Kieran Reeve , Nathan Dempsey , Breah Milford , Meg Willans , Brittney R. Lins , Gaewyn Ellison , Rhiannon E. Boseley , Jitraporn Vongsvivut , Mark J. Hackett , Elena Dallerba
{"title":"A comparison of synchrotron micro-FTIR spectroscopic analysis of lipid composition in frozen-hydrated and air-dried mouse brain tissue","authors":"Kieran Reeve , Nathan Dempsey , Breah Milford , Meg Willans , Brittney R. Lins , Gaewyn Ellison , Rhiannon E. Boseley , Jitraporn Vongsvivut , Mark J. Hackett , Elena Dallerba","doi":"10.1016/j.infrared.2025.106138","DOIUrl":"10.1016/j.infrared.2025.106138","url":null,"abstract":"<div><div>Sample preparation is a key consideration for FTIR spectroscopic analysis of biological cells and tissue and the effects of paraffin embedding and formalin fixation have been well studied. More recently, the effect of DNA and RNA hydration and its effect on nucleic acid absorbance bands has been studied and characterised. Surprisingly, although the effects of lipid hydration have been characterised with FTIR spectroscopy in pure lipid or model lipid bilayer systems, there has not yet been a study on the effects of lipid hydration on FTIR spectra collected from biological tissues. The X-ray fluorescence microscopy and X-ray absorption spectroscopy communities have commenced studies on the effect of tissue dehydration on the distribution and speciation of metal ions (and non-metal elements such as sulfur) in tissue samples. Therefore, the aim of this study was to investigate differences in FTIR spectra that exist when comparing frozen-hydrated tissues and air-dried dehydrated tissues, with a specific focus on lipid absorbance bands. The results highlight that not surprisingly, lipid dehydration is a key event that occurs when air-drying tissue sections, potentially removing valuable biochemical information. Through use of a temperature-controlled sample stage we demonstrate the tissues can be analysed with lipids still hydrated, in a frozen-hydrated state, which represents as close as possible to the <em>in vivo</em> condition currently achievable for organs such as brain tissue.</div></div>","PeriodicalId":13549,"journal":{"name":"Infrared Physics & Technology","volume":"151 ","pages":"Article 106138"},"PeriodicalIF":3.4,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145057091","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yongqiang Yang , Menghao Li , Wenbing Zhang , Zongqiang Sheng , Juan Gao , Hongwei Wu
{"title":"Broadband vectorial vortex filtering for edge enhancement based on spin-multiplexing metasurface in terahertz bands","authors":"Yongqiang Yang , Menghao Li , Wenbing Zhang , Zongqiang Sheng , Juan Gao , Hongwei Wu","doi":"10.1016/j.infrared.2025.106132","DOIUrl":"10.1016/j.infrared.2025.106132","url":null,"abstract":"<div><div>We propose and demonstrate an ultra-compact all-dielectric metasurface that constructs a vectorial vortex filtering system to perform broadband edge enhancement in terahertz (THz) bands. The vectorial point spread functions (PSFs) and their polarization states of the filtering system are calculated and analyzed. By controlling the polarization state of the incident THz wave, all polarization states of the vectorial PSF are achieved on the first-order Poincaré sphere. Numerical simulations show that the vectorial vortex filter can be used for selective edge enhancement when coupled with an analyzer positioned before the output plane. The orientation and anisotropy degree of selective edge enhancement can be flexibly manipulated by the polarization state of incident THz wave and the linear polarization angle of the analyzer. Our study broadens the functionality of vectorial vortex filtering systems, and the ultrathin metasurface design enables integration into optics or THz imaging systems for miniaturization.</div></div>","PeriodicalId":13549,"journal":{"name":"Infrared Physics & Technology","volume":"151 ","pages":"Article 106132"},"PeriodicalIF":3.4,"publicationDate":"2025-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145004253","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Seung-gi Gang , Ekaterina Jung , Nicholas H. Matlis , Nikola Stojanovic , Rui Pan
{"title":"Laser-free and low-jitter Electro-Optic Sampling of FEL-based THz radiation by intrinsic ultrafast laserlike-pulses at FLASH","authors":"Seung-gi Gang , Ekaterina Jung , Nicholas H. Matlis , Nikola Stojanovic , Rui Pan","doi":"10.1016/j.infrared.2025.106121","DOIUrl":"10.1016/j.infrared.2025.106121","url":null,"abstract":"<div><div>The FLASH1 THz beamline at DESY produces intense multicycle THz undulator radiation, along with quasi-single cycle edge radiation. Characterizing the temporal profile of THz radiation generated by free-electron lasers (FELs) is challenging due to unavoidable timing jitter between the THz pulse and an external laser synchronized to the FEL master clock. Although Electro-Optic Sampling (EOS) is a powerful diagnostic technique for the FEL THz sources, this jitter limits the temporal resolution and spectral bandwidth, necessitating timing jitter correction. To address this, we introduce a laser-free and low-jitter diagnostic method, Afterburner EOS (ABEOS), which uses broadband laserlike-pulses generated with the THz radiation as a probe. ABEOS results demonstrate good consistency with calculations across two probe configurations: a sequence of 10 pulses and a single pulse. Furthermore, comparisons with conventional methods of scanning EOS with an external laser, single-shot EOS (SSEOS), and FTIR show strong and reliable agreement. This technique offers ‘laser-free and low-jitter’ THz waveform characterization as a simplified, accurate, and reliable alternative to conventional THz diagnostics, validated up to 2 THz with potential for application at higher frequencies.</div></div>","PeriodicalId":13549,"journal":{"name":"Infrared Physics & Technology","volume":"151 ","pages":"Article 106121"},"PeriodicalIF":3.4,"publicationDate":"2025-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145026398","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Development and optimization of a PCA-based terahertz time-domain spectroscopy system for high-resolution material characterization","authors":"Siriwan Pakluea , Jia Yi Chia , Monchai Jitvisate , Chitrlada Thongbai , Sakhorn Rimjaem","doi":"10.1016/j.infrared.2025.106060","DOIUrl":"10.1016/j.infrared.2025.106060","url":null,"abstract":"<div><div>Terahertz time-domain spectroscopy (THz-TDS) is a powerful technique for material characterization, providing amplitude and phase information across a broad frequency range. This study details the design, development, and optimization of the first homemade THz-TDS system in Thailand, addressing the high cost and limited accessibility of commercial systems. The system features in-house-developed photoconductive antennas (PCAs) fabricated from electron-beam-irradiated SI-GaAs and a Ti:Sapphire femtosecond laser oscillator, achieving great signal-to-noise ratios and broad bandwidth. Through careful tuning of operational parameters including laser power, bias voltage, scan range, and resolution, the system achieves high signal quality and broad spectral coverage. The system’s performance was validated through material characterization experiments, including accurate measurements of refractive index and thickness of a silicon wafer. Additionally, challenges in liquid-phase measurements, such as window material selection and internal reflections, were systematically addressed. Integration of the system into a dry-air-filled box minimized moisture absorption, allowing precise characterization of moisture-sensitive materials. This work addresses critical gaps in the THz-TDS field by offering systematic system design, parameter optimization, and liquid-phase analysis. It provides practical guidelines and advancements that enable researchers to develop cost-effective, high-performance THz-TDS systems, in resource-limited settings.</div></div>","PeriodicalId":13549,"journal":{"name":"Infrared Physics & Technology","volume":"151 ","pages":"Article 106060"},"PeriodicalIF":3.4,"publicationDate":"2025-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144996908","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Use of effective medium theory for characterization of optical and dielectric properties of explosive composites in terahertz spectral range","authors":"Rajesh Koalla, Anil Kumar Chaudhary","doi":"10.1016/j.infrared.2025.106129","DOIUrl":"10.1016/j.infrared.2025.106129","url":null,"abstract":"<div><div>This paper reports the optical and dielectric characterization of highly sensitive explosives composites using an Effective Medium Theory approach in Terahertz Time-domain Spectroscopy. For the spectroscopic studies, samples need to be in pellet form. However, making pellets of some of the primary shock-sensitive high-energy materials is risky due to their sensitivity to grinding. Therefore, these sensitive samples must be mixed with an external host medium (Teflon) to form a pellet. We have approached Effective Medium Theory (EMT) analytic relations, such as Maxwell Garnett, Bruggeman, and LLL approaches, to extract the optical and dielectric properties from Teflon/ sensitive explosive composite. The approach was validated by preparing a mixture of three premium explosives, RDX, HMX, and TNT, in a Teflon matrix and extracting their optical and dielectric properties using the Effective Medium Theory method. The obtained properties of the explosives were then compared with those of the pure explosives (without the Teflon matrix). The extracted values show good agreement with those of the pure samples for the explosive mixture in the Teflon matrix (1:5).</div></div>","PeriodicalId":13549,"journal":{"name":"Infrared Physics & Technology","volume":"151 ","pages":"Article 106129"},"PeriodicalIF":3.4,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144996909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Multi-Feature joint weighted hyperspectral target detection based on optimized Gabor filter","authors":"Jiahui Wang , Fang Li , Liguo Wang , Jianjun He","doi":"10.1016/j.infrared.2025.106131","DOIUrl":"10.1016/j.infrared.2025.106131","url":null,"abstract":"<div><div>With the rapid development of hyperspectral remote sensing technology, target detection technology exhibits a wide range of application prospects in many fields. However, the detection algorithms based on raw spectral features suffer from single feature extraction and insufficient joint spatial-spectral information, leading to their poor detection performance in complex scenes. To address these issues, this paper proposes a multi-feature joint weighted hyperspectral target detection based on optimized Gabor filter. First, the conventional 3D Gabor filter is optimized through spectral angle similarity measurement, which adaptively enhances responses in target feature regions. Second, amplitude and phase information are innovatively combined, and representative feature cubes are screened based on four optimization criteria, effectively reducing data redundancy while improving feature representation capability. Finally, a weighted fusion strategy is used to integrate the four preliminary detection maps and iteratively optimized with the fuzzy Otsu algorithm, which significantly improves the detection accuracy and algorithm stability. The method proposed in this paper achieves outstanding detection performance on six hyperspectral datasets.</div></div>","PeriodicalId":13549,"journal":{"name":"Infrared Physics & Technology","volume":"151 ","pages":"Article 106131"},"PeriodicalIF":3.4,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144925467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Youtong Li , Yongyang Li , Haozhi Xu , Yanguo Guo , Wei Huang , Chen Chen , Chunguang Li , Frank K. Tittel
{"title":"Vibrating cavity off-axis integrated cavity output spectroscopy combined with new uniform phase empirical mode decomposition for CH4 measurement system","authors":"Youtong Li , Yongyang Li , Haozhi Xu , Yanguo Guo , Wei Huang , Chen Chen , Chunguang Li , Frank K. Tittel","doi":"10.1016/j.infrared.2025.106102","DOIUrl":"10.1016/j.infrared.2025.106102","url":null,"abstract":"<div><div>In order to realize CH<sub>4</sub> measurement, a vibrating cavity off-axis integrated cavity output spectroscopy (VC-OA-ICOS) CH<sub>4</sub> sensing system was developed in this paper. The inclusion of a vibration module in the system can effectively suppress cavity mode noise. To further eliminate characteristic cavity mode noise and improve system stability, we proposed a new uniform phase empirical mode decomposition (NUPEMD) method. This method enables the selection of the appropriate number of phases and the amplitude of the masking signal, thereby reducing the impacts of mode mixing and residual noise. The self-contained fitting and mutual correlation signal reconstruction technique employed in NUPEMD is particularly effective in eliminating medium- and high-frequency noise. Analysis of the Fourier frequency domain plots of the system noise revealed that the combination of vibration with the NUPEMD method significantly suppresses medium- and high-frequency residual cavity mode noise. Experimental results demonstrated that utilization of this method enabled the VC-OA-ICOS system to achieve a minimum detection limit (MDL) of 0.381 ppmv within 2 s, resulting in a 5.62-fold improvement in measurement accuracy compared to traditional methods. Furthermore, continuous measurements using this enhanced VC-OA-ICOS system on standard CH<sub>4</sub> samples over a period of 12 h yielded a long-term detection error of no more than 0.47 %, representing a 1.98-fold improvement in stability. The effectiveness and superiority of both the proposed system and the methodology for CH<sub>4</sub> measurement are thoroughly validated through these findings.</div></div>","PeriodicalId":13549,"journal":{"name":"Infrared Physics & Technology","volume":"151 ","pages":"Article 106102"},"PeriodicalIF":3.4,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145004251","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jin Shi , Pei Xiang , Shuxia Qi , Jiangluqi Song , Dong Zhao , Huan Li , Huixin Zhou , Dabao Wang
{"title":"Fast radiometric calibration and measurement technology based on distance correction in infrared systems","authors":"Jin Shi , Pei Xiang , Shuxia Qi , Jiangluqi Song , Dong Zhao , Huan Li , Huixin Zhou , Dabao Wang","doi":"10.1016/j.infrared.2025.106112","DOIUrl":"10.1016/j.infrared.2025.106112","url":null,"abstract":"<div><div>Infrared radiometric measurements can acquire important data for infrared systems. Radiometric calibration is the foundation of the measurement process. Considering the calibration issues such as gray-level drift, cumbersome calibration procedures, excessive calibration points, and high time costs in the infrared radiation measurement system when the detection distance changes, in this paper, we proposed a novel technique for fast radiometric calibration and measurement in target infrared imaging systems. First, a linear response model that correlated target radiation input with system gray value output was established. This model improves the subsequent measurement accuracy via blackbody radiometric calibration. Second, to compensate for radiation attenuation in the path and improve the measurement accuracy of the system, a radiometric calibration model based on two-test-distances was proposed. Finally, to improve the efficiency of system drift compensation, a fast radiometric calibration model was proposed by combining the radiometric calibration considering the integration time and a radiometric calibration model based on two-test-distances. The key advantage of the proposed method is that it enhances measurement accuracy by correcting the radiance measured at various test distances. The experimental results showed that the proposed method improved the calibration efficiency and measurement accuracy of the infrared radiation system. The proposed method enables measurements at different integration times and testing distances.</div></div>","PeriodicalId":13549,"journal":{"name":"Infrared Physics & Technology","volume":"151 ","pages":"Article 106112"},"PeriodicalIF":3.4,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145004252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jiawei Wu , Lailiang Song , Tianqi Li , Yang Pang , Longjie Tian , Hongcai Li , Yanqiang Yang
{"title":"Study of a multi-parameter fusion Gaussian a priori reconstruction method for hypersonic aero-radiation spectroscopy","authors":"Jiawei Wu , Lailiang Song , Tianqi Li , Yang Pang , Longjie Tian , Hongcai Li , Yanqiang Yang","doi":"10.1016/j.infrared.2025.106130","DOIUrl":"10.1016/j.infrared.2025.106130","url":null,"abstract":"<div><div>The extreme thermodynamic environment created by the high-temperature gas at the optical window in the wake of a hypersonic vehicle leads to strong aero-radiation, which causes significant background noise in star sensor observations. The study of spectral detection of aero-radiation contributes to suppress the background noise it introduces due to its spectral band characteristics. This study analyzes the spectral band characteristics of the aero-radiation spectra. Based on the theoretical framework of compressed sensing, the spectral band features are mapped to a multiple Gaussian distribution, thereby constructing a multi-parameter fused Gaussian prior model. A multi-parameter fused Gaussian prior adaptive reconstruction method is proposed. The method integrates spectral characteristics extracted from physical experimental results with mathematical modeling, enabling non-blind reconstruction of aero-radiation spectra, in which prior information—such as peak positions, widths, and intensities—is explicitly incorporated to improve reconstruction accuracy and robustness. Furthermore, a spectral goodness-of-fit evaluation criterion is proposed in this study to assess the fusion results of physical experimental spectra and simulated reconstructed spectra, serving as a standard for evaluating the quality of spectral reconstruction. The experimental results prove the effectiveness of the proposed method.</div></div>","PeriodicalId":13549,"journal":{"name":"Infrared Physics & Technology","volume":"151 ","pages":"Article 106130"},"PeriodicalIF":3.4,"publicationDate":"2025-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145095071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}