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An optical asymmetric encryption scheme with biometric keys
摘要： In this paper, an asymmetric cryptosystem for optical image encryption using biometric keys is proposed based on the phase retrieval algorithm and the phase-truncated Fourier transforms (PTFT) scheme which addresses the issue of key distribution with enhanced security in the optical encryption process. In the proposed system, the encryption keys include optically generated biometric keys and the random phase mask keys of the PTFT scheme, while the decryption keys are kept as the private key in terms of the binary key and the generated phase-only mask of the PTFT scheme. If a person is authorized to retrieve the biometric keys by providing the fingerprint hologram and reconstruction parameters at the receiver stage, then the proposed system satisfies the criteria of asymmetric cryptography with information authentication approach. The biometric key features, by using the digital holography are kept secure and is utilized in both the encryption and decryption operations so that the authenticity of the ciphertext by using the biometric keys can be verified during the decryption process. Numerical simulations are carried out to test the effectiveness and validity of the proposed system.
关键词： Authentication,Fingerprint biometric key,Asymmetric cryptosystem,Digital holography,Optical encryption and decryption
更新于2025-09-23 15:23:52
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Optically active polyaniline film based on cellulose nanocrystals
摘要： Chiral transfer from cellulose nanocrystals (CNCs) chiral nematic liquid crystal to polyaniline (PANI) is successfully achieved through co-assembly method for the first time, affording the PANI film based on CNCs optical activity. Meanwhile, the CNCs/PANI composite film displays notable Cotton effect ascribed to the polaron band transitions of PANI in circular dichroism (CD) spectrum. Hydrogen bond and electrostatic attraction favor the combination of two molecular chains in the mixed aqueous suspension and will lead to the chiral assembly of the PANI in the host chiral nematic film. However, the CD signal disappears when cholesteric phase collapse by acid protonation, and which demonstrates the chiral nematic ordering of the CNCs is essential to the chiral transfer. With the assistance of CNCs, PANI chains form a helically stacked structure. Thus, the optical activity of PANI originates from its long range organization.
关键词： co-assembly,chiral transfer,polaron transition,optical activity,Cotton effect
更新于2025-09-23 15:23:52
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A novel alignment procedure to assess calcified coronary plaques in histopathology, post-mortem computed tomography angiography and optical coherence tomography
摘要： Purpose: Improve mapping and registration of longitudinal view on histopathology vessels in a three-dimensional alignment procedure for postmortem quantitative coronary plaque analyses. This new procedure is applied and results shown using calcified coronary plaque analyses within post-mortem computed tomography angiography (PMCTA), optical coherence tomography (OCT) and the gold standard of histopathology. Results: In total, 338 annotated histopathology images were included, 166 PMCTA transversal images and 285 OCT images were aligned in the comparison. The results from the comparison using the alignment procedure showed overall that the calcified plaques seem to be overestimated by PMCTA and underestimated by OCT. Conclusions: The 3D fusion approach, aligning the images of PMCTA, OCT and histopathology as gold standard allowed for a slice-based comparison of the different modalities. The results showed that PMCTA overestimates the calcified plaques while OCT underestimates these, compared to histopathology.
关键词： Alignment,Calcified coronary plaques,Histopathology,Optical coherence tomography,Postmortem-computed tomography angiography
更新于2025-09-23 15:23:52
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Characterization, optical and luminescence features of cobalt ions in multi-component PbO Al2O3TeO2GeO2SiO2 glass ceramics
摘要： Glass ceramics of the composition PbOeAl2O3eTeO2eGeO2eSiO2 doped with CoO (ranging between 0 and 1.0 mol %) were prepared by melt quenching technique followed by heat treatment. The techniques such as XRD, SEM, EDS and DTA were employed for the characterization of the prepared samples. Conventional spectroscopic studies viz., optical absorption, photoluminescence, FTIR and Raman were also performed on these samples. The optical absorption spectra of the titled glass ceramics exhibited two principal absorption bands, one at about 594 nm and the second one consisting of multiplets with the meta centre at about 1455 nm ascribed to the 4A2 (4F) → 4T1 (4P) and 4A2 (4F) → 4T1 (4F) transitions of tetrahedrally coordinated Co2+ ions, respectively. Besides these, the spectra also exhibited two feeble bands at about 532 and 643 nm which are the characteristics of octahedrally coordinated Co2+ and Co3+ ions, respectively. Using Tanabe Sugano diagram the crystal field splitting parameter Dq, Racah parameters B, C and nephelauxetic ratio, β were evaluated for Co2+ ions. The photoluminescence spectra of the titled glass ceramics have exhibited two broad emission bands at 628 and 870 nm ascribed to 4T1 (4P) → 4A2 (4F) and 4T1 (4P) → 4T2 (4F) tetrahedral transitions of Co2+ ions, respectively. FTIR and Raman spectra of the titled samples exhibited various asymmetrical and symmetrical vibrational bands due to viz., silicate, germanate, PbO4, PbO6, AlO6, TeO4, TeO3 and CoIIIeO vibrations in the glass ceramic matrix. The spectroscopic investigations on the titled glass ceramics have revealed that if CoO is present in small quantities the cobalt ions predominantly occupy the octahedral sites in the glass network, whereas the tetrahedrally coordinated Co2+ ions are found to increase if the concentration of nucleating agent CoO is gradually increased up to 1.0 mol%. As a result the degree of depolymerization of the glass network decreases which in turn enhances its rigidity with increasing the concentration of nucleating agent CoO. From these investigations we report that the glass ceramics doped with 1.0 mol% of CoO are suitable for insulating devices as well as for photonic devices.
关键词： Photoluminescence,Raman spectra,XRD,Multi-component glass ceramics,SEM,Optical absorption,Cobalt ions
更新于2025-09-23 15:23:52
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Fe doping effect of vanadium oxide films for enhanced switching electrochromic performances
摘要： In the present study, Fe-doped V2O5 films showing impressive electrochromic (EC) performance were developed using the sol-gel spin-coating method. To confirm the optimized Fe-doping effect on the V2O5 films for the EC performance, we adjusted the Fe atomic percentages to 0.0, 0.5, 1.0, and 1.5 at%, respectively. With the effect of Fe doping on the V2O5 films, the obtained films resulted in the formation of the oxygen vacancies. As the result, when the optimum Fe atomic percentage was 1.0 at%, the enhanced switching speeds (3.7 s for the bleaching speed and 2.0 s for the coloration speed) and enhanced coloration efficiency value (47.3 cm2/C) compared to the other films were implemented. This can be attributed to the improved electrical conductivity and Li+ diffusion coefficient that led to efficient generation of the EC reaction activity and narrowing the optical bandgap at the coloration state to increase transmittance modulation. Therefore, this unique film can be a promising EC material to improve the performance for the EC devices.
关键词： Films,Optical properties,Transition metal oxides,Electrical properties,Electrochromic performances
更新于2025-09-23 15:23:52
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Preparation of high-quality stress-free (001) aluminum nitride thin film using a dual Kaufman ion-beam source setup
摘要： We proposed and demonstrated a preparation method of (001) preferentially oriented stress-free AlN piezoelectric thin films. The AlN thin films were deposited by a reactive sputtering technique at substrate temperatures up to 330 °C using a dual Kaufman ion-beam source setup. We deposited the AlN on Si (100), Si (111), amorphous SiO2, and a (001) preferentially oriented Ti thin film and compared their crystallographic, optical, and piezoelectric properties. The AlN thin films deposited on the (001) preferentially oriented Ti thin films have the highest crystallographic quality. The stress-free AlN reached a high value of the piezoelectric coefficient d33 = (7.33 ± 0.08) pC·N?1. The properties of the AlN thin film prepared at such low temperatures are suitable for numerous microelectromechanical systems, piezoelectric sensors, and actuators monolithically integrated with complementary metal-oxide-semiconductor signal-processing circuits.
关键词： Ellipsometry,Aluminum nitride thin film,Optical properties,d33 piezoelectric coefficient,Kaufman ion-beam source,Ion-beam sputtering deposition,(001) preferential orientation,X-ray diffraction
更新于2025-09-23 15:23:52
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Deep structure tensor graph search framework for automated extraction and characterization of retinal layers and fluid pathology in retinal SD-OCT scans
摘要： Maculopathy is a group of retinal disorders that affect macula and cause severe visual impairment if not treated in time. Many computer-aided diagnostic methods have been proposed over the past that automatically detect macular diseases. However, to our best knowledge, no literature is available that provides an end-to-end solution for analyzing healthy and diseased macular pathology. This paper proposes a vendor-independent deep convolutional neural network and structure tensor graph search-based segmentation framework (CNN-STGS) for the extraction and characterization of retinal layers and fluid pathology, along with 3-D retinal profiling. CNN-STGS works by first extracting nine layers from an optical coherence tomography (OCT) scan. Afterward, the extracted layers, combined with a deep CNN model, are used to automatically segment cyst and serous pathology, followed by the autonomous 3-D retinal profiling. CNN-STGS has been validated on publicly available Duke datasets (containing a cumulative of 42,281 scans from 439 subjects) and Armed Forces Institute of Ophthalmology dataset (containing 4,260 OCT scans of 51 subjects), which are acquired through different OCT machinery. The performance of the CNN-STGS framework is validated through the marked annotations, and it significantly outperforms the existing solutions in various metrics. The proposed CNN-STGS framework achieved a mean Dice coefficient of 0.906 for segmenting retinal fluids, along with an accuracy of 98.75% for characterizing cyst and serous fluid from diseased retinal OCT scans.
关键词： convolutional neural network (CNN),Optical coherence tomography (OCT),maculopathy,ophthalmology,graph search
更新于2025-09-23 15:23:52
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Mechanically-controllable strong 2D ferroelectricity and optical properties of semiconducting BiN monolayer
摘要： Structural, electronic, ferroelectric, and optical properties of two-dimensional (2D) BiN monolayer material with phosphorene-like structure are studied in terms of the density functional theory and modern Berry phase method of ferroelectric calculation. Both phonon spectra, molecular dynamics simulations, and total energy comparison indicate that the BiN monolayer is a stable 2D ferroelectric with polarization as large as 580 pC/m, with ferroelectric polarization being sustainable up to 500 K. Further study shows that the polarization in the BiN monolayer can be easily switched from [100] to [010] direction over the bridging saddle phase by applying a tensile [010] stress of 2.54 N/m or compressive [100] stress of -1.18 N/m. This phase transition makes its lattice constants vary in a large range compared to other non-ferroelectric 2D materials. Moreover, through applying uniaxial tensile stress parallel to the polarization, one can fix the polarization and change the semiconductor energy gap, from direct to indirect one. The optical properties feature a very strong anisotropy in reflectivity below the photon energy of 4 eV. All these significant ferroelectric, mechanical, electronic, and optical properties make us believe that the 2D BiN monolayer can be used to make stretchable electronic devices and optical applications.
关键词： 2D material,optical property,monolayer,mechanical manipulation,2D ferroelectricity,2D semiconductor
更新于2025-09-23 15:23:52
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RefMoB, a Reflectivity Feature Model-Based Automated Method for Measuring Four Outer Retinal Hyperreflective Bands in Optical Coherence Tomography
摘要： PURPOSE. To validate a model-driven method (RefMoB) of automatically describing the four outer retinal hyperreflective bands revealed by spectral-domain optical coherence tomography (SDOCT), for comparison with histology of normal macula; to report thickness and position of bands, particularly band 2 (ellipsoid zone [EZ], commonly called IS/OS). METHODS. Foveal and superior perifoveal scans of seven SDOCT volumes of five individuals aged 28 to 69 years with healthy maculas were used (seven eyes for validation, five eyes for measurement). RefMoB determines band thickness and position by a multistage procedure that models reflectivities as a summation of Gaussians. Band thickness and positions were compared with those obtained by manual evaluators for the same scans, and compared with an independent published histological dataset. RESULTS. Agreement among manual evaluators was moderate. Relative to manual evaluation, RefMoB reported reduced thickness and vertical shifts in band positions in a band-specific manner for both simulated and empirical data. In foveal and perifoveal scans, band 1 was thick relative to the anatomical external limiting membrane, band 2 aligned with the outer one-third of the anatomical IS ellipsoid, and band 3 (IZ, interdigitation of retinal pigment epithelium and photoreceptors) was cleanly delineated. CONCLUSIONS. RefMoB is suitable for automatic description of the location and thickness of the four outer retinal hyperreflective bands. Initial results suggest that band 2 aligns with the outer ellipsoid, thus supporting its recent designation as EZ. Automated and objective delineation of band 3 will help investigations of structural biomarkers of dark-adaptation changes in aging.
关键词： age-related macular degeneration,retina,ellipsoid,segmentation,optical coherence tomography,photoreceptors,interdigitation,reflectivity,retinal pigment epithelium
更新于2025-09-23 15:23:52
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Peripapillary Retinal Pigment Epithelium Layer Shape Changes From Acetazolamide Treatment in the Idiopathic Intracranial Hypertension Treatment Trial
摘要： PURPOSE. Recent studies indicate that the amount of deformation of the peripapillary retinal pigment epithelium and Bruch’s membrane (pRPE/BM) toward or away from the vitreous may reflect acute changes in cerebrospinal fluid pressure. The study purpose is to determine if changes in optic-nerve-head (ONH) shape reflect a treatment effect (acetazolamide/placebo + weight management) using the optical coherence tomography (OCT) substudy of the Idiopathic Intracranial Hypertension Treatment Trial (IIHTT) at baseline, 3, and 6 months. METHODS. The pRPE/BM shape deformation was quantified and compared with ONH volume, peripapillary retinal nerve fiber layer (pRNFL), and total retinal (pTR) thicknesses in the acetazolamide group (39 subjects) and placebo group (31 subjects) at baseline, 3, and 6 months. RESULTS. Mean changes of the pRPE/BM shape measure were significant and in the positive direction (away from the vitreous) for the acetazolamide group (P < 0.01), but not for the placebo group. The three OCT measures reflecting the reduction of optic disc swelling were significant in both treatment groups but greater in the acetazolamide group (P < 0.01). CONCLUSIONS. Change in the pRPE/BM shape away from the vitreous reflects the effect of acetazolamide + weight management in reducing the pressure differential between the intraocular and retrobulbar arachnoid space. Weight management alone was also associated with a decrease in optic nerve volume/edema but without a significant change in the pRPE/BM shape, implying an alternative mechanism for improvement in papilledema and axoplasmic flow, independent of a reduction in the pressure differential.
关键词： optical coherence tomography,Bruch’s membrane,shape analysis,papilledema,intracranial hypertension
更新于2025-09-23 15:23:52