupy a significant part of the market and the calculation of the characteristics of the device with a standard specification may be of interest to specialists. The influence of some elements of the mathematical information transformations model on the temperature resolution is shown. For example, as the background temperature increases, the temperature resolution decreases. The analysis of the proposed calculation model allowed us to outline ways to improve (reduce) temperature resolution. A feature of the developed methods is the possibility of their use for different thermal imaging systems, for example, for polarizing thermal imagers.&#x0D;

Excitation power density dependence of a primary luminescent thermometer based on Er3+, Yb3+: GdVO4 microcrystals operating in the visible

A discussion about the calibration of the Er3+,Yb3+:GdVO4 microcrystals as a luminescent primary thermometer based on the known equation of state of Boltzmann distribution of the electronic population of the two Erbium emitting coupled levels has been given. Its validity has been demonstrated. Besides, when Er3+,Yb3+:GdVO4 microcrystals acting as secondary thermometer, it has been proven the dependence of the thermometric ratio based on the integrated intensities of the green visible emissions arising from the two thermally coupled levels of erbium, 2H11/2 and 4S3/2, on the excitation power density for the Er3+,Yb3+:GdVO4 microcrystals. The effect of the excitation power density on the relative thermal sensitivity and temperature resolution has been also analyzed.

Modulating the thermally coupled status of energy levels in rare earth ions for sensitive optical temperature sensing

Luminescence thermometry technique, which utilizes the rare earth ions activated luminescent nanomaterials as sensing media, has presented great potential in various fields owing to its high spatial, temporal, and thermal resolutions. Nevertheless, the development of sensitive luminescent nanothermometers working in the biological window remains a challenge. Here, Tm3+-Yb3+ codoped NaYF4 nanocrystals, the excitation and emission wavelengths of which are both located within the near-infrared region, are investigated for optical temperature measurement via the fluorescence intensity ratio (FIR) approach. The thermal population and decay rates involved in the thermally coupled levels (3F2, 3 and 3H4) are verified to play an important role in regulating the thermal coupling status. The measurement sensitivity of as-prepared nanothermometers is optimized through modulating the Tm3+ surrounding environment and a maximum sensitivity of about 2.13% K−1 is achieved in the physiological temperature range. Besides, a parameter named as thermally coupled degree is defined in this work to quantify the coupling between the thermally coupled levels. According to the conclusion of our work, special attention has to be taken for rationally constructing FIR-based optical temperature sensors.

Infrared Thermography for Monitoring of Freeze Drying Processes-Part 2: Monitoring of Temperature on the Surface and Vertically in Cuvettes during Freeze Drying of a Pharmaceutical Formulation.

The coupling of an infrared (IR) camera to a freeze dryer for monitoring of the temperature of a pharmaceutical formulation (sucrose/mannitol solution, 4:1%, m/m) during freeze-drying has been exploited further. The new development allows monitoring of temperatures simultaneously at the surface as well as vertically, (e.g., in depth) along the side using custom-made cuvettes. The IR camera was placed on the chamber roof of a process-scale freeze dryer. Monitoring of cuvettes containing the formulation took place from above where one side of each cuvette was equipped with a germanium window. The Ge-window was placed next to an IR mirror having a 45° angle. The long-wave infrared radiation (LWIR) coming from the inside of the cuvette was reflected upwards toward the IR camera. Accurate recording of the temperature along the cuvettes’ depth profile was therefore possible. Direct imaging from −40 °C to 30 °C took place every 60 s on the surface and on the side with a 2 × 2 mm resolution per IR pixel for 45 h resulting in 2700 thermograms. Results are presented for freeze-drying of a pharmaceutical formulation as a function of time and spatially for the entire side (depth) of the cuvette. As the sublimation process was progressing, the spatial resolution (84 IR pixels for the side-view and 64 pixels for the surface-view) was more than sufficient to reveal lower temperatures deeper down in the material. The results show that the pharmaceutical formulation (a true solution at the onset) dries irregularly and that the sublimation front does not progress evenly through the material. During secondary drying, potential evaporative cooling of upper layers could be detected thanks to the high thermal and spatial resolution.

Analytical characterization of erucamide degradants by mass spectrometry

Polyolefins use erucamide as one of their primary slip agents. The degradation of erucamide can occur during polymer processing and long-term storage, leading to the formation of numerous oxidation products. Erucamide degradation produces compounds that adversely affect the odor and color properties of polyolefins. The article describes the comprehensive characterization of erucamide degradation products formed in three different lots of low-density polyethylene (LDPE) using thermal desorption-gas chromatography mass spectrometry (TD-GC/MS) and liquid chromatography-high resolution mass spectrometry (LCHRMS) techniques. More than 20 volatile and non-volatile degradation compounds of erucamide were identified in LDPE. The structures of non-volatile degradants were predicted using both the molecular formula generated and MS/MS fragmentation data obtained by LCHRMS. The non-volatile and volatile degradation compounds formed in odorous LDPE resins were compared with that of the reference sample of LDPE having no odor. Further, the plausible mechanism of formation of volatile and non-volatile degradation compounds of erucamide is proposed.

Reaction Mechanisms Testing with Spatial and Thermal Resolutions of Methane/Air Flames

Spatial and thermal dispersals of hydroxyl (OH), formaldehyde (CH2O), and other minor species have been acquired using various detail reaction mechanisms in the weak flame of stoichiometric methane and air mixture at ambient pressure. The weak flame was simulated inside a microflowcombustor with a prescribed temperature profile which releases a very small amount of heat. A wide reaction zone (~ 1 cm) was observed for methane and air flames compared to normal/conventional flames. Detailed oxidation analysis was carried out based on the normal and weak flames simulations. The computational flame structure was assessed with the experimentalresults available in the existing literature. Numerical modeling under the experimental conditions with various detail mechanism predicts a similar wide reaction zone. However, the species production and consumption temperatures were observed to vary for the different mechanisms used in present studies. The GRI mech 3.0 shows a typical two-peak heat release rate profile. The initial breakdown of fuel is vital for such scatter. The production of OH radical governs the initial breakdown of fuel at the intermediate temperatures. The present investigation is pretty useful in understanding the chemistry of intermediate species for different fuel-air mixtures specially at intermediate temperatures 800–1200 K.

Investigation of CLYC-6 for thermal neutron detection and CLYC-7 for fast neutron spectrometry

Highly enriched 6Li and 7Li Cs2LiYCl 6 (CLYC) scintillators were investigated in view of their application as thermal neutron counter (CLYC-6) and as fast neutron spectrometer (CLYC-7) in the recently developed B-RAD radiation survey metre, an instrument designed to work in regions of high magnetic fields, currently equipped with a probe for photon dose rate measurements and γ-spectrometry. Both crystals were irradiated with a 2.5 MeV mono-energetic neutron beam from a Deuterium–Deuterium (D–D) generator and characterised in terms of neutron/γ-ray (n/γ) discrimination capability by the Pulse Shape Discrimination (PSD) method, energy resolution and quenching factor. Both crystals exhibit an excellent n/γ discrimination, quantified by a Figure of Merit higher than 2. The measured thermal energy resolution of CLYC-6 is 6%. The quenching factor for the 6Li(n,t)α thermal neutron reaction is 0.65 and for the 35Cl(n,p)35S reaction is 0.91. The measured neutron detection efficiency per unit volume of CLYC-6 is 60% higher than that of a 3He proportional counter. CLYC-7 was tested as a fast neutron spectrometer below 10 MeV, when irradiated with continuum neutron spectra from Am–Be and 252Cf sources. A proton/α-particle (p/α) discrimination was performed exploiting the PSD technique, without any unfolding procedure. The resulting spectra match the corresponding ISO spectra better than the spectra without the p/α discrimination, especially in the range 3 MeV to 5 MeV. A more sensitive PSD algorithm might help to improve particle discrimination at lower energies, while different reaction channels arise at higher energies preventing a spectrometry analysis.

Spatiotemporal Evolution of Temperature During Transient Heating of Nanoparticle Arrays.

Nanoparticles (NPs) are promising agents to absorb external energy and generate heat. Clusters of NPs or NP array heating have found an essential role in several biomedical applications, diagnostic techniques, and chemical catalysis. Various studies have shed light on the heat transfer of nanostructures and greatly advanced our understanding of NP array heating. However, there is a lack of analytical tools and dimensionless parameters to describe the transient heating of NP arrays. Here we demonstrate a comprehensive analysis of the transient NP array heating. Firstly, we develop a set of analytical solutions for the NP array heating and provide a useful mathematical description of the spatial-temporal evolution of temperature for 2D, 3D, and spherical NP array heating. Based on this, we introduce the concept of thermal resolution that quantifies the relationship between minimal heating time, NP array size, energy intensity, and target temperature. Lastly, we define a set of dimensionless parameters that characterize the transition from confined heating to delocalized heating. This study advances the understanding of nanomaterials heating and guides the rational design of innovative approaches for NP array heating.

Reliable and Remote Monitoring of Absolute Temperature during Liver Inflammation via Luminescence-Lifetime-Based Nanothermometry.

Temperature of tissues and organs is one of the first parameters affected by physiological and pathological processes, such as metabolic activity, acute trauma, or infection-induced inflammation. Therefore, the onset and development of these processes can be detected by monitoring deviations from basal temperature. To accomplish this, minimally invasive, reliable, and accurate measurement of the absolute temperature of internal organs is required. Luminescence nanothermometry is the ideal technology for meeting these requirements. Although this technique has lately undergone remarkable developments, its reliability is being questioned due to spectral distortions caused by biological tissues. In this work, how the use of bright Ag2 S nanoparticles featuring temperature-dependent fluorescence lifetime enables reliable and accurate measurement of the absolute temperature of the liver in mice subjected to lipopolysaccharide-induced inflammation is demonstrated. Beyond the remarkable thermal sensitivity (≈ 3% °C-1 around 37 °C) and thermal resolution obtained (smaller than 0.3 °C), the results included in this work set a blueprint for the development of new diagnostic procedures based on the use of intracorporeal temperature as a physiological indicator.

Physics-based modelling and validation of inter-granular helium behaviour in SCIANTIX

In this work, we propose a new mechanistic model for the treatment of helium behaviour at the grain boundaries in oxide nuclear fuel. The model provides a rate-theory description of helium inter-granular behaviour, considering diffusion towards grain edges, trapping in lenticular bubbles, and thermal re-solution. It is paired with a rate-theory description of helium intra-granular behaviour that includes diffusion towards grain boundaries, trapping in spherical bubbles, and thermal re-solution. The proposed model has been implemented in the meso-scale software designed for coupling with fuel performance codes SCIANTIX. It is validated against thermal desorption experiments performed on doped UO2 samples annealed at different temperatures. The overall agreement of the new model with the experimental data is improved, both in terms of integral helium release and of the helium release rate. By considering the contribution of helium at the grain boundaries in the new model, it is possible to represent the kinetics of helium release rate at high temperature. Given the uncertainties involved in the initial conditions for the inter-granular part of the model and the uncertainties associated to some model parameters for which limited lower-length scale information is available, such as the helium diffusivity at the grain boundaries, the results are complemented by a dedicated uncertainty analysis. This assessment demonstrates that the initial conditions, chosen in a reasonable range, have limited impact on the results, and confirms that it is possible to achieve satisfying results using sound values for the uncertain physical parameters.

Using near–surface temperature data to vicariously calibrate high-resolution thermal infrared imagery and estimate physical surface properties

Thermal response of the surface to solar insolation is a function of the topography and the thermal physical characteristics of the landscape, which include bulk density, heat capacity, thermal conductivity and surface albedo and emissivity. Thermal imaging is routinely used to constrain thermal physical properties by characterizing or modeling changes in the diurnal temperature profiles. Images need to be acquired throughout the diurnal cycle – typically this is done twice during a diurnal cycle, but we suggest multiple times. Comparison of images acquired over 24 hours requires that either the data be calibrated to surface temperature, or the response of the thermal camera is linear and stable over the image acquisition period. Depending on the type and age of the thermal instrument, imagery may be self-calibrated in radiance, corrected for atmospheric effects, and pixels converted to surface temperature. We used an experimental instrumentation where the calibration should be stable, but calibration coefficients are unknown. Cases may occur where one wishes to validate the camera's calibration. We present a method to validate and calibrate the instrument and characterize the thermal physical properties for areas of interest. Finally, in situ high-temporal-resolution oblique thermal imaging can be invaluable in preparation for conducting overflight missions. We present the following:•The use of oblique thermal high temporal resolution thermal imaging over diurnal or multiday periods for the characterization of landscapes has not been widespread but poses great potential.•A method of collecting and analyzing thermal data that can be used to either determine or validate thermal camera calibration coefficients.•An approach to characterize thermophysical properties of the landscape using oblique temporally high-resolution thermal imaging, combined with in situ ground measurements.

Low-doped LaVO4:Eu3+ phosphor for multimode optical thermal sensing.

In the last decade much attention has been paid to the development of novel approaches in luminescence thermometry, which could allow contactless and noninvasive temperature sensing when traditional thermometers are useless. Typically, an optical thermometer exploits a distinct luminescence parameter to define temperature. However, the use of multimode sensors can significantly broaden the working range and improve the reliability of the temperature measurements. In this work, a Eu3+-doped LaVO4 sample was successfully utilized as a thermal sensor within a wide temperature range of 98-723 K based on monitoring various temperature-sensitive luminescence features. Different thermal sensing strategies were assessed and compared in terms of thermal sensitivity and temperature resolution. The best thermometric performances of the Eu3+-doped LaVO4 sensor reached an Sr = 1.49% K-1 and a ΔT = 0.6 K at room temperature. All the studies performed showed that the LaVO4:Eu3+ phosphor is a prospective multimode optical thermometer.