Search Results (506)

High-resolution long-wave infrared imaging is critical for lunar mineralogy. However, it must balance a large FOV, a small F-number, chromatic aberration correction, optical efficiency, and system compactness. We introduce a push-broom multispectral imager employing a collaborative integrated filter array and an off-axis two-mirror Gregorian telescope. The system, utilizing an uncooled Vanadium Oxide detector, has an F-number of 1.0, an IFOV of 0.04943 mrad, and a 2.90° × 2.83° FOV that covers eight bands ranging between 7.38 and 14.3 μm. Optical simulation confirms that the modulation transfer function exceeds 0.25 at the Nyquist frequency of 42 lp/mm, with a maximum RMS spot radius of less than 12 μm. The system has remarkable versatility within an operating temperature range of 0 °C to 40 °C. Thermal background radiation analysis, stray light analysis, and detection sensitivity were conducted, which indicated that the system has good compliance with indicators and engineering feasibility. This high-throughput optical design meets the rigorous criteria for lunar remote sensing and provides a reliable device for site evaluation in future manned lunar missions. Full article

For Autonomous Vehicles (AVs), recognizing traffic lights and signs is critical for safety because perception errors directly affect navigation decisions. Real-world disturbances such as glare, rain, dirt, and graffiti, as well as digital adversarial attacks, can lead to dangerous misclassifications. Current research lacks (i) temporal continuity (stable detection across consecutive frames to prevent flickering misclassifications), (ii) multi-field-of-view (FoV) sensing, and (iii) integrated defenses against both digital and natural degradation. This paper presents two principal contributions: (1) a three-layer defense framework integrating feature squeezing, inference-time temperature scaling (softmax $\tau$ = 3 without distillation training), and entropy-based anomaly detection with sequence-level temporal voting; (2) a 500 sequence dual-FoV benchmark (30k base frames, 150k with perturbations) from aiMotive, Waymo, Udacity, and Texas sources across four operational design domains. The unified defense stack achieves 79.8% mAP on a 100-sequence test set (6k base frames, 30k with perturbations), reducing attack success rate from 37.4% to 18.2% (51% reduction) and high-risk misclassifications by 32%. Cross-FoV validation and temporal voting enhance stability under lighting changes (+3.5% mAP) and occlusions (+2.7% mAP). Defense improvements (+9.5–9.6% mAP) remain consistent across native 3D (aiMotive, Waymo) and projected 2D (Udacity, Texas) annotations. Preliminary recapture experiments (n = 15 scenarios) show 2.5% synthetic–physical ASR gap (p = 0.18), though larger validation is needed. Code, models, and dataset reconstruction tools are publicly available. Full article

Background/Objectives: Cone beam computed tomography (CBCT) is vital in endodontics but suffers from beam-hardening artifacts caused by metallic restorations, which can obscure diagnostic details. This study evaluated a novel patient positioning protocol—a controlled head tilt—designed to mitigate these artifacts by moving contralateral metallic structures outside the primary X-ray path in small field of view (FoV) CBCTs. Methods: Using a skull phantom with metallic restorations CBCT scans were acquired in three positions: standard alignment, a 12° tilt toward the region of interest (ROI), and a 12° tilt to the opposite side. Fifty experienced dentists, blinded to the protocol, subjectively compared image quality and artifact severity between the tilted and reference images. Results: The tilt away from the ROI was rated as providing better image quality significantly more often than the tilt towards the side of the ROI (442 of 585 non-tied comparisons; p < 0.001). A complementary rater-clustered GEE analysis adjusted for slide confirmed higher odds of “better” ratings under head tilt away from the ROI for image quality (OR = 4.16, 95% CI 3.12–5.56) and artefacts (OR = 2.87, 95% CI 1.93–4.26). An individual head tilt significantly improves subjective small-FoV CBCT image quality, most evidently in the longitudinal plane, by reducing artifact interference from contralateral metals, and should be considered a practical strategy for clinical use, and may serve as a practical chairside strategy, pending clinical validation. Full article

To address the critical challenges of minimizing optical thickness and correcting chromatic aberrations in optically transparent head-mounted displays (HMDs), we propose a folded hybrid design incorporating freeform prisms and a discrete multi-wavelength achromatic metalens. Our approach integrates advanced optical engineering techniques to achieve optimal performance while maintaining compactness. The system leverages a phase-optimized SiNx/SiO₂ metalens combined with ray-tracing-based system optimization, enabling the development of a compact 12 mm thickness OST-HMD featuring an 8 mm exit pupil and a 39° virtual field of view (FOV). Through simulations, we demonstrate that this configuration achieves impressive modulation transfer function (MTF) values exceeding 0.7 at 50 lp/mm for see-through viewing and maintaining MTFs above 0.3 at 30 lp/mm for virtual imaging across wavebands. Simulation results highlight an improvement both in the miniaturization of the HMD while maintaining high resolution and in effective correction of chromatic aberrations, offering a robust solution for lightweight, high-performance AR display systems. This work represents an advancement in optically transparent display technology by providing an optimized design framework that balances compactness with visual fidelity. Full article

Lensless on-chip microscopy enables high-throughput, wide-FOV imaging; however, the Bayer color filter array (CFA) in standard color sensors spatially multiplexes spectral channels, introducing sub-sampling and spectral crosstalk that degrade phase retrieval. We propose a Wirtinger Poly-Gradient Solver (WPGS) for quantitative phase reconstruction with Bayer-filtered color sensors under sequential Red–Green–Blue Light-Emitting Diode (RGB-LED) illumination. The method combines Transport of Intensity Equation (TIE)-based initialization with polychromatic Wirtinger optimization to suppress CFA-induced artifacts and enable pixel super-resolution (PSR). Experiments resolve a $2.76 \mu \mathrm{m}$ linewidth using a $1.85 \mu \mathrm{m}$ pixel-pitch sensor, exceeding the nominal Nyquist limit imposed by pixel sampling. We further demonstrate label-free imaging of HeLa cells and unstained tissue sections, supporting high-throughput digital pathology and offering potential for longitudinal biological observation. Full article

Eye tracking in virtual reality (VR) head-mounted displays poses substantial engineering challenges, particularly under immersive display configurations with large fields of view (FOV), where optical layout, illumination, and image acquisition impose nontrivial system constraints. To address these design constraints, we present an integrated near-eye eye-tracking prototype tailored for immersive VR headsets, combining customized hardware components and a real-time software pipeline. The proposed system integrates optimized near-eye illumination and image acquisition with a pupil detection module and a deep learning-based gaze-vector estimation model, forming a real-time software pipeline for stable end-to-end gaze mapping under fixed calibration conditions. Under identical system settings, calibration procedures, and gaze-point mapping conditions, we evaluate the proposed gaze-vector estimation model through a controlled model-level ablation. The attention-enhanced model achieves an average angular deviation of 1.15°, corresponding to a 61.4% relative reduction compared with a baseline ResNet-152 model without attention. To demonstrate the usability of the system outputs at the application level, we further implement a real-time visualization example that integrates pupil diameter, gaze vectors, and blink events to depict the temporal evolution of eye-movement signals. This work provides a cost-effective and reproducible engineering reference for near-eye eye-movement acquisition and visualization in immersive VR settings and serves as a technical foundation for subsequent interaction design or behavioral analysis studies. Full article

Off-axis reflective telescopes are prone to component misalignment due to external environmental factors and mechanical vibrations. This misalignment introduces low-order aberrations, which severely degrade imaging quality. Thus, active misalignment correction is crucial for maintaining the imaging performance of off-axis reflective telescopes. Current computer-aided alignment technologies for optical systems mostly rely on wavefront sensors to acquire aberrations at multiple fixed fields of view (FOVs) or even the full FOV. This significantly increases system complexity and hinders practical engineering applications. To address this issue, this study first conducts sensitivity analysis of misaligned degrees of freedom (DOFs) using a mode truncation algorithm based on singular value decomposition (SVD). A compensation strategy is proposed to avoid the aberration coupling effect. Furthermore, two novel misalignment aberration compensation methods for off-axis reflective telescopes are presented. These methods require only a single focal spot image and eliminate the need for aberration detection and iterative calculations. One method directly solves component misalignment errors using a convolutional neural network (CNN) based on the system’s point spread function (PSF). To further improve compensation performance, an improved method fusing spot images and Zernike coefficients is proposed. In practical misalignment correction, both methods input a single acquired focal spot image into a well-trained model to obtain the misalignment compensation amount. Simulation experiments demonstrate that the improved method, which uses Zernike polynomial coefficients as an intermediate feature bridge, effectively establishes the mapping relationship between spot images and misalignment amounts. It achieves higher solution accuracy and better aberration compensation effect compared to the direct CNN method. This verifies the necessity of extracting Zernike polynomial coefficient features from spot images. Comparative experiments with the traditional sensitivity matrix method show that the two proposed methods outperform the sensitivity matrix method in aberration compensation accuracy over a large misalignment range. Comprehensive simulation results confirm the feasibility and effectiveness of the proposed methods. They overcome the limitations of existing methods, such as complex structure, high cost, and low efficiency, to a certain extent. Full article

Fluorescence emission-guided blood flow and lymph node location detection are important observation methods in cancer removal surgery, where near-infrared LED illumination is used to induce fluorescence emission. However, conventional LED light sources have narrow beam widths, resulting in a limited excitation area and a restricted field of view (FOV). In this study, we propose a balanced optical illumination module that combines a beam-focusing condenser lens and a beam-diffusing lens to expand the beam width while efficiently redistributing optical energy. When only the LED was used, the beam diameter and central irradiance were 4.0 cm and 1.43 mW/cm², respectively. With the condenser lens, the beam diameter remained nearly unchanged (3.98 cm), while the central irradiance decreased to 0.91 mW/cm². When the condenser was combined with the proposed diffuser structure, the beam diameter increased to 14.1 cm, corresponding to an approximately 3.5-fold expansion, while the central irradiance was measured at 0.72 mW/cm², reflecting the redistribution of optical energy from an initially Gaussian-like irradiance distribution into a wider and more uniform illumination area. This irradiance level exceeds the minimum threshold of 0.6 mW/cm² required to induce fluorescence emission, as defined for the experimental working distance of 30 cm and LED power of 200 mW. By integrating the irradiance distributions of both the bare LED and the proposed structure over their respective illuminated surfaces, the measured total power is physically consistent with energy conservation, showing an expected transmission loss of 18.8% due to optical absorption and scattering. These results demonstrate that the proposed beam diffusion-concentration approach provides an effective and practical solution for wide-field fluorescence-guided lesion observation during cancer removal surgery. Full article

Multi-channel common-aperture optical systems, which excel at simultaneous multi-spectral information acquisition, are widely used for image fusion. However, complex systems for long-distance multi-band detection suffer from difficulties in assembly and adjustment and light vignetting. To resolve this, the paper proposes a modular design method that splits the optical path into independent modules: the common-aperture optical path adopts an off-axis reflective beam-shrinking structure to extend the focal length and ensure 100% light input, compared with coaxial multi-channel common-aperture systems. The relay optical path of each spectral channel uses a continuous zoom design for smooth detection–recognition switching. Based on the method, a three-channel common-aperture system is developed integrating visible light (VIS), short-wave infrared (SWIR), and mid-wave infrared (MWIR). The modulation transfer function (MTF) and wavefront distribution of the common-aperture optical path approach the diffraction limit. After integration with the relay optical paths, the system, without global optimization, can achieve the following performance: the root mean square (RMS) across the full field of view (FOV) at different focal lengths for each channel is smaller than the detector pixel size (3.45 μm for VIS, 15 μm for SWIR/MWIR); the MTF exceeds 0.2 at the cutoff frequency. Subsequently, the results of the tolerance analysis verify the feasibility of the design for each module and the advantage of the modular layout in the assembly and adjustment of the system. Finally, the paper discusses the influence of parallel plates on the wavefront distortion of the system and proposes optimization thinking using freeform surfaces. The design results of the study validate the feasibility of the modular layout in simplifying the design and assembly of multi-channel common-aperture optical systems. Full article

Insects rely on their olfactory systems for host finding, mate choice, and oviposition. These odor-guided behaviors are mediated by the peripheral chemosensory system. The solanaceous pests Phthorimaea operculella and Phthorimaea absoluta cause severe damage to solanaceous crops worldwide. In this study, we aimed to elucidate the olfactory molecular mechanisms of these two pests. We first screened and identified odorant-binding proteins (OBPs), chemosensory proteins (CSPs), and sensory neuron membrane proteins (SNMPs) from the genomes of P. operculella and P. absoluta. We then used RNA sequencing to characterize the tissue expression profiles of OBPs, CSPs, and SNMPs in P. operculella across developmental stages and adult chemosensory organs. From P. operculella, 47 OBPs, 26 CSPs, and 2 SNMPs were identified, and from P. absoluta, 39 OBPs, 24 CSPs, and 2 SNMPs were identified. RNA-seq-based expression profiling in P. operculella was used to resolve sex-biased deployment in antennae: DESeq2 analysis (|log₂FC| > 1, FDR < 0.05) identified 24 OBPs and four CSPs with significant sexual dimorphism, with 14 OBPs and four CSPs upregulated in female antennae (FAn) and 10 OBPs and one CSP, together with SNMP2, upregulated in male antennae (MAn). In reproductive tissues (FOv vs. MGe), three OBPs and one CSP were enriched in the female ovipositor (FOv), whereas six OBPs and five CSPs were enriched in male genitalia (MGe), and no SNMPs met the differential-expression threshold. These candidate genes provide molecular entry points for functional studies and for developing behavior-based, environmentally compatible management strategies for P. operculella and P. absoluta. Full article

This work presents integrated flux and velocity channel maps of the planetary nebula Abell 30 (A30) inner knot system. The observations were taken with the INTEGRAL spectrograph at the William Herschel Telescope (WHT), La Palma, Spain. Our IFU data cube has a field of view (FoV) of 12.3″× 16″ that partially covers knots J1 and J2, and completely covers knots J3 and J4 in the system. Optical Recombination Lines (ORLs) of C II, He I, He II, N III, O II and Collisionally Excited Lines (CELs) of [Ar IV], [Ar V], [N II], [Ne III], [Ne IV], and [O III] were detected. Our integrated flux maps visualise the ionisation structure and the chemical inhomogeneity in the system previously reported by other groups. We find that ORLs are concentrated in the polar region (J1, J3), whereas the equatorial knots (J2, J4) are dominated by CELs. The flux ratio map of the diagnostic [O III $\lambda$ 5007/4363 Å] lines reveals the electron temperature distribution, which shows cold cores of 15,000 K in knots J3 and J4 surrounded by a hot outer layer of above 20,000 K. Our channel maps show positive and negative velocity excursions from the systemic value among the ions. Several ions show variation in their velocity structures from their lower-energy-level counterparts, including [Ar IV] and [Ar V], [Ne III] and [Ne IV], and He I and He II. New recurrent velocity structures are identified in the low-density regions where the ions move much faster compared to their surrounding environments. The velocity dispersion measurements highlight extreme turbulence in some of the ions (${\sigma }_{{\mathrm{v}}_{\mathrm{rad}}}\approx 140$ km/s), consistent with supersonic/hypersonic motion driven by shocks. The forbidden line species [N II] exhibits lower turbulence (${\sigma }_{{\mathrm{v}}_{\mathrm{rad}}}\approx$ 50–60 km/s), tracing denser, less-turbulent gases. Based on our data, we conclude that both the ionisation and kinematic studies hint at shock heating and multiple ejection history in the evolutionary pathway of A30. Full article

A target state estimation method based on multiple quadrotors is proposed for unknown maneuvering targets, and a distributed formation control method Image-Based Visual Servoing (IBVS) is also proposed to achieve encirclement tracking of unknown maneuvering targets. In the tracking control, collision avoidance constraints for nodes within the formation are also introduced, and based on the shared position information within the formation, the positions of other nodes within the Field of View (FOV) of each node are predicted for detecting unknown targets. Firstly, an Interacting Multiple Model (IMM) was designed based on multiple motion modes to estimate the position and velocity of the target. A virtual camera coordinate system containing translational and yaw rotations was established between the formation and the target based on the estimated values. Then, a distributed control method based on IBVS was further designed by combining image deviation. At the same time, a safe distance between nodes within the formation was introduced, and collision avoidance constraints of the Control Barrier Function (CBF) were designed. Finally, the position of the formation nodes within the FOV was predicted. The simulation results demonstrate that, utilizing the proposed estimation method, the estimation accuracy for target velocity improves by 26.5% in terms of Root Mean Square Error (RMSE) compared to existing methods. Furthermore, the proposed control method enables quadrotor formations to successfully achieve encirclement tracking of unknown maneuvering targets, significantly reducing tracking errors in comparison to conventional approaches. Full article

Quantitative evaluations in 3D images acquired via Cone-Beam Computed Tomography (CBCT) are limited by the scatter abundance and cone-beam artifacts. This work investigates benefits in using an innovative scanning geometry in CBCT (eCT), which replaces each projection of the conventional scanning protocol with a series of collimated projections (Np) acquired over an oscillating trajectory, realized either with an oscillating source or a multi-spot array. In silico tests employed a cylindrical water phantom embodying inserts of four biological materials. 1 mm-thick bone slabs were sandwiched between 9 mm water slabs to evaluate the image conspicuity. eCT improved the Hounsfield Unit (HU) accuracy, with a direct relation with Np. eCT with Np = 10 reduced the bias of the estimated HU more than two times when compared to CBCT. Increasing the Np presented a large impact on the image conspicuity for portions of the field of view (FOV) distant from the central axial plane, with the signal-to-noise ratio between water and bone slabs increasing by a factor of 18 for Np = 10 compared to CBCT. The proposed eCT configuration is expected to be adopted in applications without strict demand for scanning time and projection number, such as dentomaxillofacial and intrasurgical imaging, imaging of the extremities, and image-guided radiotherapy. Full article

This work presents a biomimetic curved compound-eye imaging system (BCCEIS) engineered for extended-range depth mapping. The system is designed to emulate an apposition-type compound eye and comprises three key components: a hemispherical array of lenslets forming a curved multi-aperture imaging surface, an optical relay subsystem that transforms the curved focal plane into a flat image plane compatible with a commercial CMOS sensor, and a high-resolution CMOS detector. Comprehensive optical analysis confirms effective aberration correction, with the root-mean-square (RMS) spot radii across the field of view (FOV) remaining smaller than the radius of the Airy disk. The fabricated prototype achieves an angular resolution of 2.5 mrad within an ultra-wide 97.4° FOV. Furthermore, the system demonstrates accurate depth reconstruction within the entire FOV at distances up to approximately 2 m, exhibiting errors below 2%. Owing to its compact form, wide FOV, and robust depth-sensing performance, the BCCEIS shows strong potential as a payload for unmanned aerial vehicles in applications such as security surveillance and obstacle avoidance. Full article

Large field-of-view (FOV) infrared imaging, widely utilized in applications including target detection and remote sensing, generates massive datasets that pose significant challenges for transmission and storage. To address this issue, we propose an efficient lossless compression method for large FOV infrared video. Our approach employs a hybrid prediction strategy within the transform domain. The video frames are first decomposed into low- and high-frequency components via the discrete wavelet transform. For the low-frequency subbands, an improved low-latency Multi-view High-Efficiency Video Coding (MV-HEVC) encoder is adopted, where the background reference frames are treated as one view to enable more accurate inter-frame prediction. For high-frequency components, pixel-wise clustered edge prediction is applied. Furthermore, the prediction residuals are reduced by optimal direction prediction, according to the principle of minimizing residual energy. Experimental results demonstrate that our method significantly outperforms mainstream video compression techniques. While maintaining compression performance comparable to MV-HEVC, the proposed method exhibits a 19.3-fold improvement in computational efficiency. Full article