Field Of Optical Imaging Research Articles

Piezoelectric-induced mechanoluminescence in centrosymmetric Lu3Al5O12: Properties of self-recoverable and tunable near-infrared luminescence

Mechanoluminescence (ML) materials with long-wavelength emission bands are essential for future in vivo bioimaging, non-destructive testing. However, most of the near-infrared (NIR) ML materials require pre-irradiation, which may limit their further applications. Generally, piezoelectric-induced ML materials were considered to be related to the piezoelectric effect from non-centrosymmetric structure. Innovatively in this work, a novel piezoelectric-induced near-infrared ML material Lu3Al5O12:Cr3+ with centrosymmetric structure is obtained. In Lu3Al5O12:Cr3+, piezoelectric effect is generated from the distortion of the centrosymmetric structure of the host due to the uneven electron distribution of Cr3+. Here, highly tunable ML FWHM from 7 nm to 118 nm is realized by introducing different content Ga3+ ions to Lu3Al5O12:Cr3+. The ML film fabricated by composite polydimethylsiloxane and Lu3Al2Ga3O12:Cr3+ can penetrate 20 mm pork tissue, which suggests the potential applications of the NIR ML material in the field of optical imaging of stress distribution in organisms. The discovery of distorted crystal structure to induce piezoelectric effect provides a new thinking for exploring ML in centrosymmetric materials. In addition, LuAl5-xGaxO:Cr3+ phosphors have broad prospects in self-powered sensing, temporomandibular disorders diagnosis, information security, and biomedical fields.

Leukocyte detection based on convolutional neural network fusion with color Fourier ptychographic microscopy

Abstract In the field of optical microscopic imaging, color Fourier Ptychographic Microscopy (FPM) technology has attracted much attention due to its advantages of large field of view, high resolution, and quantitative phase imaging. In this paper, a color FPM fusion algorithm based on deep learning is proposed in combination with Convolutional Neural Networks (CNN) and applied to leukocyte detection. Firstly, this paper introduces a fusion model of a convolutional neural network based on the traditional color FPM imaging method and fuses low-resolution color images and high-resolution grayscale images through a multilayer convolutional network. This method improves the quality of reconstructed images while reducing the reconstruction time. Secondly, this paper constructs a leukocyte detection dataset by using an improved color FPM reconstruction algorithm and builds a leukocyte detection system based on the YOLOv7 architecture. This paper shows that combining convolutional neural networks with color FPM technology can provide higher-quality reconstructed images in medical imaging and cell detection, which provides strong technical support for digital pathology and medical diagnosis.

Robust optical singularity detection enabled by spin-synchronized shearing interference

Singular beams carrying phase and polarization singularities have been extensively studied for applications in optical communication, quantum information processing, optical imaging, and other fields. However, developing a robust method to detect optical singularity that is insensitive to wavelength, polarization, and illumination position remains a significant challenge. In this study, we propose and demonstrate a robust optical singularity detection scheme based on spin-synchronized shearing interference (SSSI) using spin-dependent gradient phase modulation of a quarter-wave liquid–crystal polarization grating. Since the spin-dependent gradient phase modulation of the polarization grating is wavelength-independent, and the two circular bases of the incident field can be measured simultaneously, the proposed method is robust to wavelength and polarization. Additionally, we have verified that SSSI performs well in detecting multi-singularity cylindrical vector beam. This work provides a practical and straightforward scheme for robust optical singularity detection.

A tutorial on optical photothermal infrared (O-PTIR) microscopy.

This tutorial reviews the rapidly growing field of optical photothermal infrared (O-PTIR) spectroscopy and chemical imaging. O-PTIR is an infrared super-resolution measurement technique where a shorter wavelength visible probe is used to measure and map infrared (IR) absorption with spatial resolution up to 30× better than conventional techniques such as Fourier transform infrared and direct IR laser imaging systems. This article reviews key limitations of conventional IR instruments, the O-PTIR technology breakthroughs, and their origins that have overcome the prior limitations. This article also discusses recent developments in expanding multi-modal O-PTIR approaches that enable complementary Raman spectroscopy and fluorescence microscopy imaging, including wide-field O-PTIR imaging with fluorescence-based detection of IR absorption. Various practical subjects are covered, including sample preparation techniques, optimal measurement configurations, use of IR tags/labels and techniques for data analysis, and visualization. Key O-PTIR applications are reviewed in many areas, including biological and biomedical sciences, environmental and microplastics research, (bio)pharmaceuticals, materials science, cultural heritage, forensics, photonics, and failure analysis.

DLP-Fusion: Depth of Field, Light Source, and Polarization Fusion Toward Intelligent Optical Imaging for Complex Scenes

DLP-Fusion: Depth of Field, Light Source, and Polarization Fusion Toward Intelligent Optical Imaging for Complex Scenes

Image reconstruction through a nonlinear scattering medium via deep learning

Image reconstruction through the opaque medium has great significance in fields of biophotonics, optical imaging, mesoscopic physics, and optical communications. Previous researches are limited in the simple linear scattering process. Here, we develop a nonlinear speckle decoder network, which can reconstruct the phase information of the fundamental frequency wave via the nonlinear scattering signal. Further, we validate the ability of our model to recover simple and complex structures by using MNIST and CIFAR data sets, respectively. We then show that the model is able to restore the image information through different sets of nonlinear diffusers and reconstruct the image of a kind of completely unseen object category. The proposed method paves the way to nonlinear scattering imaging and information encryption.

Design of tunable selective light-absorbing metasurfaces driven by intrinsically chiral quasi-bound states in the continuum.

Chiral metasurfaces with high quality factors (Q-factors) and strong circular dichroism (CD) are excellent platforms for studying chiral optical response. Here, a design is proposed of an intrinsic chiral silicon metasurface driven by bound states in the continuum (BIC), with ultra-high Q-factor (Q = 3722) and chirality response close to the unit CD (CD > 0.99). By breaking the in-plane and out-of-plane symmetry of the structure, the intrinsic chirality based on BIC can be precisely controlled. In addition to studying intrinsic chirality, we have also achieved extrinsic chirality by obliquely incident circularly polarized light without introducing out-of-plane asymmetry. Moreover, we introduce graphene into the intrinsically chiral metasurface to form a graphene-Si hybridized metasurface. Selective absorption of intensity-controlled right-handed/left-handed circularly polarized light (RCP/LCP) was achieved by actively tuning the Fermi level and out-of-plane tilt angle of the graphene structure based on coupled-mode theory. Our research provides another insight into the application of intrinsic optical chirality, which is expected to be widely used in the fields of optical filters, polarization detectors, and chiral imaging.

Ring-shaped segmentation phase design method for the combined point spread function.

The study presents a method for designing phase masks, specifically the ring-shaped segmentation method, which can be employed in creating the modulation phase for specialized point spread functions (PSFs), such as multi-focus PSFs and those with axial encoding functions. An algorithm for phase inversion optimization is introduced to enhance the optical transfer function efficiency of the designed phase mask, which is based on the Fresnel approximation imaging inverse operation and iterative Fourier transform algorithm. The ring-shaped segmentation phase design approach effectively combines individual phases, resulting in unified PSFs with unique properties. The promising outcomes demonstrated by the designed PSFs are truly remarkable. The refined phase masks and experimental verification further validate the effectiveness of this groundbreaking approach. This advancement in ring-shaped segmentation method development has significant potential for real-world applications, representing a noteworthy contribution to the field of optical imaging.

Miniature snapshot mid-infrared spectrometer based on metal-insulator-metal metasurface

Metasurfaces showcase the performance of light field manipulation at the subwavelength scale, generating tremendous applications in the field of optical imaging and sensing, especially in spectroscopic detection. Here, we demonstrate a spectral detector comprising metal-insulator-metal composite structures working in the mid-infrared band, which can effectively collect and restore target spectral characteristics in the mid-infrared band with a trained reconstruction algorithm. The proposed device consists of snapshot multichannel detection and spectral reconstruction, showing an average spectral reconstruction accuracy approaching 80% of the system. Moreover, we discuss the feasibility of applying this structural design to a miniature spectrometer over a wider infrared wavelength range by proposing a feasible design strategy. Our results provide a novel approach for low-cost and portable mid-infrared spectroscopic detection in ultracompact mid-infrared spectral imaging and sensing elements.

Fractional fourier transform and its application

The Fourier Transform (FT) is a linear transformation for the primitive function. It takes some set of functions to be an orthogonal basis. Its physical meaning is to transfer the primitive function onto each set of base functions. Because it can convert functions between the time and frequency domains, the FT is widely employed in many fields. The Fractional Fourier Transform (FrFT) is an improvement and progress based on the FT. This paper will define the FT and FrFT. Then the distinction between FrFT and FT is discussed. Finally, specific examples of its application in processing digital image are provided. FrFT is the process of transforming an image function into a series of periodic functions. The FrFT is used as a powerful mathematical tool to understand non- smooth signals, nonlinear systems and complicated phenomena, which is significant and has broad possibilities in the fields of signal processing, communication, image processing, optical imaging and quantum information processing.

Upgraded and Light-Up Biosensing Platform: Entropy-Driven Catalysis Circuit Manipulates the Configuration Transformation of Novel DNA Silver Nanoclusters on the Graphene Oxide Surface.

To tackle the predicament of the traditional turn-off mechanism, exploring an activated turn-on system remains an intriguing and crucial objective in biosensing fields. Herein, a dark DNA Ag nanocluster (NC) with hairpin-structured DNA containing a six-base cytosine loop (6C loop) as a template is atypically synthesized. Intriguingly, the dark DNA Ag NCs can be lit to display strong red-emission nanoclusters. Building upon these exciting findings, an unprecedented and upgraded turn-on biosensing system [entropy-driven catalysis circuit (EDCC)-Ag NCs/graphene oxide (GO)] has been created, which employs an EDCC to precisely manipulate the conformational transition of DNA Ag NCs on the GO surface from adsorption to desorption. Benefiting from the effective quenching of GO and signal amplification capability of the EDCC, the newly developed EDCC-Ag NCs/GO biosensing system displays a high signal-to-background (S/B) ratio (26-fold) and sensitivity (limit of detection as low as 0.4 pM). Meanwhile, it has good specificity, excellent stability, and reliability in both buffer and biological samples. To the best of our knowledge, it is the first example that adopts an EDCC to precisely modulate the configuration transformation of DNA Ag NCs on the GO surface to obtain a biosensor with low background, strong fluorescence, high contrast, and sensitivity. This exciting finding may provide a new route to fabricate a novel turn-on biosensor based on hairpin-templated DNA Ag NCs in the optical imaging and bioanalytical fields.

Abstract PO1-07-08: Value of high resolution full field optical coherence tomography and dynamic cell imaging (D-FFOCT) for one-stop rapid diagnosis breast clinic

Abstract BACKGROUND: Full field optical coherence tomography combined to dynamic cell imaging (D-FFOCT) is a new, simple to use, nondestructive, quick technique than can provide sufficient spatial resolution to mimic histopathological analysis. The objective of this study was to evaluate diagnostic performance of D-FFOCT for one-stop rapid diagnosis breast clinic. METHODS: D-FFOCT was applied to fresh untreated breast and nodes biopsies. Four different readers (senior and junior radiologist, surgeon and pathologist) analyzed the samples without knowing final histological diagnosis or ACR classification. The results were compared to conventional processing and staining (Hematoxylin-eosin). RESULTS: A total of 217 biopsies were performed on 152 patients. There were 144 breast biopsies and 61 lymph nodes with 101 infiltrative cancers (49,27%), 99 benign lesions (48,29%), 3 ductal in situ carcinoma (1,46%) and 2 atypias (0,98%). The diagnostic performances results were as follow: sensitivity: 77% [0.7;0.82], specificity: 64% [0.58;0.71], PPV: 74% [0.68;0.78] and NPV: 75% [0.72;0.78]. A large images atlas was created as well as a diagnosis algorithm from the readers experience. CONCLUSION: D-FFOCT provides interesting results defining malignancy on fresh breast and nodes samples. By training with the diagnosis algorithm and the images atlas or by using machine learning, radiologists could obtain even better outcomes allowing quick detection of breast cancer and lymph node involvement. diagnosis algorithm Figure 1 Images in DCI and FFOCT Two infiltrating cancer diagnosed on pathology (A,B). Focusing on cells (C). Normal galactophoric duct (D). Adenofibroma (E) Citation Format: Alexis Simon, Yasmina Badachi, Jacques Ropers, Isaura Laurent, Lida Dong, Elisabeth Da Maia, Agnes Bourcier, Geoffroy Canlorbe, Catherine Uzan. Value of high resolution full field optical coherence tomography and dynamic cell imaging (D-FFOCT) for one-stop rapid diagnosis breast clinic [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-07-08.

A highly stable, accurate and fast photo-response in visible region: Role of introducing Ta2O5 /MWCNTs heterostructures in photodetector

This work presents the development of a novel photodetector design that leverages the synergistic combination of tantalum pentoxide (Ta2O5) and multi-walled carbon nanotubes (MWCNTs) to achieve superior visible light detection performance. Ta2O5/MWCNT heterostructures were synthesized and comprehensively characterized using various techniques. Structural, morphological, and optical analyses confirmed the suitability of these heterostructures for the targeted application. Photoluminescence spectroscopy was further employed to meticulously assess defect levels, which play a crucial role in photodetector performance. The photodetectors were fabricated using pure Ta2O5, pure MWCNTs, and the synthesized Ta2O5/MWCNT heterostructures. When subjected to different illumination wavelengths and voltages, the Ta2O5/MWCNT devices demonstrated significantly enhanced visible light detection and photocurrent compared to their individual counterparts. The measured responsivity, detectivity, and quantum efficiency of the Ta2O5/MWCNT photodetectors were highly impressive, reaching 81 mA/W, 16.38 × 106 Jones and 15.5 %, respectively. Critically, the fabricated photodetectors exhibited exceptional stability with rapid response times, characterized by an 80-ms rise and recovery cycle. This fast response characteristic underscores the potential of Ta2O5/MWCNT photodetectors in applications demanding high-speed and precise optical signal detection, such as those found in the fields of optical communication, sensing, and imaging.

Aberration correction by polynomial approximation for synthetic aperture ultrasound imaging

AbstractBackgroundPreviously, there has been some work in the field of optical imaging on phase compensation by employing Legendre polynomials as an expansion of the phase function, and this seems to be an appealing unstudied area in the field of ultrasound imaging.PurposeThe paper is devoted to solving one of the problems of enhancing the authenticity of diagnostics data obtained in ultrasound visualization systems and presents a novel approach to aberration correction, which ensures a reliable eliminating of phase distortions. The novelty of the proposed approach consists in the use of the decomposition of the wave front by Legendre polynomials to approximate aberrations of the phase front of ultrasonic waves propagating through distorting layers.MethodsThe phase aberrations are corrected using a single sector probe that captures echoes in synthetic aperture mode. The proposed method approximates the changes in the wave front by means of the Legendre polynomials. The performance was investigated by placing a 13‐mm‐wide ultrasonic probe with 64 elements operating at 2 MHz on the surface of a commercial quality control phantom ATS Model 539 through a distorting layer. The following metrics were measured: peak value, root mean square (RMS), full width at half maximum (FWHM), contrast‐to‐noise ratio (CNR). During the experiments, three different aberrators were used interchangeably as distorting layers, two of which were made of photopolymer resin with RMS values of 39 and 97 ns and a speed of sound close to that of a human temporal bone tissue, and the third was an ex vivo human temporal bone with the RMS value of 44 ns. To test the correction, three regions inside the phantom were examined. Two‐sided nonparametric Wilcoxon rank‐sum test was used for assessing the statistical significance. The significance level for this study was set at α ≤ 0.05. To counteract the problem of multiple comparisons, the p‐values were adjusted by the Holm–Bonferroni correction method.ResultsThe statistically significant results have demonstrated the possibility of increasing peak intensity value up to 3.08 times, reducing the RMS width and FWHM of the intensity angular distribution down to 60% and 82%, respectively, and increasing CNR up to 2.12 times by using the proposed phase distortion correction method, compared with the case without correction. The results show that the method can be used as an effective aberration correction technique for all tested regions inside the phantom and distorting layers. Its usage allowed correcting up to 97% of the aberrations caused by the ex vivo temporal bone model.ConclusionThe results show that the usage of the proposed method for aberration correction can successfully increase the intensity and reduce the angular width of the ultrasound wave scattered by the point targets inside the phantoms. The method works with different distorting layers and is capable of correcting phase aberrations in multiple sections of the sonogram. The limitation of the proposed method consists in the fact that it requires the use of aperture synthesis and access to raw radiofrequency data, which restricts its application in common scanners.

Reduction of oxygen vacancies in Mg–N codoped Ga2O3 films for improving solar-blind UV photodetectors performance

Solar-blind photodetectors based on gallium oxide (Ga2O3) have shown possibilities in optical imaging, spatial communication, and other fields. The high oxygen vacancy (VO) content inherent in Ga2O3 film would inevitably result in poor photoelectric detection capability. This work suggests using a codoping for reducing VO concentrations in Ga2O3 films. In a N2O atmosphere, magnesium and nitrogen codoped gallium oxide (Mg–N:Ga2O3) films were grown using the pulsed laser deposition (PLD) technique on (0001) sapphire substrates. It is possible to produce codoped Ga2O3 thin films with low oxygen vacancy density and high crystalline quality by thoroughly examining and optimizing preparation conditions. Metal-semiconductor-metal (MSM) photodetectors were constructed using both pristine and Mg–N codoped Ga2O3 thin films as the active layer. The photodetector with a codoped active layer outperforms those with pristine Ga2O3, with a quick decay time of 20 ms, a high sensitivity of 2.61 × 105, and a high responsivity of 0.191 A/W under 254 nm UV light irradiation, highlighting the significance of the VO concentration decrease in the application of Ga2O3-based solar-blind photodetectors.

Deep‐subwavelength characteristics of focused vector double‐petal linear edge dislocation beams

AbstractRecently, vector beams with special intensity and phase distribution have received much attention due to their unique properties. In this paper, we construct the double‐petal linear edge dislocation (DPLED) beams based on Gaussian vortex beams. The distribution of intensity, polarization, and spin angular momentum (SAM) of the DPLED beams is analyzed in tightly focused based on the Richards‐Wolf vector diffraction theory. The significant difference is occurred in light field, polarization SAM, and polarization distributions before and after focusing of DPLED beams. It's of certain importance for expanding the application of vector beams in optical control, optical imaging, and other fields.

Mechanistic Insights into the Bacterial Luciferase-based Bioluminescence Resonance Energy Transfer Luminescence: The Role of Protein Complex Dimer.

Bacterial bioluminescence holds significant potential in the realm of optical imaging due to the inherent advantages of bioluminescence and ease of operation. However, its practical utility is hindered by its low light intensity. The fusion of bacterial luciferase with a highly fluorescent protein has been demonstrated to significantly enhance autonomous luminescence. Nevertheless, the underlying mechanism behind this enhancement remains unclear, and there is a dearth of research investigating the mechanistic aspects of bioluminescence resonance energy transfer (BRET) luminescence, whether it occurs naturally or can be achieved through experimental means. In this study, we investigated the phenomenon of bacterial luciferase-based BRET luminescence employing a range of computational techniques, including structural modeling, molecular docking, molecular dynamics simulations, as well as combined quantum mechanics and molecular mechanics calculations. The theoretical findings suggest that the BRET luminescence occurs through resonance energy transfer between the excited bioluminophore and the ground chromophore within the protein complex dimer. The proposed mechanism of the protein complex dimer offers a microscopic understanding of the intriguing BRET phenomenon and has the potential to inspire further practical applications in the field of optical imaging.

Gate tunable linear dichroism in monolayer 1T'-MoS2.

The linear dichroism demonstrates promising applications in the fields of polarization-resolved photodetectors and polarization optical imaging. Herein, we study the optical properties of monolayer 1T'-MoS2 based on a four-band effective k · p Hamiltonian within the framework of linear response theory. Owing to the anisotropic band structure, the k-resolved optical transition matrix elements associated with armchair(x) and zigzag(y) direction polarized light exhibit a staggered pattern. The anisotropy of the optical absorption spectrum is shown to sensitively depend on the photon energy, the light polarization and the gate voltage. A gate voltage can continuously modulate the anisotropy of the optical absorption spectra, rendering it isotropic or even reversing the initial anisotropy. This modulation leads to linear dichroism conversions across multiple wavelengths. Our findings are useful to design polarized photodetectors and sensors based on monolayer 1T'-MoS2. Our results are also applicable to other monolayer transition metal dichalcogenides with 1T' structure.

Intensity controlled and multi-multiplexed full-space achromatic metalens and modulated orbital angular momentum.

The Fabry-Perot (F-P) interference model was used to make a 6-layer metasurface with cross-polarization that can be changed by heat. The fundamental concept behind the metasurface is to utilize the selectivity of linearly polarized waves by a metal grating to achieve broadband and efficient polarized conversion (PC). It also uses the thermal conversion properties of vanadium dioxide (VO2) to control the amplitude of terahertz (THz) waves in a dynamic way. While achromatic metalenses have been extensively studied, altering the entire spatial incidence angle remains relatively uncommon. Enter modulated orbital angular momentum (MOAM), a promising approach for applications such as holographic encryption, optical communication, and imaging. However, achieving MOAM multidimensional multiplexing has proven to be a significant challenge. In response to this challenge, we have integrated the transmission phase into the metasurface design. This new idea makes it possible to make a full spatially achromatic metalenses with angular multiplexing and makes MOAM multidimensional multiplexing easier by letting you switch between frequency, angle, and MOAM modes. This pioneering approach unveils new prospects for enhancing the capacity, rate, and quality of information exchange in domains such as optical encryption, optical imaging, optical communication, and other related technological fields.

Hydrothermal synthesis of ZnGa2O4 nanophosphors with high internal quantum efficiency for near-infrared pc-LEDs.

NIR luminescent materials have garnered widespread attention because of their exceptional properties, with high tissue penetration, low absorption and high signal-to-noise ratio in the field of optical imaging. However, producing nanophosphors with high quantum yields of emitting infrared light with wavelengths above 1000 nm remains a significant challenge. Here, we prepared a nanoscale ZnGa2O4:xCr3+,yNi2+ phosphor with good luminescence performance in near-infrared emission, which was synthesized via a hydrothermal method and subsequent calcination process. By co-doping with Cr3+ and Ni2+, the ZnGa2O4 phosphor shows a strong broadband emission of 1100-1600 nm in the second near-infrared (NIR-II) region, owing to the energy transfer from Cr3+ to Ni2+ with an efficiency up to 90%. Meanwhile, a near-infrared phosphor-conversion LED (NIR pc-LED) device is fabricated based on the ZnGa2O4:0.8%Cr3+,0.4%Ni2+ nanophosphor, which has under 100 mA input current, an output power of 23.99 mW, and a photoelectric conversion efficiency of 7.53%, and can be effectively applied in imaging and non-destructive testing. Additionally, the intensity ratio of INi/ICr of ZnGa2O4:0.8% Cr3+,0.4%Ni2+ with its high sensitivity value of 4.21% K-1 at 453 K under 410 nm excitation, indicates its potential for thermometry application.