Search Results (439)

Optical imaging is among the safest and most highly impactful biomedical imaging modalities. Aberration in optical imaging systems leads to distorted images. This distortion is almost nonlinear and hence affects the relative size, intensity and appearance of image details. Image aberration has many types, with some or all of them able to be imposed on the image based on the quality of the imaging system and/or surrounding conditions. Many approaches have been introduced to remove or minimize aberration from optical images. If the transfer function of an imaging system and the function of the noise added during the imaging process are known, then an ideal image can be obtained from the image produced by this system. The point spread function (PSF) of an optical imaging system is the image it produces for a point object. PSF is the observable form of the transfer function. The transfer function itself is the exit pupil function or typically the system aberration. The nonlinearity and multiplicity of the aberration imposed on the image, together with the added noise, make it difficult to obtain the transfer function from the degraded images. In this work, optimization and global search techniques are utilized in an iterative image restoration algorithm to estimate the transfer function and restore the image. The proposed technique updates an initially suggested solution of transfer function by optimizing the aberration coefficients. The final solution of the transfer function and hence the PSF is reached when the optimum restored image is obtained. The proposed algorithm is validated by a set of 12 images degraded by different combinations of aberration patterns. Many statistical metrics are used to assess the performance of the proposed algorithm, resulting in a 100% success rate with SSIM equals 1 and a MAE range from 0 to $1\times {10}^{-8}$. Full article

To address the erosion-induced failure of large-caliber gun barrels under extreme thermochemical coupling, this study systematically investigates the microstructural evolution of multi-layered gradient regions along the radial direction of 32CrNi3MoV steel under extreme thermochemical cycling. Leveraging SEM, EBSD, TKD, and double-beam aberration-corrected TEM, combined with JMatPro thermodynamic simulations, the phase transitions, crystallographic characteristics, and substructural evolution spanning from the bore surface to the matrix are elucidated. The results demonstrate that a three-layer gradient structure forms along the radial direction. The topmost layer is a chemically stabilized metastable austenite diffusion layer with a thickness of 1.5–4.0 μm. which is attributed to the suppression of martensitic transformation due to C/N interstitial diffusion lowering the MS temperature. The observed high-density dislocation tangles and stacking faults within this austenite diffusion layer result from thermal mismatch stresses during rapid thermal cycling. The subsurface region is a martensitic transformation layer with a thickness of 70–97 μm, exhibiting a substructural gradient from nanostructured high-density twinned martensite to refined lath martensite. Thermodynamic analysis indicates that rapid heating (≈10⁵ °C/s) facilitates significant austenite nucleation and growth during the reverse phase transformation, subsequently forming nanostructured martensitic grains via non-equilibrium transformation during rapid cooling. Adjacent to this is a matrix tempering layer extending approximately 160 μm. Nanoindentation hardness profiling reveals that the peak radial hardness (≈1000 HV) occurs within the fine-grained martensitic zone approximately 40 μm from the surface. In contrast, the tempered layer exhibits reduced hardness (≈400 HV) compared to the original matrix (≈500 HV). This is primarily attributed to transient high-temperature over-tempering effects, which induces carbide coarsening and the loss of solid solution strengthening, alongside the softening of prior austenite grain boundaries. This study clarifies the micro-to-nanoscale evolution of the barrel microstructure, providing critical theoretical insights for understanding erosion mechanisms and improving lifetime predictions. Full article

In this work, an adaptive Hartmann–Shack wavefront sensor (AHSS) is proposed, designed, and evaluated. This sensor allows for the modification in the dynamic range of wavefront aberration measurement, defined as the range between the minimum and maximum aberration value that can be measured with the sensor. This capability makes it suitable for studying optical aberrations in both objective systems and the human eye. AHSS consists of sixteen phase profiles corresponding to microlens arrays designed to be projected (one at a time) onto a spatial light modulator (SLM). In each design, the microlens size and focal distance parameters were varied. A calibration process was conducted, and aberration measurements were made in both artificial and real eyes. The results demonstrate good correspondence between the measurements with the AHSS and a conventional Hartmann–Shack sensor, which uses an actual refractive microlens array with fixed size and focal length parameters, proving their feasibility for measuring optical aberrations. The AHSS opens up possibilities for measurements in eyes with special characteristics, such as high aberrations, and enables the implementation of active optics aberration correction systems without the need for an additional refractive (physically lensed) wavefront sensor. Full article

Scleral lenses (SLs) are increasingly incorporating complex optical designs, including front surface eccentricity (FSE) optimisation and wavefront-guided (WFG) corrections, to address residual higher-order aberrations (HOAs) in eyes with irregular corneas. Accurate in vitro optical verification of these surfaces relies on Hartmann–Shack (HS) metrology systems, yet commercially available devices differ substantially in lenslet array spatial sampling density, raising questions about their interchangeability for quality control purposes. This study evaluated the repeatability and inter-device agreement of HOA measurements in SLs obtained with two HS metrology systems with substantially different spatial sampling resolution. Sixteen SLs (four symmetric spherical, four spherical with toric periphery, four symmetric aspherical, four aspherical with toric periphery) were measured three times each using the SHSOphthalmic Cito (54 × 54 lenslet array) and SHSInspect Prio (157 × 157 lenslet array). Sphere (D) and Zernike coefficients from third to fifth radial orders were extracted for three aperture diameters (3.00, 5.00, and 7.00 mm) and analysed as root-mean-square (RMS) values by radial order and as Total HOA RMS. Both devices demonstrated excellent within-device repeatability for Sphere, RMS4, and Total HOA RMS (ICC: 0.994–1.000, CV ≤ 4%), while RMS3 and RMS5 showed moderate repeatability (ICC: 0.591–0.964, CV: 7–21%). Inter-device agreement was excellent at 5.00 and 7.00 mm (ICC: 0.950–1.000, mean bias < 0.006 μm), with a significant difference only for RMS3 at 7.00 mm aperture (p = 0.034). At 3.00 mm, significant systematic bias was detected for RMS4 (bias = −0.00102 μm, p < 0.001) and Total HOA RMS (bias = −0.00092 μm, p < 0.001), with the Cito underestimating values relative to the Prio. FSE design did not significantly influence inter-device differences. HS spatial sampling density influences HOA measurement accuracy in SLs at small apertures, and standardised high-resolution metrology protocols are essential to ensure accurate HOA characterisation. Full article

The growing global protein demand and environmental concerns from conventional animal agriculture have driven the exploration of sustainable alternative protein sources. Single-cell proteins (SCPs) from microbial fermentation offer a promising solution. This study comprehensively evaluated the nutritional value and safety profile of SCP produced from Ralstonia eutropha H16 through integrated in vitro and in vivo assessments. Nutritional analyses revealed a high crude protein content of 71.87 ± 5.05 g/100 g dry weight, with total amino acids of 53.67 ± 1.05 g/100 g. The essential amino acid content was 24.38 ± 0.51 g/100 g, accounting for 45% of the total amino acids. An essential amino acid index (EAAI) of 1.46 ± 0.04 and an amino acid score (AAS) of 0.83 ± 0.06 confirmed its classification as a high-quality protein source according to FAO/WHO standards. In vivo rat feeding trials demonstrated an adjusted protein efficiency ratio (PER) of 1.81, exceeding common plant proteins such as wheat (0.8–1.1). True digestibility (TD) reached 85.73%, with a biological value (BV) of 49.37%, net protein utilization (NPU) of 42.33%, and protein digestibility-corrected amino acid score (PDCAAS) of 0.71. Comprehensive safety assessments included chemical contaminant screening, acute oral toxicity studies in rats and mice, in vitro chromosome aberration tests, and erythrocyte micronucleus tests. Heavy metals and aflatoxin B₁ levels were below regulatory limits. Acute oral toxicity studies established LD₅₀ values exceeding 10,000 mg/kg body weight in both rodent species, classifying this protein source as practically non-toxic. The 28-day sub-acute toxicity study showed no significant adverse effects at low doses (6.25% protein replacement). Both genotoxicity assays (mammalian cell chromosome aberration assay and mammalian erythrocyte micronucleus test) returned negative results. These findings establish R. eutropha H16-derived SCP as a safe, nutritious, and sustainable protein source with considerable potential for feed and food applications, contributing to global food security and environmental sustainability. Full article

Breast cancer is one of the most devastating malignancies in women worldwide. A growing body of evidence has linked neoplastic growth, invasion, metastasis, immune escape, and therapeutic resistance to infiltrating tumor-associated macrophages. In a breast cancer mass, macrophages are largely polarized to two main subtypes, M1 and M2, albeit with continuum intermediates, based on their immunological behaviors, gene signatures, and functional roles. While the former portrays proinflammatory and anti-cancer effects, the latter elicits the opposite impacts. M2 macrophages have gained rising attention as they are largely involved in fostering an immune-suppressive, cancer-promoting landscape and are imperative for malignant features across breast cancer subtypes. Through a positive feedback paracrine loop, M2 macrophages can be enriched by a plethora of dysregulated oncogenic signaling mediators, exemplified by CSF1/CSF1R, STAT3, IL-6, YAP, PI3K, PDK1, and AKT. These modulators could be released from or activated by surrounding malignant cells, fibroblasts, secreted extracellular vesicles, cell fragments generated after chemotherapies, hypoxia, dysregulated immune checkpoint pathways or oncometabolites. This review aims to discern the molecular cues fortifying M2 subpopulations. Moreover, recent advances in single-cell sequencing, spatial, and computational approaches have refined the understanding of TAM heterogeneity, while clinical translation remains limited by low therapeutic specificity, compensatory signaling, and differences between murine and human macrophage biology. Future therapeutic regimens should include strategies aimed at correcting aberrations that favor M2 polarization and are justified with divergences between humans and mice. Full article

Metal carbides (MCs) serve as essential strengthening phases in nickel-based superalloys, so the decomposition of MCs during high-temperature creep is regarded as detrimental to the mechanical properties and service life of these alloys. However, detailed investigations of the MC decomposition process at the microscale remain limited. In this study, the microstructure of MCs (where M is a mixture of Ti and Ta) in a nickel-based superalloy was characterized using aberration-corrected scanning transmission electron microscopy. The MCs exhibit a spherical core–shell structure, with Ta enrichment in the shell and Ti segregation in the core. Moreover, a high density of Cr-rich stacking faults, accompanied by Cr-rich M₂₃C₆ precipitates at their terminations, was identified in the Ti-rich cores, suggesting that these defects may be closely associated with the decomposition of MCs. This study may further expand the fundamental understanding of the interactions between defects and carbide properties. Full article

This paper addresses the chromatic aberration and off-axis collimation issues in the laser–lens–fiber coupling system by proposing a chromatic aberration-corrected Meta-lens design based on a particle swarm optimization algorithm and structural interleaving method. By establishing an optimization model that includes wavelength-dependent phase factors, achromatic performance with a focal length standard deviation of less than 0.4 μm is achieved in the 1260–1360 nm band. Innovatively, the structural interleaving technique is adopted to integrate multiple different phase distributions into a single meta-surface, keeping the coupling efficiency fluctuation within 8% over a ±1 μm off-axis displacement range. The research results demonstrate that this method effectively solves the phase quantization and dispersion matching challenges of large-scale meta-lens, achieving a phase matching efficiency of 95.2%, providing a feasible path for the engineering application of highly robust meta-lens in high-precision optical systems. Full article

Chromatic aberration correction remains a major challenge in dual-band infrared continuous zoom optical systems. To address this issue, an achromatic design method based on the equivalent refractive index and equivalent dispersion rate is proposed. Starting from a four-component continuous zoom model, chromatic compensation is introduced into the initial structural parameter calculation, and the initial structural parameters are obtained through an iterative procedure. To validate the proposed method, a MWIR/LWIR dual-band continuous zoom optical system is designed. The final system covers the MWIR (3.7–4.8 μm) and LWIR (8–10 μm) bands with a focal length range of 10–120 mm, and the chromatic focal shift is controlled within the depth of focus. Clear imaging is achieved in both bands over the entire zoom range. These results demonstrate the effectiveness of the proposed achromatic strategy and provide a practical approach for the design of wide-band achromatic zoom optical systems. Full article

Laser beam combining is essential for achieving high-power and high-radiance output. However, atmospheric turbulence induces independent tip–tilt aberrations across discrete sub-beams in laser array systems, which severely degrades the concentration of far-field energy. Traditional wavefront sensing techniques are primarily designed for the continuous wavefront of a single laser and are not directly applicable to laser array, whereas indirect optimization-based methods often suffer from slow convergence and limited real-time performance. To address these limitations, this study introduces a tip–tilt aberration compensation system for laser array propagation based on cooperative beacons with a shared-aperture transmit–receive configuration. The primary innovation consists of a modified Shack–Hartmann wavefront sensor (SHWFS) tailored to a discrete multi-beam layout, which facilitates the direct, independent, and simultaneous measurement of tip–tilt aberrations for each sub-beam. In conjunction with a segmented deformable mirror (SDM), the architecture can facilitate real-time closed-loop correction with high bandwidth and high precision. Numerical simulations of a 7-, 19-, and 37-beam laser array, together with validation experiments utilizing a 30-beam configuration, demonstrate that the proposed approach effectively suppresses tip–tilt error induced by turbulence. After closed-loop correction, the Strehl ratio (SR) increases above 0.92 ($r_0=5\mathrm{cm}$), while the beam quality factor β reduces below 1.37 ($r_0=5\mathrm{cm}$). Furthermore, the system retains performance stability as the number of sub-beams increases, demonstrating the scalability of the proposed method. In contrast to conventional approaches designed for a continuous wavefront, the proposed method offers a feasible approach for a discrete laser array system, providing robust and scalable tip–tilt correction under varying atmospheric conditions. Full article

Background/Objectives: To evaluate the associations between corneal topographic irregularity, higher-order aberrations (HOAs), and posterior segment structural and microvascular parameters in keratoconus using optical coherence tomography (OCT) and OCT angiography (OCTA). Methods: In this cross-sectional study, 81 eyes with keratoconus and 60 healthy control eyes underwent corneal topography and wavefront analysis, spectral-domain OCT with enhanced depth imaging, and OCTA. Retinal layer thicknesses, choroidal thickness and area metrics, choroidal vascularity index (CVI), and OCTA-derived vascular parameters were analyzed. Associations were assessed using Spearman correlation analysis with false discovery rate (FDR) correction. Results: Compared with controls, keratoconus eyes showed significantly increased corneal curvature, corneal irregularity indices, and HOAs (all p < 0.001). Structural OCT analysis demonstrated preserved inner retinal layers, whereas outer nuclear layer thickness was reduced (p < 0.001) and overall outer retinal layer thickness was increased (p = 0.005). Choroidal thickness and both total and luminal choroidal areas were significantly greater in keratoconus eyes (all p ≤ 0.011), while CVI did not differ between groups (p > 0.05). OCTA revealed reduced superficial capillary plexus vessel density at the whole image and perifoveal regions (all p < 0.001), whereas deep capillary plexus and foveal avascular zone metrics were largely preserved. Correlation analyses identified only weak and inconsistent associations between corneal parameters, HOAs, and posterior segment measurements, none of which remained statistically significant after FDR correction. Conclusions: Despite pronounced anterior segment deformation and optical degradation, posterior segment structural and microvascular alterations in keratoconus are limited and weakly related to corneal disease severity. These findings support a predominantly anterior segment centered pathophysiology of keratoconus and highlight the importance of stringent multiple-comparison control in multimodal imaging studies. Full article

Three-dimensional seed phenotyping requires imaging systems capable of achieving micron-level resolution across a centimeter-level field of view (FOV), a goal constrained by the resolution–FOV trade-off in conventional light field architectures. This paper presents a hardware–software co-optimized framework that integrates a reconfigurable optical system with computational imaging pipelines to address this limitation. At the hardware level, we develop a tunable-focus lens module that enables flexible adjustment of the effective focal length, combined with a custom-designed microlens array (MLA). A mathematical model is established to analyze the interdependencies among FOV, lateral resolution, depth of field (DOF), and system configuration, guiding the design of individual optical components. On the computational side, we propose a hybrid aberration correction strategy: first, a co-calibration of lens and MLA aberrations based on line-feature detection; second, a conditional generative adversarial network (cGAN) with attention-guided residual learning to enhance sub-aperture images, achieving a PSNR of 34.63 dB and an SSIM of 0.9570 on seed datasets. Experimentally, the system achieves a resolution of 6.2 lp/mm at MTF50 over a 2–3 cm FOV, representing a 307% improvement over the initial configuration (1.52 lp/mm). The reconstruction pipeline combines epipolar plane image (EPI) analysis with multi-view consistency constraints to generate dense 3D point clouds at a density of approximately 1.5 × 10⁴ points/cm² while preserving spectral and textural features. Validation on bitter melon and rice seeds demonstrates accurate 3D reconstruction and accurate extraction of morphological parameters across a large area. By integrating optical and computational design, this work establishes a reconfigurable imaging framework that overcomes the resolution–FOV limitations of conventional light field systems. The proposed architecture is also applicable to robotic vision and biomedical imaging. Full article

Designing high-speed wide-angle optics for large-format mirrorless cameras presents a fundamental engineering conflict between the short flange back distance and the requirement for high-resolution aberration correction. To address this challenge, this study proposes a compact 18.5 mm F/2.0 lens system utilizing a modified retrofocus architecture equipped with an internal floating-focus mechanism. The design methodology integrates glass-molded aspherical surfaces to suppress high-order aberrations and employs passive athermalization strategies to maintain stability across a temperature range of −30 °C to +70 °C. Performance was rigorously evaluated using numerical simulations in Zemax OpticStudio, alongside comprehensive Monte Carlo tolerance analysis. Simulation results demonstrate exceptional optical performance, with the Modulation Transfer Function (MTF) exceeding 0.5 at a spatial frequency of 100 lp/mm across the field. Furthermore, focus breathing is restricted to less than 1%, and optical distortion is strictly controlled within 2%. The Monte Carlo tolerance analysis predicts a manufacturing yield exceeding 80% under standard industrial precision levels. Ultimately, this work provides a theoretically sound, athermally stable, and highly manufacturable solution suitable for next-generation high-resolution mirrorless sensors. Full article

Background/Objectives: Ulcerative colitis is a chronic inflammatory bowel disease marked by a disrupted intestinal barrier and consequent aberrant immune responses. Pseudoginsenoside RT2, an ocotillol-type ginsenoside abundant in Panax herbs, represents a potential therapeutic candidate, yet its anti-ulcerative colitis efficacy and pharmacokinetic profile remain unclear. This study aimed to elucidate RT2’s therapeutic potential for ulcerative colitis through a parallel evaluation of pharmacodynamic efficacy and pharmacokinetic properties. Methods: The anti-ulcerative colitis efficacy and in vivo disposition of RT2 were investigated in a trinitrobenzene sulfonic acid-induced rat colitis model. An ultra-performance liquid chromatography–tandem mass spectrometry method was employed to delineate its pharmacokinetic characteristics and quantify its distribution in various tissues following oral administration. Results: Pharmacodynamically, RT2 demonstrated significant efficacy in the UC rat model by repairing the intestinal barrier (by promoting goblet cell regeneration and upregulating tight junction proteins and mucin) and restoring immune homeostasis (by correcting T-helper 17/regulatory T-cell imbalance and reducing pro-inflammatory cytokines while elevating anti-inflammatory cytokines). Pharmacokinetically, RT2 exhibited rapid absorption, slow elimination, and high colonic accumulation, with concentrations in the inflamed colon being significantly higher than those in healthy rats. Furthermore, the biphasic concentration–time profile may account for its prolonged systemic residence time and enhanced local exposure. In summary, through parallel efficacy and pharmacokinetic studies, this work systematically reveals its characteristics as a therapeutic agent that exhibits high colonic accumulation and acts via barrier repair and immunomodulation. Conclusions: These findings provide a theoretical foundation for the development of RT2 as a novel gut-selective drug candidate for UC. Full article

Wide-swath longwave infrared (LWIR) imaging from Low Earth Orbit (LEO) demands fast optics and rectilinear (F-tan) mapping for thermal mapping and multi-frame registration. Achieving an F/1.2 aperture with a 112° diagonal field of view (FOV) and distortion within ±5% is challenging, as mapping constraints and field-dominant off-axis aberrations become strongly coupled at large chief-ray angles. The low-distortion target is not only a geometric specification, but also a practical requirement that reduces peripheral compression, helps maintain edge-detail consistency, and lowers digital de-warping effort in the processing pipeline. While traditional LWIR secondary imaging is predominantly restricted to narrow-field cooled systems for cold-stop constraints, the proposed architecture utilizes a curved intermediate image to effectively decouple mapping formation in the field-dominant front objective from aperture-dominant correction in the rear group. Using chalcogenide glasses, the lens achieves a 5.7 mm effective focal length within a 186.9 mm total track. Analysis over the 8–12 μm band confirms performance approaching the diffraction limit at the 50 lp/mm Nyquist frequency alongside stable geometric fidelity across the full field. Thermal analysis from −40 °C to 80 °C and Monte Carlo tolerance analysis demonstrate stable imaging performance and manufacturing feasibility, confirming the effectiveness of the proposed design approach. Full article