Thermal Imaging Applications Research Articles

Infrared transmission and refractive index dispersion of mixed-chalcogen Ge-Sb-S-Se glasses for use in molded lens applications

In an effort to augment thermal and mechanical properties of ternary Ge-Sb-Se glass for use in molded lens applications, mixed-chalcogen Ge27.5Sb12.5SxSe60-x glasses have been investigated in this study with a particular attention paid to refractive index dispersion as well as infrared transmission edge. Changes in Vickers hardness, glass transition temperature, dilatometric softening temperature and thermal expansion coefficient are elucidated in terms of structural evolutions that sulfur induces. Infrared transmission edge blueshifts upon the addition of sulfur, which can be nicely interpreted in connection with average bond energy and molar mass of a given composition based on a postulation that this glass behaves as a single average harmonic oscillator in shaping multiphonon absorption. Refractive index at the long-wavelength infrared range becomes more dispersive with increasing sulfur content in these sulfur-selenide glasses, and thereby their dispersion can be pinpointed via adjusting S content. The Abbe diagram in the long-wavelength infrared region is extended towards the high-dispersion side, thus enhancing practicality of the chalcogenide glasses as in the form of lens and/or filter for the thermal imaging applications.

Investigation on Rashba spin–orbit interactions in two dimension quantum array for thermal imaging applications

In this work, we investigated the optical properties of a two dimensional quantum array using tight binding method in the presence of the Rashba spin–orbit (RSOI) interaction. The results show that ribbon array has sharp peaks with maximum absorption up to 70 (arb. units), at the energy of 95 meV with FHWM of 48 meV that can be used in thermal imaging applications. We have studied the effect of structural parameters like the shape of the array (square or ribbon), number of array sites, number of potential valleys and material on the absorption spectrum. The results show that with migrating from a square shape to ribbon, sharp peaks convert to smaller and larger peaks. Also, the effect of applied external parameters like electric and magnetic fields have been studied. For electrical field, absorption spectrum has symmetry with respect to the applied electrical axis Maximum absorption can be achieved when the electric field applied along vertical aside of the array. But, this symmetry has broken by means of the RSOI interaction and there is a critical angle, where absorption coefficient has maximum value. Also, there is a red and blue shift with applying an electrical and magnetic field that can be used for tuning absorption in the desired wavelength. These facts can help experimentalist to design their desired thermal detector.

Black phosphorus-based van der Waals heterostructures for mid-infrared light-emission applications

Mid-infrared (MIR) light-emitting devices play a key role in optical communications, thermal imaging, and material analysis applications. Two-dimensional (2D) materials offer a promising direction for next-generation MIR devices owing to their exotic optical properties, as well as the ultimate thickness limit. More importantly, van der Waals heterostructures—combining the best of various 2D materials at an artificial atomic level—provide many new possibilities for constructing MIR light-emitting devices of large tuneability and high integration. Here, we introduce a simple but novel van der Waals heterostructure for MIR light-emission applications built from thin-film BP and transition metal dichalcogenides (TMDCs), in which BP acts as an MIR light-emission layer. For BP–WSe2 heterostructures, an enhancement of ~200% in the photoluminescence intensities in the MIR region is observed, demonstrating highly efficient energy transfer in this heterostructure with type-I band alignment. For BP–MoS2 heterostructures, a room temperature MIR light-emitting diode (LED) is enabled through the formation of a vertical PN heterojunction at the interface. Our work reveals that the BP–TMDC heterostructure with efficient light emission in the MIR range, either optically or electrically activated, provides a promising platform for infrared light property studies and applications.

Application of thermal imaging for plant disease detection

The effects of plant diseases on agricultural production worldwide contribute to significant economic and post-harvest losses. To maintain the sustainability of the farming sector, the early detection of plant and pathogens is essential. Non - destructive methods for tracking the health conditions of plants in real-time applications are among the most realistic and feasible in this regard. Owing to non - destructive methods and non - contact measuring devices, thermal imaging advancement has become an essential technique in all fields. Thermal imaging operates by emitting infrared irradiation in all materials. The method, therefore, uses radiation to create an image of the thermal distribution of the body surface. This approach is useful for all areas where the difference in temperature helps in the area/object analyses. Therefore, this paper briefly explores the potential for thermal imaging to be used to detect plant disease in the control area and the field.

The applications of infrared thermography in surgical removal of retained teeth effects assessment

At the beginning, applications of thermal imaging in dentistry were focused mostly on the assessment of thermal effects during filling cavities, laser treatment and inflammation of periodontal tissues. The biggest problem in thermal imaging was limiting access and rapid change of humidity when the mouth opens during measurements. However, nowadays thermal map of body surface is correlated with inflammatory state changing inner mouth. The aim of this study was to assess the suitability of thermal imaging to localize the inflammation and monitor treatment effects after surgical removal of third retained molar teeth. The cohort consisted of 27 patients with referral for the surgical extraction of the third retained molar. Thermal imaging of the sagittal face was performed before and after the procedure and on the first, fourth and seventh day after the extraction. Obtained thermal maps are correlated with the third molar teeth inflammation location. Moreover, the changes of temperature in the area of both the tooth and the cheek correspond to the mechanisms of wound healing described in the literature. Obtained results were not only qualitative but also quantitative what was confirmed by statistically significant difference. It seems that thermal imaging, which is a noninvasive method, can be used to monitor treatment processes after surgical procedures, as well as on the location of inflammation.

On the Local Constitutive Behavior of Friction Stir Welded AISI 304 Stainless Steel Joints

The uniaxial tensile test is often used to determine the mechanical properties of a material like its yield strength and elastic limit. However, some of the recent advances in imaging Non Destructive Evaluation (NDE) modalities offer experimental tools which, apart from determining the conventional properties, also make it possible to visualise and map the dynamic strain evolution during monotonic loading and correlate it with the micro mechanisms of deformation. Infrared thermal imaging (IRT) and digital image correlation (DIC) are two such advanced NDE methods which are being widely used in experimental mechanics. Infrared thermal imaging maps the thermal gradient including the dynamic thermal transients that may occur during the tensile testing and is based on the detection of infrared radiation. Digital image correlation, a non-contact optical method based on grey value correlation before and after deformation, maps the magnitude of deformation on the surface of the object under load. In this investigation, the global and local properties of a friction stir welded joint of 304 Austenitic Stainless steel through the simultaneous application of thermal imaging and digital image correlation. By characterising the various stages of tensile deformation, this study enabled correlation of the thermal and strain evolutions and to provide deeper insights into the micro-mechanisms of the associated deformation phenomenon.

Using Thermal Imaging to Monitor Body Temperature of Koalas (Phascolarctos cinereus) in A Zoo Setting.

Simple SummaryBody temperature regulation is integral for the health and well-being of animals, especially in Zoo settings. Endothermic vertebrates such as small mammals are able to maintain a constant internal body temperature; however, extreme variation in body temperature may be reflective of underlying injuries or health issues. Thus, new technology that can enable the measurement of body temperature of small mammals without need for capture and handling can be very useful for the monitoring of animals in Zoos. In this study, we report the application of an IR thermal imaging camera for monitoring the body temperature of koalas. We found that the eye and abdomen were the most consistent body features to record body temperature. This tool will have useful application for welfare evaluation of small mammals, such as koalas in Zoos.Non-invasive techniques can be applied for monitoring the physiology and behaviour of wildlife in Zoos to improve management and welfare. Thermal imaging technology has been used as a non-invasive technique to measure the body temperature of various domesticated and wildlife species. In this study, we evaluated the application of thermal imaging to measure the body temperature of koalas (Phascolarctos cinereus) in a Zoo environment. The aim of the study was to determine the body feature most suitable for recording a koala’s body temperature (using coefficient of variation scores). We used a FLIR530TM IR thermal imaging camera to take images of each individual koala across three days in autumn 2018 at the Wildlife Sydney Zoo, Australia. Our results demonstrated that koalas had more than one reliable body feature for recording body temperature using the thermal imaging tool—the most reliable features were eyes and abdomen. This study provides first reported application of thermal imaging on an Australian native species in a Zoo and demonstrates its potential applicability as a humane/non-invasive technique for assessing the body temperature as an index of stress.

Thermo-Chromic Response of Polymer Stabilized Cholesteric Liquid Crystal for Thermal Imaging

Cholesteric liquid crystal (Ch-LC) exhibits many remarkable optical properties due to formation of a macroscopic helical structure. A low amount of monomer (5wt.%) is dispersed into cholesteric liquid crystal and get polymerized under UV radiations to form polymer stabilized cholesteric texture (PSCT). The thermo-chromic response made this device suitable for the developing applications in thermal imaging. Temperature based measurements of PSCT exploits the key property of some polymer stabilized cholesteric liquid crystals (PSCLC) to reflect definite colors at specific temperatures. The selective color of PSCT texture shifts with raise in temperature from 30oC to 85oC, which can be utilized in thermal imaging applications.

Evaluating Remotely-Sensed Grapevine (Vitis vinifera L.) Water Stress Responses Across a Viticultural Region

The evolving spatial and temporal knowledge about vineyard performance through the use of remote sensing offers new perspectives for vine water status studies. This paper describes the application of aerial thermal imaging to evaluate vine water status to improve irrigation scheduling decisions, water use efficiency, and overall winegrape quality in the Coonawarra viticultural region of South Australia. Airborne infrared images were acquired during the 2016 and 2017 growing seasons in the region of Coonawarra, South Australia. Several thermal indices of crop water status (CWSI, Ig, (Tc-Ta)) were calculated that correlated with conventional soil and vine water status measures (Ψpd, Ψs, gs). CWSI and Ig could discriminate between the two cultivars used in this study, Cabernet Sauvignon (CAS) and Shiraz (SHI), as did the conventional water stress measures. The relationship between conventional vine water status measures appeared stronger with CWSI in the warmer and drier season (2016) compared to the cooler and wetter season (2017), where Ig and (Tc-Ta) showed stronger correlations. The study identified CWSI, Ig and (Tc-Ta) to be reliable indicators of vine water status under a variety of environmental conditions. This is the first study to report on high resolution vine water status at a regional scale in Australia using a combination of remote and direct sensing methods. This methodology is promising for aerial surveillance of vine water status across multiple blocks and cultivars to inform irrigation scheduling.

Thermal imaging applications in neonatal care: a scoping review

BackgroundIn neonatal care, assessment of the temperature of the neonate is essential to confirm on-going health, and as an early signal of potential pathology. However, some methods of temperature assessment involve disturbing the baby, disrupting essential sleep patterns, and interrupting maternal/infant interaction. Thermal imaging is a completely non-invasive and non-contact method of assessing emitted temperature, but it is not a standard method for neonatal thermal monitoring. To examine the potential utility of using thermal imaging in neonatal care, we conducted a comprehensive systematic scoping review of thermal imaging applications in this context.MethodsWe searched EMBASE, MEDLINE and MIDIRS.ResultsFrom 442 hits, 21 met the inclusion criteria and were included in the review. A significant number (n = 9) were published in the last 8 years. All the studies were observational studies, with 20 out of 21 undertaken in North America or Europe. Most of them had small cohorts (range 4–29 participants). The findings were analysed narratively, to establish the issues identified in the included studies. Five broad themes emerged for future examination. These were: general thermal physiology; heat loss and respiratory monitoring; identification of internal pathologies, including necrotising enterocolitis; other uses of thermal imaging; and technical concerns. The findings suggest that thermal imaging is a reliable and non-invasive method for continuous monitoring of the emitted temperature of the neonates, with potential for contributing to the assurance of wellbeing, and to the diagnosis of pathologies, including internal abnormalities. However, the introduction of thermal imaging into everyday neonatology practice has several methodological challenges, including environmental parameters, especially when infants are placed in incubators or open radiant warmers.ConclusionIn conclusion, although the first attempt at using thermal imaging in neonatal care started in the early-1970s, with promising results, and subsequent small cohort studies have recently reinforced this potential, there have not been any large prospective studies in this area that examine both the benefits and the barriers to its use in practice.

Shape memory polymer resonators as highly sensitive uncooled infrared detectors

Uncooled infrared detectors have enabled the rapid growth of thermal imaging applications. These detectors are predominantly bolometers, reading out a pixel’s temperature change due to infrared radiation as a resistance change. Another uncooled sensing method is to transduce the infrared radiation into the frequency shift of a mechanical resonator. We present here highly sensitive resonant infrared sensors, based on thermo-responsive shape memory polymers. By exploiting the phase-change polymer as transduction mechanism, our approach provides 2 orders of magnitude improvement of the temperature coefficient of frequency. Noise equivalent temperature difference of 22 mK in vacuum and 112 mK in air are obtained using f/2 optics. The noise equivalent temperature difference is further improved to 6 mK in vacuum by using high-Q silicon nitride membranes as substrates for the shape memory polymers. This high performance in air eliminates the need for vacuum packaging, paving a path towards flexible non-hermetically sealed infrared sensors.

Characterization of Temperature Rise in Alternating Current Electrothermal Flow Using Thermoreflectance Method.

Alternating current electrothermal flow (ACET) induced by Joule heating is utilized to transport biologically relevant liquids in microchannels using simple electrode designs. However, Joule heating may cause significant temperature rises, which can degrade biological species, and hence, ACET may become impractical for biomicrofluidic sensors and other possible applications. In this study, the temperature rise at the electrode/electrolyte interface during ACET flow is measured using a high-resolution, noninvasive, thermoreflectance imaging method, which is generally utilized in microelectronics thermal imaging applications. The experimental findings reveal that Joule heating could result in an excessive temperature rise, exceeding 50 °C at higher voltage levels (20 Vpp). The measured data are compared with the results of the enhanced ACET theoretical model, which predicts the temperature rise accurately, even at high levels of applied voltages. Overall, our study provides a temperature measurement technique that is used for the first time for electrode/electrolyte systems. The reported results are critical in designing biomicrofluidic systems with significant energy dissipation in conductive fluids.

Application of Ultrasound Thermal Imaging for Monitoring Laser Ablation in Ex Vivo Cardiac Tissue.

Laser ablation can be used to treat atrial fibrillation by thermally isolating pulmonary veins. In this study, we evaluated the feasibility of high-resolution (<1 mm) ultrasound thermal imaging to monitor spatial temperature distribution during laser ablation on ex vivo cardiac tissue. Laser ablation (808 nm) was performed on five porcine cardiac tissue samples. A thermocouple was used to measure the interstitial tissue temperature during the laser ablation process. Tissue-strain-based ultrasound thermal imaging was conducted to monitor the spatial distribution of the temperature in the cardiac tissue. The tissue temperature was estimated from the time shifts of ultrasound signals owing to the changes in the speed of sound and was compared with the measured temperature. The temperature estimation coefficient k of porcine cardiac tissue was calculated from the estimated thermal strain and the measured temperature. The degree of tissue coagulation (temperatures > 50°C) was derived from the estimated temperature and was compared with that of the tested cardiac tissue. The estimated tissue temperature using strain-based ultrasound thermal imaging at a depth of 1 mm agreed with thermocouple measurements. During the 30-second period of the laser ablation process, the estimated tissue temperature increased from 25 to 70°C at a depth of 0.1 mm, while the estimated temperature at a depth of 1 mm increased up to 46°C. Owing to the uncertainty of the coefficient k, the k value of the porcine cardiac tissue varied from 160 to 220°C with temperature changes of up to 20°C. The estimated coagulation region in the ultrasound thermal imaging was 20% wider (+0.6 mm) but 9% shallower (-0.1 mm) than the measured region of the ablated porcine cardiac tissue. The current study demonstrated the feasibility of temperature monitoring with the use of ultrasound thermal imaging during the laser ablation on ex vivo porcine cardiac tissue. The high-resolution ultrasound thermal imaging could map the spatial distribution of the tissue temperature. The proposed method can be used to monitor the temperature and thermal coagulation to achieve effective laser ablation for atrial fibrillation. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.

Application of thermal tomography imaging in detection of liver injury

Objective To compare and analyze the high risk factors of liver injury, and to explore the application of thermal texture maps (TTM) technology in the diagnosis and screening of liver injury. Methods A total of 3 582 medical examiners were selected as subjects, and their general clinical data, the related physical and chemical test results and TTM results were collected. The relationship between TTM results and general clinical data and related physical and chemical results was statistically analyzed. The general clinical data and physical and chemical results of subjects with TTM negative and TTM positive liver injury were compared from the sample value statistics and the sample group comparison. Results The differences in the degree of liver damage and the main related indicators between the two groups were statistically significant (all P<0.05), except for the body mass and low-density lipoprotein cholesterol level. When using aminotransferase as the standard, the diagnostic sensitivity of TTM for liver injury was 93.18%, the specificity was 68.34%, the positive predictive value was 54.34%, and the negative predictive value was 90.32%. Conclusions TTM examination can not only reflect the state of liver injury, but also reflect the degree of injury. TTM is an important index and necessary supplement for evaluating liver injury. Key words: Thermal texture maps; Liver; Function; Injury; Metabolism

Application of thermal imaging and hyperspectral remote sensing for crop water deficit stress monitoring

Water deficit in crops induces a stress that may ultimately result in low production. Identification of response of genotypes towards water deficit stress is very crucial for plant phenotyping. The study was carried out with the objective to identify the response of different rice genotypes to water deficit stress. Ten rice genotypes were grown each under water deficit stress and well watered or nonstress conditions. Thermal images coupled with visible images were recorded to quantify the stress and response of genotypes towards stress, and relative water content (RWC) synchronized with image acquisition was also measured in the lab for rice leaves. Synced with thermal imaging, Canopy reflectance spectra from same genotype fields were also recorded. For quantification of water deficit stress, Crop Water Stress Index (CWSI) was computed and its mode values were extracted from processed thermal imageries. It was ascertained from observations that APO and Pusa Sugandha-5 genotypes exhibited the highest resistance to the water deficit stress or drought whereas CR-143, MTU-1010, and Pusa Basmati-1 genotypes ascertained the highest sensitiveness to the drought. The study reveals that there is an effectual relationship (R 2 = 0.63) between RWC and CWSI. The relationship between canopy reflectance spectra and CWSI was also established through partial least square regression technique. A very efficient relationship (calibration R 2 = 0.94 and cross-validation R 2 = 0.71) was ascertained and 10 most optimal wavebands related to water deficit stress were evoked from hyperspectral data resampled at 5 nm wavelength gap. The identified ten most optimum wavebands can contribute in the quick detection of water deficit stress in crops. This study positively contributes towards the identification of drought tolerant and drought resistant genotypes of rice and may provide valuable input for the development of drought-tolerant rice genotypes in future.

Influence of UAV flight speed on droplet deposition characteristics with the application of infrared thermal imaging

A plant protection unmanned aerial vehicle (UAV) applied for spraying pesticide has the advantages of low cost, high efficiency and environmental protection. However, the complex and changeable farmland environment is not conductive to perform spray test effectively. It is therefore necessary to carry out spray test under controlled conditions. The current study aimed to illuminate the variation law of droplet deposition characteristics under different UAV flight speeds, and to verify the feasibility for applying infrared thermal imaging in detection of droplet deposition effects. A UAV simulation platform with an airborne spray system was established and an analysis program Droplet Analysis for dealing with water-sensitive paper was developed. The results showed that, when the flight speed was set at 0.3 m/s, 0.5 m/s, 0.7 m/s, 0.9 m/s and 1 m/s, respectively, the droplet deposition density, droplet deposition coverage and arithmetic mean of droplet size D0 decreased as the UAV flight speed increased. On the contrary, the droplet diameter variation coefficient CV increased with the increase of UAV flight speed, resulting in the worse uniformity of sprayed droplet distribution as well. The results can provide a theoretical support for optimizing the spraying parameters of plant protection UAV, and demonstrate the practicability of infrared thermal imaging in evaluating the droplet deposition in the field of aerial spraying. Keywords: spray test, UAV flight speed, droplet deposition characteristics, droplet analysis, image processing, infrared thermal imaging DOI: 10.25165/j.ijabe.20191203.4868 Citation: Lv M Q, Xiao S P, Tang Y, He Y. Influence of UAV flight speed on droplet deposition characteristics with the application of infrared thermal imaging. Int J Agric & Biol Eng, 2019; 12(3): 10–17.

Field crop phenomics: enabling breeding for radiation use efficiency and biomass in cereal crops.

Plant phenotyping forms the core of crop breeding, allowing breeders to build on physiological traits and mechanistic science to inform their selection of material for crossing and genetic gain. Recent rapid progress in high-throughput techniques based on machine vision, robotics, and computing (plant phenomics) enables crop physiologists and breeders to quantitatively measure complex and previously intractable traits. By combining these techniques with affordable genomic sequencing and genotyping, machine learning, and genome selection approaches, breeders have an opportunity to make rapid genetic progress. This review focuses on how field-based plant phenomics can enable next-generation physiological breeding in cereal crops for traits related to radiation use efficiency, photosynthesis, and crop biomass. These traits have previously been regarded as difficult and laborious to measure but have recently become a focus as cereal breeders find genetic progress from 'Green Revolution' traits such as harvest index become exhausted. Application of LiDAR, thermal imaging, leaf and canopy spectral reflectance, Chl fluorescence, and machine learning are discussed using wheat and sorghum phenotyping as case studies. A vision of how crop genomics and high-throughput phenotyping could enable the next generation of crop research and breeding is presented.

Temperature profile guided segmentation for detection of early subclinical inflammation in arthritis knee joints from thermal images

In arthritis, subclinical inflammation referred to the clinical condition when rheumatologists are in confusion about the presence of inflammation using clinical and pathological observations. Application of Thermal imaging in detection of subclinical inflammation is highlighted in this literature. Segmentation of the hotspot area from the thermal image is the initial step for further analysis of the hotspot. Analysis of the hotspot will help in prediction of the subclinical inflammation, impact of inflammation. Methodologies reported in existing literature for segmentation of hotspot or inflamed knee region in medical thermal images suffer from over and under extraction.In the present scope, we try to overcome this limitation by extending the conventional region growing segmentation technique with stronger similarity criteria and stopping rule. In this method, hotspot or inflamed region is generated by taking the intersection of two independent regions produced by two different version of Region growing algorithm using a separate set of parameters. An automatic multiseed selection procedure ensures prevention of missed segmentation. We validate our technique by experimentation on various thermal image datasets like a newly created inflammatory thermal knee-joint-Database of 50 images, DBT-TU-JU Dataset, and DMR-IR Dataset. The effectiveness of the proposed technique is established compared to the performance of state-of-the-art competing methodologies.

Convolutional neural networks based potholes detection using thermal imaging

The presence of potholes on the roads is one of the major causes of road accidents as well as wear and tear of vehicles. In order to solve this problem, various techniques have been implemented ranging from manual reporting to authorities to the use of vibration-based sensors to 3D reconstruction using laser imaging. But all these techniques have some drawbacks such as the high setup cost, risk while detection or no provision for night vision. Therefore, the objective of this work is to analyze the feasibility and accuracy of thermal imaging in the field of pothole detection. After collecting a suitable amount of data containing the images of potholes under various conditions and weather, and implementing augmentation techniques on the data, convolutional neural networks approach of deep learning has been adopted, that is a new approach in this problem domain using thermal imaging. Also, a comparison between the self-built convolutional neural model and some of the pre-rained models has been done. The results show that images were correctly identified with the best accuracy of 97.08% using one of the pre-trained convolutional neural networks based residual network models. The results of this work will be helpful in guiding the future researches in this novel application of thermal imaging in pothole detection field.

Suppressing Spectral Crosstalk in Dual-Band Long- Wavelength Infrared Photodetectors With Monolithically Integrated Air-Gapped Distributed Bragg Reflectors

Antimonide-based type-II superlattices (T2SLs) have made possible the development of high-performance infrared cameras for use in a wide variety of thermal imaging applications, many of which could benefit from dual-band imaging. The performance of this material system has not reached its limits. One of the key issues in dual-band infrared photodetection is spectral crosstalk. In this paper, air-gapped distributed Bragg reflectors (DBRs) have been monolithically integrated between the two channels in long-/very long-wavelength dualband InAs/InAs1-xSbx/AlAs1-xSbx-based T2SLs photodetectors to suppress the spectral crosstalk. This air-gapped DBR has achieved a significant spectral suppression in the 4.5-7.5-μm photonic stopband while transmitting the optical wavelengths beyond 7.5 μm, which is confirmed by theoretical calculations, numerical simulation, and experimental results.