Endoscopic technology plays a crucial role in minimally invasive diagnostic procedures and precision industrial inspections. However, producing a microsized full-color endoscope has been challenging in fabrication and aberration corrections. In this paper, we propose a miniaturized fiber endoscope featuring multiple lens elements with freeform surfaces using two-photon polymerization (TPP) 3 D nanoprinting technology to effectively correct various optical aberrations and have realized good optical performances in full-color imaging. The microlens was integrated onto an imaging fiber tip, achieving a FOV of 60° and a resolution of 7.13 line pairs per mm (lp/mm). In addition, the proposed fiber endoscope is capable of accurately reproducing full-color information while preserving image details across different image types. This research offers an innovative approach to develop high-performance endoscopes and enhance its imaging applications.

Electron cryo-tomography (cryo-ET) enables 3D imaging of complex, radiation-sensitive structures with molecular detail. However, image contrast from the interference of scattered electrons is nonlinear with atomic density and multiple scattering further complicates interpretation. These effects degrade resolution, particularly in conventional reconstruction algorithms, which assume linearity. Particle averaging can reduce such issues but is unsuitable for heterogeneous or dynamic samples ubiquitous in biology, chemistry, and materials sciences. Here, we develop a phase retrieval-based cryo-ET method, PhaseT3M. We experimentally demonstrate its application to an approximately 7 nm Co3O4 nanoparticle on an approximately 30 nm carbon substrate, achieving a maximum resolution of 1.6 Å, surpassing conventional limits using standard cryo-TEM equipment. PhaseT3M uses a multislice model for multiple scattering and Bayesian optimization for alignment and computational aberration correction, with a positivity constraint to recover 'missing wedge' information. Applied directly to biological particles, it enhances reconstruction quality and reduces artifacts, establishing a standard for routine 3D imaging with phase contrast.

Objective.Histotripsy is a non-invasive, non-thermal, and non-ionizing tissue ablation method based on high-amplitude pulses of focused ultrasound that has been approved by the federal Food and Drug Administration for the treatment of liver tumors. However, histotripsy currently cannot treat all locations in the liver due to attenuation of the pressure amplitude at the focus by sound-blocking ribs and air pockets and by phase aberration, or de-focusing of the ultrasound pulses by heterogeneous bodily tissues. Previous work suggests that correcting for phase aberration could increase the focal pressure to expand the treatment envelope (the treatable region) for histotripsy in the liver. The objective of this study was to investigate the effect of aberration correction on the treatment envelope.Approach. Acoustic propagation was simulated in the human body using a linear model (k-Wave) for a histotripsy phased array of similar dimensions to the current Histosonics Edison® clinical device and anatomical data from 10 subjects of varying body size.Main results. We find that aberration correction increases the focal pressure throughout the liver to substantially expand the treatment envelope (from 67% to 81% of the liver volume, on average, by linear estimations).Significance. The study suggests that aberration correction could help enable non-invasive, non-thermal histotripsy treatments for a broader patient population.

High-Resolution EELS in an aberration-corrected LEEM: Design of electrostatic transfer lenses for hemispherical filters.

Quantitative and three-dimensional observations by electron holography.

The desire for cameras with smaller form factors has recently led to a push for exploring computational imaging systems with reduced optical complexity such as a smaller number of lens elements. Unfortunately such simplified optical systems usually suffer from severe aberrations, especially in off-axis regions, which can be difficult to correct purely in software. In this paper we introduce Fovea Stacking, a new type of imaging system that utilizes an emerging dynamic optical component called the deformable phase plate (DPP) for localized aberration correction anywhere on the image sensor. By optimizing DPP deformations through a differentiable optical model, off-axis aberrations are corrected locally, producing a foveated image with enhanced sharpness at the fixation point - analogous to the eye's fovea. Stacking multiple such foveated images, each with a different fixation point, yields a composite image free from aberrations. To efficiently cover the entire field of view, we propose joint optimization of DPP deformations under imaging budget constraints. Due to the DPP device's non-linear behavior, we introduce a neural network-based control model for improved agreement between simulation and hardware performance. We further demonstrated that for extended depth-of-field imaging, Fovea Stacking outperforms traditional focus stacking in image quality. By integrating object detection or eye-tracking, the system can dynamically adjust the lens to track the object of interest-enabling real-time foveated video suitable for downstream applications such as surveillance or foveated virtual reality displays.

ABSTRACT Long‐wave infrared (LWIR) metalenses, capable of precise wavefront modulation through subwavelength meta‐atoms, represent a transformative advancement in infrared optics, offering a compact alternative to conventional refractive elements. This work systematically examines the fundamental principles, typical designs, and fabrication challenges of LWIR metalenses, with an emphasis on different phase modulation strategies, presenting their distinct advantages and limitations. Recent breakthroughs in aberration correction, wide‐field imaging, and polarization‐sensitive functionalities are critically reviewed, alongside computational optimization approaches such as deep learning and topology algorithms. Fabrication techniques, including advanced lithography and etching, are evaluated for their scalability and precision in realizing high‐performance metasurfaces. Persistent challenges in efficiency, thermal stability, and large‐scale manufacturing underscore the need for novel materials, refined nanofabrication methods, and integrated design frameworks. By addressing these barriers, LWIR metalenses hold potential to revolutionize applications in thermal imaging, defense systems, and biomedical sensing, paving the way for next‐generation infrared technologies.

Author Correction: Light-based electron aberration corrector

ABSTRACT Optically intracellular manipulation and sensing, both in vivo and in vitro, face fundamental challenges due to spatially varying aberrations arising from refractive index heterogeneity and dynamic organelle motion. Achieving high‐speed laser field optimization to correct aberrations is essential but remains challenging. Here, we develop a particle swarm optimized optical tweezers (PSOOT) employing a multimodal synergistic strategy to enhance both the speed and performance of trapping beam optimization. Leveraging fluorescence feedback to dynamically and simultaneously modulate Zernike aberration modes enables faster convergence to the target intensity levels through multimodal coordination. In numerical simulation, this strategy can find the potential solutions at a speed more than four times faster than the traditional scanning method. Experimentally, PSOOT achieves an order‐of‐magnitude enhancement in trap stiffness for 1 µm spheres, increasing k x from 0.30 to 3.36 pN/µm/mW and for 110 nm particles in aqueous solution, from 0.11 to 0.34 pN/µm/mW, approaching the theoretical limit for such trapped objects. The optimized optical trap enables the stable trapping and optical‐driven manipulation of a single lipid droplet in living HeLa cells. Furthermore, the spatial intracellular heterogeneity of aberrations is quantitatively investigated. The methodology establishes a new paradigm for closed‐loop optical tweezers in biological environments, which may advance the mechanobiology studies, such as intracellular targeted delivery and cellular surgery.

HighlightsWhat are the main findings?A Power-Corrector (PC) group positioned between the objective and intermediate image enables unified optimization of the optical system, achieving superior performance with an 86° apparent field of view while maintaining compact dimensions.The PC-based design demonstrates significantly improved optical quality with ~5% distortion compared to ~24% in conventional designs and achieves 42.5% length reduction and 44.9% diameter reduction compared to Nagler-based systems with identical specifications.What is the implication of the main finding?The PC group enables practical wide-field optical devices with 1.6× larger FOV diameter (~2.56× viewing area) than conventional monoculars of identical physical dimensions, enhancing scene scanning efficiency for applications requiring stationary observation with eye movement scanning.This technology enables compact, high-performance monoculars, binoculars, and spotting scopes suitable for bird watching, hunting, sports, military, and astronomical applications, addressing the traditional trade-off between field of view and system compactness.A new concept for designing a visual magnification system is introduced. In this concept, apart from the conventional objective and the eyepiece group lenses in the system, an additional Power-Corrector (PC) group of lenses is introduced in the optical design. The Power-Corrector group is located between the objective and the intermediate image and allows an additional degree of freedom to the optical design. This enables improving the system’s performance such as the field of view (FOV) while eliminating the system’s aberrations or reducing them to an insignificant level. Incorporating the PC group achieves this by correcting aberrations that typically limit the performance of conventional eyepiece designs, allowing a wider acceptance angle for incoming light. Recent advances in wide field of view optical systems and compact optical design methodologies have highlighted the ongoing challenges in balancing field of view expansion with aberration control. In this configuration, the PC group unifies the units, the eyepiece and the objective groups, integrates their functionality to one coherent system such that the input focal length of the system is defined jointly by the focal lengths of the objective and the PC while the aberrations are corrected jointly by the PC and the eyepiece. Thus, while the system’s magnification is the ratio of the input focal length to the eyepiece focal length, the PC enables global optimization such that the PC and the eyepiece together have a combined aberration that is less than the characteristic aberration of the eyepiece. This integrated optimization enhances the FOV. Additionally, it maintains image quality, making the system more effective than traditional designs. Contemporary research in freeform optical surface design and optimization techniques demonstrates the growing importance of advanced aberration correction methods in modern optical systems. Using this concept, a compact imaging system with a wider FOV relative to customary designs with the same magnifications, was designed and manufactured.

Light-sheet microscopy is ideal for imaging large and cleared tissues, but achieving a high isotropic resolution for a centimeter-sized sample is limited by slow and often aberrated, axially scanned light sheets. Here, we introduce a compact, high-speed light-sheet fluorescence microscope achieving 850 nm isotropic resolution across cleared samples up to 1 cm³ and refractive indices ranging from 1.33 to 1.56. Using off-the-shelf optics, we combine an air objective and a meniscus lens with an axially swept light sheet to achieve diffraction-limited resolution and aberration correction. The effective field of view is increased by twofold by correcting the field curvature of the light sheet using a concave mirror in the remote focusing unit. Adapting the light sheet's motion with a closed-loop feedback enhances the imaging speed by tenfold, reaching 100 frames per second while maintaining resolution and field of view. We benchmark the system performance across scales, from subcellular structure up to centimeter scale, using various clearing methods.

Objective.Transcranial focused ultrasound therapies depend on accurately focusing the ultrasound beam through the skull. Simulated phase aberration correction with properties derived from computed tomography (CT) can partially restore the focus. However, the typical clinical CT resolution (0.5 mm isotropic) cannot resolve the bone microstructure, introducing uncertainty in the velocity relationship to CT Hounsfield units (HUs), which reduces focusing precision.Approach.To demonstrate this, we simulated through-transmission measurements through skull-mimicking digital phantoms consisting of cortical bone and marrow with porosities ranging from 0% to 80%. The phantoms comprised spherical marrow pores (0.1-0.6 mm diameter) randomly placed into a cortical background, forming fine-to-coarse microstructures. Using k-Wave, we simulated pulsed and continuous planar sources at four center frequencies (250 kHz, 500 kHz, 750 kHz, 1 MHz). Group and phase velocities are reported for each pore diameter and porosity. The steady-state phase is reported through representative phantoms.Main results.The velocity varies with pore diameter and porosity, with smaller pores yielding faster velocities than larger pores at the same porosity. At 25% porosity and 500 kHz, group velocity ranges from 3147 to 2211 m s-1and phase velocity from 3168 to 2345 m s-1across 0.1-0.6 mm pore diameters. The steady state phase depends on the pore diameter and frequency, with the variation across the measurement plane broadening as both increase, indicating dependence on the microstructure's pore distribution.Significance.The results indicate that the velocity relationship to CT HUs is ill-determined due to the unresolved microstructure. The variation in group velocity impacts pulsed sources, such as those used for histotripsy, while variation in phase velocity affects quasi-continuous sources, including those used for neuromodulation and thermal ablation. Our results emphasize the need to account for the skull microstructure for safer and more effective transcranial focusing.

To mitigate the alignment challenges of reflective telephoto systems and the extended optical paths of refractive systems, this paper proposes a mini employing a single cemented negative meniscus lens and outlines its design methodology. A theoretical model is developed based on Snell’s law, which constrains the solution space; a fitness function is then constructed based on key design metrics, and the particle swarm optimization algorithm is employed to simultaneously optimize the lens parameters and the local reflective coating area, resulting in a viable initial configuration. Subsequently, an aspheric machined surface is introduced on the lens to correct residual aberrations. An alternative design consisting of two spherical lenses is also presented. The results demonstrate that the system achieves an 8° full field of view, an f-number of 4.5, a modulation transfer function exceeding 0.2 at 125 lp/mm, and near-diffraction-limited imaging in the visible band; tolerance analysis confirms its high robustness to manufacturing and alignment errors. The proposed design is compact, straightforward to manufacture, and cost-effective, providing a viable approach for miniaturized, high-performance telephoto imaging systems.

A high-flux, high-resolution Offner imaging spectrometer with a compact configuration is proposed and demonstrated. By introducing a custom-designed lens group between the entrance slit and the primary concave mirror, the effective slit is optically transformed into a virtual slit with extended divergence and path length. This design fundamentally alleviates astigmatism and enables a larger numerical aperture (NA = 0.3), while preserving the intrinsic aberration-free benefits of the Offner configuration. Theoretical modeling and optical analysis were conducted to derive aplanatic conditions and optimize focal power distribution. A three-lens assembly, including a toroidal surface, was employed to decouple meridional and sagittal focal lengths and correct residual aberrations. The optimized system covers the 400–1000 nm spectral range with a measured spectral resolution of 1.35 nm and maintains an MTF>0.7 at 28 lp/mm across the full field of view. Compared to a conventional Offner spectrometer of equal resolution, the proposed design improves optical throughput by a factor of 2.25 and reduces system volume by 14.5%. Laboratory calibration using a mercury–argon lamp confirmed its high-resolution capabilities, and field experiments demonstrated excellent spectral and spatial imaging performance. The improved Offner spectrometer offers a compact, aberration-free, and high-resolution solution for applications requiring high-precision spectral imaging.

An electrostatic aberration corrector for improved Low-Voltage SEM imaging.

Cryogen-free low-temperature photoemission electron microscopy for high-resolution nondestructive imaging of electronic phases.

Improving the low-dose performance of aberration correction in single sideband ptychography.

Accessible and thorough magnetic field mapping of TEMs using a commercial Hall-sensor and TEM automation for in situ magnetic experiments.

Transcranial ultrasound localization microscopy (t-ULM) faces significant challenges for broader clinical and research applications, particularly in addressing image quality degradation caused by the skull. Research on nonhuman primate (NHP) models, with their human-like cranial characteristics, offers crucial insights for technical innovations and neuroscience applications of t-ULM. In this study, we developed a systematic pipeline for t-ULM of NHP, incorporating low-frequency diverging wave emission, phase aberration correction, and microbubble (MB) detection equalization. We also explored the contrast agent strategies and imaging plane selection. We achieved an optimal spatial resolution of 93 $\mu $ m in the coronal section and 105 $\mu $ m in the sagittal section at an emission frequency of 2.23 MHz, while both maintaining 5-8-cm penetration depth and 6-cm lateral field of view. We also obtained the hemodynamic mapping with a wide dynamic range up to 40 cm/s at a 1000-Hz compounded frame rate. This work validates the feasibility of t-ULM in the NHP and provides important tools and references for further neuroscience applications of t-ULM.

We provide detailed experimental guidelines for implementing digital holography in the context of high-sensitivity interferometric scattering (iSCAT)-based nanosizing applications. Our approach relies on interferometry via the highly versatile off-axis implementation of digital holography, which offers key advantages over more traditional strategies. After a brief theoretical discussion of off-axis holography and its differences and similarities with iSCAT, typical experimental implementations and digital data-processing steps are presented. Key experimental parameters and strategies to achieve optimal performance are also highlighted. Following these experimental aspects, we focus on digital postprocessing routines that enable digital refocusing and 3D particle tracking as well as pupil function aberration correction. We then conclude with a few examples highlighting the broad applicability of digital holography for nanosizing and particle characterization applications, as well as an outlook for future applications.