Thermal Infrared Imaging System Research Articles

Design and manufacture of a large field of view thermal infrared catoptric imaging system in an αZ configuration.

A geometry of a catoptric imaging system using three mirrors in an AlphaZ configuration is presented. This geometry allows large field of view and large aperture catoptric systems, useful for optronic pods as an example. A proof of concept with an 18×24 degree full field of view and a F/1.5 aperture is built using slow tool servo and 5 axis machining and characterized in the long wave infrared domain. The built system achieves nearly diffraction limited performance.

Digital infrared thermal imaging system based breast cancer diagnosis using 4D U-Net segmentation

Medical Research field has been taken continuous efforts to develop an efficient method for detecting breast cancer, but the goal has still not yet achieved. To overcome this issue, a 4D U-Net segmentation using digital infrared (IR) thermal imaging system is proposed in this manuscript for the diagnosis of breast cancer (DBC-4D U-Net-DITI). Initially, the digital infrared thermal images are taken from DMR-IR data set as input, and the imageries are pre-processed to maintain local features and compress the dynamic range of image based upon Altered Phase Preserving Dynamic Range Compression (APPDRC) approach by removing the speckle noise. Then, the image segmentation is carried out with the help of 4D U-Net for obtaining the segmented digital infrared thermal image. The 4D U-Net weight parameters are optimized with Glowworm Swarm Optimization Algorithm (GSOA). The segmented regions of digital infrared thermal images are fed to Binarized Spiking Neural Network (BSNN) for classifying the pathology stage as No spread, Early Stage, Localized, Regional and Distant. The proposed approach is executed in MATLAB. The performance of proposed approach attains better accuracy of 39.01%, 28.34%, and 37.45%, better precision of 17.12%, 24.12% and 32.07% when compared to existing approaches like chaotic salp swarm algorithm (CSSA) based segmentation of thermal images for breast cancer identification (DBC-CSSA-DITI), marine-predators-algorithm based segmentation of thermal images for the diagnosis of breast cancer (DBC-MPA-DITI) and diagnosis of breast cancer based upon CNN using thermal imageries (DBC-CNN-DITI) respectively.

Seasonal thermal inertia variations at Gale crater: Role of active surface deposition phenomena

Thermal inertia has been found to play a significant role in planetary remote sensing applications, forming the basis of potentially all major lithological discriminations of the planetary surface. It has always been visualised to serve as a distinctive thermal property of the surface with its values remaining fairly constant at least for a short time period, unless the surface undergoes extensive and rapid degradation. Thermal inertia for Mars has been previously calculated from point spectrometer, orbiter and rover measurements and they have been successfully used for surface geologic interpretations. The present study computes surface thermal inertia over 12 sols along Curiosity's traverse at Gale crater using Thermal Infrared Imaging System (THEMIS) and Rover Environmental Monitoring Station (REMS) observations and attempts to analyse the same on a seasonal timescale. We find that surface thermal inertia at Gale follows a seasonal sinusoidal behaviour with the surface exhibiting maximum and minimum thermal inertia values during southern autumn and spring respectively, the difference between them of the order of 300 to 400 t.i.u. We have attempted here to illustrate that the seasonal behaviour seen in surface thermal inertia may be the result of active surface deposition processes localised to Gale. In this regard, we have also explored the potential role of seasonal dust and water ice deposition in contributing to these observed variations, effectively concluding that seasonal dust deposition could be a highly likely cause to which these seasonal thermal inertia changes can be attributed to.

Detection of cervical lymph node metastasis from oral cavity cancer using a non-radiating, noninvasive digital infrared thermal imaging system

This study aimed to evaluate the diagnostic performance of a non-radiating, noninvasive infrared (IR) thermal imaging system in the detection of cervical lymph node metastasis from oral cavity cancer. In this prospective clinical trial, a total of 90 oral cavity cancer patients suspected of having cervical lymph node metastasis underwent IR imaging of the neck prior to neck dissection. Analysis of the IR images was performed by two methods: manual qualitative analysis and automatic analysis by an entropy-gradient support vector machine (EGSVM). The efficacies of the EGSVM-based infrared thermal imaging system and contrast-enhanced computed tomography (CT) were compared by using the Noninferiority Testing. Compared with manual qualitative analysis, the EGSVM-based automatic analysis had a higher sensitivity (84.8% vs. 71.7%), specificity (77.3% vs. 72.7%), accuracy (81.1% vs. 72.2%), positive predictive value (79.6% vs. 73.3%) and negative predictive value (82.9% vs. 71.1%). The EGSVM-based infrared thermal imaging system was noninferior to contrast-enhanced CT (P < 0.05). The EGSVM-based infrared thermal imaging system showed a trend of higher sensitivity, whereas contrast-enhanced CT showed a trend of higher specificity. The EGSVM-based infrared thermal imaging system is a promising non-radiating, noninvasive tool for the detection of lymph node metastasis from oral cavity cancer.

An experimental investigation of cooling characteristics at a vane end-wall with a locally enhanced hole-layout

This paper presents an experimental investigation on the effect of film hole-layout at a turbine vane end-wall on the cooling performances, including the distributions of overall cooling effectiveness, uniformity of temperature field and highest temperature drop, using a hot wind tunnel and an Infrared Thermal Imaging System (ITIS). Two specimens were manufactured and used. One is named as “uniform hole-layout (UHL)”, where ten rows of film holes were uniformly arranged along the axial direction. However, UHL results in a non-uniform temperature distribution over the entire end-wall surface, and the low film coverage and bad reliability in the regions near leading edge (LE) and pressure side (PS) of the vane thereby. To improve the cooling performance in these regions, a new layout named as “locally enhanced hole-layout (LEHL)” was proposed. The difference from the previous experiments conducted under adiabatic assumption is that, the conjugate heat transfer is considered, and the conjugate-temperature distribution is used as the basis of design of LEHL. The comparisons of the cooling performances of two specimens at various mass flow ratios (MFRs) of coolant-to-mainstream revealed that: (1) from MFR = 0.5% to 1.5%, using LEHL, the area-averaged overall cooling effectiveness over the entire end-wall, in LE region and in the corner of PS can be increased by at least 32.3%, 34.2% and 26.2%, respectively; and (2) the temperature differences from PS to suction side (SS) and the temperature at the entire end-wall can be significantly reduced by LEHL. Therefore, the design strategy of new hole-layout using the conjugate-temperature is conducive to obtain the simultaneous improvement of film coverage and working life.

An experimental investigation on the unsteady heat transfer process over an ice accreting airfoil surface

In the present study, an experimental investigation was performed in an Icing Research Tunnel available at Iowa State University (i.e., ISU-IRT) to quantify the unsteady heat transfer and dynamic ice accretion process over an airfoil/wing surface under different icing conditions (i.e., dry rime ice accretion vs. wet glaze ice accretion). A theoretic model was developed at first to evaluate the unsteady heat transfer process over the ice accreting airfoil/wing surface in the term of convective heat transfer coefficient. During the experiments, a high-speed infrared (IR) thermal imaging system was used to achieve temporally-resolved measurements of the surface temperature distribution over the ice accreting airfoil/wing surface. The transient behaviors of droplets impingement, surface water runback and dynamic phase changing processes over the airfoil/wing surface were characterized quantitatively based on the quantitative surface temperature measurements. Based on the time evolution of the measured surface temperature distributions over the airfoil/wing surface for the rime ice accretion case, the water collection efficiency distribution around the airfoil surface was determined quantitatively, which was then imported into the theoretic heat transfer model to estimate the convective heat transfer coefficients over the ice accreting airfoil/wing surface. The convective heat transfer coefficient was found to reach its maximum value at the airfoil stagnation point, and decrease gradually at the downstream locations. The formation of the ice roughness near the airfoil leading edge was found to be able to enhance the convective heat transfer process over the airfoil surface, which would further promote the ice formation and accretion over the roughed airfoil surface.

低成本红外热成像系统研制

低成本红外热成像系统研制

Experimental Study of Thermal Field Evolution in the Short-Impending Stage Before Earthquakes

Phenomena at critical points are vital for identifying the short-impending stage prior to earthquakes. The peak stress is a critical point when stress is converted from predominantly accumulation to predominantly release. We call the duration between the peak stress and instability “the meta-instability stage”, which refers to the short-impending stage of earthquakes. The meta-instability stage consists of a steady releasing quasi-static stage and an accelerated releasing quasi-dynamic stage. The turning point of the above two stages is the remaining critical point. To identify the two critical points in the field, it is necessary to study the characteristic phenomena of various physical fields in the meta-instability stage in the laboratory, and the strain and displacement variations were studied. Considering that stress and relative displacement can be detected by thermal variations and peculiarities in the full-field observations, we employed a cooled thermal infrared imaging system to record thermal variations in the meta-instability stage of stick slip events generated along a simulated, precut planer strike slip fault in a granodiorite block on a horizontally bilateral servo-controlled press machine. The experimental results demonstrate the following: (1) a large area of decreasing temperatures in wall rocks and increasing temperatures in sporadic sections of the fault indicate entrance into the meta-instability stage. (2) The rapid expansion of regions of increasing temperatures on the fault and the enhancement of temperature increase amplitude correspond to the turning point from the quasi-static stage to the quasi-dynamic stage. Our results reveal thermal indicators for the critical points prior to earthquakes that provide clues for identifying the short-impending stage of earthquakes.

Infrared thermal imaging and Doppler vessel pressurization ultrasonography to detect lower extremity deep vein thrombosis: Diagnostic accuracy study.

Infrared thermal imaging (IRTI) is a new technique for detecting deep vein thrombosis (DVT) based on DVT's infrared presentation and distribution characteristics (PDCs). A method that is singularly sensitive to DVT is needed. They, therefore, enrolled 157 subjects with suspected lower extremity DVT in a double-blind, controlled clinical trial using IRTI, and Doppler compression ultrasonography (CPUS) to verify the clinical value of IRTI. An IRTI system could precisely measure and store real-time thermal images. A double-blind, controlled clinical study using IRTI and detection on 157 patients with suspected DVTs, evaluating the following parameters: sensitivity, specificity, positive prescreening, negative prescreening, false positivity, false negativity, and diagnostic accordance of IRTI with CPUS for detecting DVT were conducted. Of 140 subjects who underwent screening both IRTI and CPUS detect were included for analyses. According to their IRTI DVT's presentation and distribution characteristics, patients were divided into IRTI- negative (n = 59) and IRTI-positive (including suspicious IRTI positive) (n = 81) groups. CPUS identified 80 DVT-negative and 60 DVT-positive patients. The sensitivity of IRTI for detecting DVT was 88.33%, specificity 65.00%, false-positive diagnosis 11.67%, false-negative diagnosis 35.00%, positive prescreening 65.43%, negative prescreening 88.14%, diagnostic accordance rate 75.00%. IRTI results accorded with CPUS results (P = .001) except for the positivity incidence (χ2 = 39.997, P < .001). IRTI could be used to supplement CPUS detection for detecting DVTs and adjunctive diagnostic screening.

Characterizing Wheat Response to Water Limitation Using Multispectral and Thermal Imaging

Abstract. Effective screening of plant genotypes for their tolerance to abiotic stress is a vital step for crop improvement. Various sensing technologies can be used for developing automated plant phenotyping systems as well as for better control of stress levels imposed on the plants. In this study, seven different wheat genotypes (G1 through G7) were grown under two different water regimes in a greenhouse. Soil moisture was monitored by soil water tension sensors distributed among the experimental plots. A sensor platform with two cameras (a multispectral camera and a thermal infrared camera) was developed to capture top-view images of the wheat plots (once a week) during the course of the experiment. Image processing algorithms were developed to extract wheat growth index (GI) and crop water stress index (CWSI). Ratios of GI and CWSI between the two water treatments were calculated as proxies to assess drought tolerance of the different genotypes. The results showed that GI was correlated with NDVI measured by a GreenSeeker sensor (R2 = 0.65). Among the seven wheat genotypes studied, G5, G6, and G7 exhibited consistently higher GI ratios and lower CWSI ratios, an indication of their superiority in drought tolerance. It was also found that non-uniform environmental conditions in the greenhouse had quite a large influence on wheat growth, which made the characterization and differentiation of phenotypes among various genotypes more challenging. It is concluded that the multispectral and thermal infrared imaging system has potential for phenotypic screening of wheat genotypes for drought tolerance in a semi-controlled environment. Keywords: CWSI, Drought, Image processing, Multispectral imaging, Phenotyping, Thermal infrared imaging.

基于海空模型的红外热成像系统成像影响分析

基于海空模型的红外热成像系统成像影响分析

An experimental investigation on transpiration cooling with phase change under supersonic condition

The extremely high heat loads on hypersonic vehicles make great challenges for the research and development of more effective Thermal Protection Technique (TPT). Transpiration cooling using liquid coolant has been confirmed as a promising TPT, because the phase change of liquid can release a large amount of latent heat. An experimental investigation on transpiration cooling using water as coolant was conducted in the arc-heated wind tunnel of China Academy of Aerospace Aerodynamics (CAAA), with a free stream specific enthalpy, mass flow rate and Mach number of 2700kJ/kg, 645g/s and 4.2, respectively. The specimen used in this experiment, a nose cone, consists of two types of materials. One is sintered porous material in the leading edge region as transpiration cooling matrix, and the other is impermeable alloy with zirconia Thermal Barrier Coating (TBC). The thermodynamic and aerodynamic parameters in coolant chamber are controlled by a quantitative injector of coolant mass flow rate to prevent the phenomena of overcooling and ablation. Surface temperature distributions are captured by an infrared thermal imaging system (ITIS). This paper exhibits and analyzes some interesting experimental phenomena, including ice formation in high enthalpy environment, hysteresis of thermal balance due to TBC, and variations of surface cooling effectiveness. A numerical approach to estimate the water mass flow rate is introduced and the relative error referenced experimental results is analyzed.

Study on the Measurement Technique of the Alignment Variation of Medical Infrared Thermal Imaging System

Study on the Measurement Technique of the Alignment Variation of Medical Infrared Thermal Imaging System

Development and evaluation of thermal infrared imaging system for high spatial and temporal resolution crop water stress monitoring of corn within a greenhouse

Inadequate water application often decreases yield and grain quality. Existing methods using single, localized soil moisture or canopy temperature measurements do not account for crop water stress on both a high spatial and temporal resolution for precision irrigation water management decisions and scheduling. Therefore, this study was conducted to understand the feasibility of thermal cameras in order to quantify high resolution spatial canopy temperatures in relation to soil moisture. The objectives of this study were to deploy a thermal infrared imaging system (TIRIS) for high spatial and temporal monitoring of corn canopy temperature in greenhouse, test camera durability and measurement accuracy during full-season crop development, remove background temperatures with image segmentation, and sample individual plants to investigate full-season crop water stress versus soil moisture content. A TIRIS was developed using a lightweight uncooled thermal camera. Corn plants were divided into well-watered and water-stressed irrigation zones to observe stress from water deficits. Canopy temperatures were used to develop empirical canopy and air temperature deficit versus vapor pressure deficit linear regressions. Results showed that the TIRIS system maintained measurement accuracy of ±0.62°C (α=0.05) while compensating for changing ambient greenhouse conditions. Canopy and air temperature deficit versus vapor pressure deficit regression equations revealed that the predicted canopy temperature was closely related to characteristic water use. Results of the 80-day study demonstrated that 82% of soil moisture variation was explained by the crop water stress index (CWSI) values between 0.6 and 1.0. Results indicated that the CWSI derived by remotely measuring canopy temperature using TIRIS can be used as an alternate irrigation scheduling method in order to quantify spatial and temporal soil moisture variability.

Infrared thermal imaging system on a mobile phone.

A novel concept towards pervasively available low-cost infrared thermal imaging system lunched on a mobile phone (MTIS) was proposed and demonstrated in this article. Through digestion on the evolutional development of milestone technologies in the area, it can be found that the portable and low-cost design would become the main stream of thermal imager for civilian purposes. As a representative trial towards this important goal, a MTIS consisting of a thermal infrared module (TIM) and mobile phone with embedded exclusive software (IRAPP) was presented. The basic strategy for the TIM construction is illustrated, including sensor adoption and optical specification. The user-oriented software was developed in the Android environment by considering its popularity and expandability. Computational algorithms with non-uniformity correction and scene-change detection are established to optimize the imaging quality and efficiency of TIM. The performance experiments and analysis indicated that the currently available detective distance for the MTIS is about 29 m. Furthermore, some family-targeted utilization enabled by MTIS was also outlined, such as sudden infant death syndrome (SIDS) prevention, etc. This work suggests a ubiquitous way of significantly extending thermal infrared image into rather wide areas especially health care in the coming time.

Preparation of ZnO:(Al, La)/polyacrylonitrile (PAN) nonwovens with low infrared emissivity via electrospinning

Polyacrylonitrile (PAN) nonwovens with infrared stealthy performance were successfully prepared via electrospinning. ZnO:(Al, La) dispersion mixed with PAN solution, then the solution was electrospun to obtain ZnO:(Al, La)/PAN nanocomposite. The infrared stealthy performance of ZnO:(Al, La)/PAN nonwovens was characterized by IR-2 dual-band infrared emissivity measuring instrument and thermal infrared imaging system. Results showed that the infrared emissivity of nonwoven fabric at the waveband 8–14µm was low to 0.793, which could be matched in the surroundings of withered grass or rock under the non-sunshine time.

The Assessment of Melanoma Risk Using the Dynamic Infrared Imaging Technique

Melanoma is the deadliest form of skin cancer. Each year more than 53,600 people learn that they have melanoma, and around 8700 people die from melanoma in the United States. Early detection is the key to improving survival in patients with malignant melanoma. We developed a thermal (infrared) imaging system that allows accurate measurements of small temperature differences on the skin surface with the aim to diagnose malignant pigmented skin lesions at an early stage of the disease. The imaging method we developed relies on active infrared imaging and a multimodal image analysis strategy, including involuntary body/limb motion correction and interactive lesion segmentation for detecting malignant lesions. The imaging system described in the paper was tested in a pilot patient study in which patients who possess a pigmented lesion with a clinical indication for biopsy were selected to participate. The lesion and the surrounding healthy skin were cooled by air at 15 °C for 30–60 s, and the thermal recovery was imaged with the infrared camera after the removal of this cooling stress. We found that the benign lesions have a thermal recovery similar to normal skin, whereas the thermal recovery of the melanoma lesion is different. It was observed that a malignant skin lesion has a higher temperature than healthy skin during the thermal recovery process (up to 2.2 °C higher for a Clark’s level II melanoma). The present study shows the feasibility of dynamic thermal imaging in distinguishing malignant pigmented lesions from benign, look-alike pigmented lesions.

Analysis of athermalizing performance of thermal infrared optical system with Cassegrain antenna

The thermal infrared imaging system is of greatest importance in modern optics and the image quality closely relies on the accuracy of the optical system. Heat-induced mirror deformation influences the transmission performance of the optical antenna system significantly, which further degrades the accuracy of the whole system. In this work, the simulation on lens deformation circumstances under the thermal environment is carried out using the finite-element analysis software ANSYS. The focus shift property caused by the thermal effect is studied in the cases of reflective and refractive Cassegrain optical antennas, and the athermalizing performance of Cassegrain optical antenna system is also concluded. This work presents a direction to accurate designing of the thermal infrared optical system.

Development of High-Speed Thermal Infrared Imaging System for Tunnel Lining

This paper describes an effort for development of a thermal imaging equipment aboard a high speed vehicle to detect anomalous regions in concrete structures of road tunnels. This type of infrared equipment would be required for the use of tunnel safety inspection with no traffic regulations on real expressways. Presented in this paper are theoretical analyses of the detection capability for inner thermal anomalies in the concrete wall, discussions on applicability of infrared detectors and on optimum scanning schemes for the imaging system, and finally, results of design and prototyping of the equipment along with field data.

Hadriaca Patera: Insights into its volcanic history from Mars Express High Resolution Stereo Camera

High Resolution Stereo Camera (HRSC) images of Hadriaca Patera, Mars, in combination with Mars Orbiter Camera (MOC), Mars Orbiter Laser Altimeter (MOLA), and Thermal Infrared Imaging System (THEMIS) data sets, reveal morphologic details about this volcano and enable determination of a chronology of the major geologic events through new cratering age assessments. New topographic measurements of the Hadriaca edifice were also made from a HRSC‐based high‐resolution (125 m) digital terrain model (DTM) and compared to the MOLA DTM. We find evidence for a complex formation and erosional history at Hadriaca Patera, in which volcanic, fluvial, and aeolian processes were all involved. Crater counts and associated model ages suggest that Hadriaca Patera formed from early shield‐building volcanic (likely explosive pyroclastic) eruptions at ∼3.7–3.9 Ga, with caldera formation no later than ∼3.5 Ga. A variety of geologic activity occurred in the caldera and on the northern flank and plains at ∼3.3–3.5 Ga, likely including pyroclastic flows (that partially filled a large crater NW of the caldera, and plains to the NE) and differential erosion/deposition by aeolian and/or fluvial activity. There were some resurfacing event(s) in the caldera and on the eastern flank at ∼2.4–2.6 Ga, in which the eastern flank's morphology is indicative of fluvial erosion. The most recent dateable geologic activity on Hadriaca Patera includes caldera resurfacing by some process (most likely differential aeolian erosion/deposition) in the Amazonian Period, as recent as ∼1.5 Ga. This is coincident with the resurfacing of the heavily channeled south flank by fluvial erosion. Unlike the Tharsis shields, major geologic activity ended at Hadriaca Patera over a billion years ago.