Airy-beam holographic sonogenetics for advancing neuromodulation precision and flexibility.

Advancing our understanding of brain function and developing treatments for neurological diseases hinge on the ability to modulate neuronal groups in specific brain areas without invasive techniques. Here, we introduce Airy-beam holographic sonogenetics (AhSonogenetics) as an implant-free, cell type-specific, spatially precise, and flexible neuromodulation approach in freely moving mice. AhSonogenetics utilizes wearable ultrasound devices manufactured using 3D-printed Airy-beam holographic metasurfaces. These devices are designed to manipulate neurons genetically engineered to express ultrasound-sensitive ion channels, enabling precise modulation of specific neuronal populations. By dynamically steering the focus of Airy beams through ultrasound frequency tuning, AhSonogenetics is capable of modulating neuronal populations within specific subregions of the striatum. One notable feature of AhSonogenetics is its ability to flexibly stimulate either the left or right striatum in a single mouse. This flexibility is achieved by simply switching the acoustic metasurface in the wearable ultrasound device, eliminating the need for multiple implants or interventions. AhSonogentocs also integrates seamlessly with in vivo calcium recording via fiber photometry, showcasing its compatibility with optical modalities without cross talk. Moreover, AhSonogenetics can generate double foci for bilateral stimulation and alleviate motor deficits in Parkinson's disease mice. This advancement is significant since many neurological disorders, including Parkinson's disease, involve dysfunction in multiple brain regions. By enabling precise and flexible cell type-specific neuromodulation without invasive procedures, AhSonogenetics provides a powerful tool for investigating intact neural circuits and offers promising interventions for neurological disorders.

Spin-Selective Angular Dispersion Control in Dielectric Metasurfaces for Multichannel Meta-Holographic Displays.

Angle-dependent next-generation displays have potential applications in 3D stereoscopic and head-mounted displays, image combiners, and encryption for augmented reality (AR) and security. Metasurfaces enable such exceptional functionalities with groundbreaking achievements in efficient displays over the past decades. However, limitations in angular dispersion control make them unfit for numerous nanophotonic applications. Here, we propose a spin-selective angle-dependent all-dielectric metasurface with a unique design strategy to manifest distinct phase information at different incident angles of light. As a proof of concept, the phase masks of two images are encoded into the metasurface and projected at the desired focal plane under different angles of left circularly polarized (LCP) light. Specifically, the proposed multifunctional metasurface generates two distinct holographic images under LCP illumination at angles of +35 and -35°. The presented holographic displays may provide a feasible route toward multifunctional meta-devices for potential AR displays, encrypted imaging, and information storage applications.

Asymmetric Full-Color Vectorial Meta-holograms Empowered by Pairs of Exceptional Points.

Holography holds tremendous promise in applications such as immersive virtual reality and optical communications. With the emergence of optical metasurfaces, planar optical components that have the remarkable ability to precisely manipulate the amplitude, phase, and polarization of light on the subwavelength scale have expanded the potential applications of holography. However, the realization of metasurface-based full-color vectorial holography remains particularly challenging. Here, we report a general approach utilizing a modified Gerchberg-Saxton algorithm to achieve spatially aligned full-color display and incorporating wavelength information with an image compensation strategy. We combine the Pancharatnam-Berry phase and pairs of exceptional points to address the issue of redundant twin images that generally appear for the two orthogonal circular polarizations and to enable full polarization control of the vectorial field. Our results enable the realization of an asymmetric full-color vectorial meta-hologram, paving the way for the development of full-color display, complex beam generation, and secure data storage applications.

Micro-Acoustic Holograms for Detachable Microfluidic Devices.

Acoustic microfluidic devices have advantages for diagnostic applications, therapeutic solutions, and fundamental research due to their contactless operation, simple design, and biocompatibility. However, most acoustofluidic approaches are limited to forming simple and fixed acoustic patterns, or have limited resolution. In this study,a detachable microfluidic device is demonstrated employing miniature acoustic holograms to create reconfigurable, flexible, and high-resolution acoustic fields in microfluidic channels, where the introduction of a solid coupling layer makes these holograms easy to fabricate and integrate. The application of this method to generate flexible acoustic fields, including shapes, characters, and arbitrarily rotated patterns, within microfluidic channels, is demonstrated.

Enlarged Eye-Box Accommodation-Capable Augmented Reality with Hologram Replicas.

Augmented reality (AR) technology has been widely applied across a variety of fields, with head-up displays (HUDs) being one of its prominent uses, offering immersive three-dimensional (3D) experiences and interaction with digital content and the real world. AR-HUDs face challenges such as limited field of view (FOV), small eye-box, bulky form factor, and absence of accommodation cue, often compromising trade-offs between these factors. Recently, optical waveguide based on pupil replication process has attracted increasing attention as an optical element for its compact form factor and exit-pupil expansion. Despite these advantages, current waveguide displays struggle to integrate visual information with real scenes because they do not produce accommodation-capable virtual content. In this paper, we introduce a lensless accommodation-capable holographic system based on a waveguide. Our system aims to expand the eye-box at the optimal viewing distance that provides the maximum FOV. We devised a formalized CGH algorithm based on bold assumption and two constraints and successfully performed numerical observation simulation. In optical experiments, accommodation-capable images with a maximum horizontal FOV of 7.0 degrees were successfully observed within an expanded eye-box of 9.18 mm at an optimal observation distance of 112 mm.

Hologram Noise Model for Data Augmentation and Deep Learning.

This paper introduces a noise augmentation technique designed to enhance the robustness of state-of-the-art (SOTA) deep learning models against degraded image quality, a common challenge in long-term recording systems. Our method, demonstrated through the classification of digital holographic images, utilizes a novel approach to synthesize and apply random colored noise, addressing the typically encountered correlated noise patterns in such images. Empirical results show that our technique not only maintains classification accuracy in high-quality images but also significantly improves it when given noisy inputs without increasing the training time. This advancement demonstrates the potential of our approach for augmenting data for deep learning models to perform effectively in production under varied and suboptimal conditions.

Generation of Perfect Electron Vortex Beam with a Customized Beam Size Independent of Orbital Angular Momentum.

The electron vortex beam (EVB)-carrying quantized orbital angular momentum (OAM) plays an essential role in a series of fundamental research. However, the radius of the transverse intensity profile of a doughnut-shaped EVB strongly depends on the topological charge of the OAM, impeding its wide applications in electron microscopy. Inspired by the perfect vortex in optics, herein, we demonstrate a perfect electron vortex beam (PEVB), which completely unlocks the constraint between the beam size and the beam's OAM. We design nanoscale holograms to generate PEVBs carrying different quanta of OAM but exhibiting almost the same beam size. Furthermore, we show that the beam size of the PEVB can be readily controlled by only modifying the design parameters of the hologram. The generation of PEVB with a customized beam size independent of the OAM can promote various in situ applications of free electrons carrying OAM in electron microscopy.

Holo-Stroke: Assessing for Immersive Stroke Care Through Stroke Hologram Teleportation.

Background: Augmented reality enables the wearer to see both their physical environment and virtual objects. Holograms could allow 3D video of providers to be transmitted to distant sites, allowing patients to interact with virtual providers as if they are in the same physical space. Our aim was to determine if Tele-Stroke augmented with Holo-Stroke, compared with Tele-Stroke alone, could improve satisfaction and perception of immersion for the patient. Methods: Kinect cameras positioned at 90-degree intervals around the hub practitioner were used. Cameras streamed real-time optical video to a unity point-cloud program where the data were stitched together in a 360-degree view. The resultant hologram was positioned in 3D space and was visible through the head-mounted display by the patient. Radiology images were shared in Tele-Stroke and via hologram. Likert satisfaction questions were administered. Wilcoxon signed-rank testing was used. Results: Each of the 30 neurology clinic participants scored both Tele-Stroke and Holo-Stroke. Out of these, 29 patients completed the assessments (1 failure owing to computer reboot). Average age was 52 years, with 53.3% of the patients being female, 70.0% being White, and 13.3% being Hispanic. Likert scale score median "Overall" was 32 Tele-Stroke versus 48 Holo-Stroke (p < 0.00001), "Immersion" was 5 versus 10 (p < 0.00001), "Beneficial Technique" was 6 versus 10 (p < 0.00001), and "Ability to See Images" was 5 versus 10 (p < 0.00001). Discussion: Holo-Stroke 3D holographic Tele-Stroke exams resulted in feasibility, satisfaction, and high perception of immersion for the patient. Patients were enthusiastic for the more immersive, personal discussion with their provider and a robust way to experience radiology images. Though further assessments are needed, Holo-Stroke can help the provider "be there, not just see there!"

Transanal lateral lymph node dissection with intraoperative hologram support in low rectal cancer.

BACKGROUND: In Japan, the standard treatment for stage II/III advanced low rectal cancer is total mesorectal excision plus lateral lymph node dissection (LLND). There are also recent reports on the use of transanal LLND. However, the transanal anatomy is difficult to understand, and additional support tools are required to improve the surgical safety. The present study examined the utility of holograms with mixed reality as an intraoperative support tool for assessing the complex pelvic anatomy. METHODS: Polygon (stereolithography) files of patients' pelvic organs were created and exported from the SYNAPSE VINCENT imaging system and uploaded into the Holoeyes MD virtual reality software. Three-dimensional images were automatically converted into patient-specific holograms. Each hologram was then installed into a head mount display (HoloLens2), and the surgeons and assistants wore the HoloLens2 when they performed transanal LLND. Twelve digestive surgeons with prior practice in hologram manipulation evaluated the utility of the intraoperative hologram support by means of a questionnaire. RESULTS: Intraoperative hologram support improved the surgical understanding of the lateral lymph node region anatomy. In the questionnaire, 75% of the surgeons answered that the hologram accurately reflected the anatomy, and 92% of the surgeons answered that the anatomy was better understood by simulating the hologram intraoperatively than preoperatively. Moreover, 92% of the surgeons agreed that intraoperative holograms were a useful support tool for improving the surgical safety. CONCLUSIONS: Intraoperative hologram support improved the surgical understanding of the pelvic anatomy for transanal LLND. Intraoperative holograms may represent a next-generation surgical tool for transanal LLND.

Breaking of Wavelength-Dependence in Holographic Wavefront Sensors Using Spatial-Spectral Filtering.

Nowadays, wavefront sensors are widely used to control the shape of the wavefront and detect aberrations of the complex field amplitude in various fields of physics. However, almost all of the existing wavefront sensors work only with quasi-monochromatic radiation. Some of the methods and approaches applied to work with polychromatic radiation impose certain restrictions. However, the contemporary methods of computer and digital holography allow implementing a holographic wavefront sensor that operates with polychromatic radiation. This paper presents a study related to the analysis and evaluation of the error in the operation of holographic wavefront sensors with such radiation.

Design of a Compact Hologram System Capable of 3D Lesion Diagnosis in Clinic.

MOTIVATION: This paper proposes a small-sized hologram system for the 3D imaging of lesions in a clinical environment. In a general hologram system, the distance between the beam-generating device and the screen (400 mm) and the size of the screen must be increased proportionally to obtain excellent image quality. However, in a clinical environment, the beam spread distance and screen size must be reduced. This paper proposes a method for reducing the beam divergence distance and screen size for clinical applications. METHODS: To reduce the beam spread distance and screen size, a beam prism with a 45° refractive index is used to reduce the beam spread distance by 1/3. The direction of the bent light must be adjusted such that it can reach the screen accurately. However, because the reflected light may be refracted owing to the material properties of the mirror and cause loss, this problem can be solved by using a full reflection mirror. RESULTS: The beam spread distance of the designed hologram system is 200 mm. The types of lesions obtained from the 3D images of the hologram include the lung, liver, and colon. The image resolution is 300 × 145. CONCLUSION: If the proposed method is used in a clinical environment, doctors can improve their understanding of the patient quickly and efficiently; thereby, shortening the treatment time. The proposed hologram system is expected to be useful in treatment rooms, operating rooms, and educational programs in medical schools.

Intraoperative holographic image-guided surgery in a transanal approach for rectal cancer.

PURPOSE: Urethral injury is one of the most important complications in transanal total mesorectal excision (TaTME) in male patients with rectal cancer. The purpose of this study was to investigate holographic image-guided surgery in TaTME. METHODS: Polygon (stereolithography) files were created and exported from SYNAPSE VINCENT, and then uploaded into the Holoeyes MD system (Holoeyes Inc., Tokyo, Japan). After uploading the data, the three-dimensional image was automatically converted into a case-specific hologram. The hologram was then installed into the head mount display, HoloLens (Microsoft Corporation, Redmond, WA). The surgeons and assistants wore the HoloLens when they performed TaTME. RESULTS: In a Wi-Fi-enabled operating room, each surgeon, wearing a HoloLens, shared the same hologram and succeeded in adjusting the hologram by making simple hand gestures from their respective angles. The hologram contributed to better comprehension of the positional relationships between the urethra and the surrounding pelvic organs during surgery. All surgeons were able to properly determine the dissection line. CONCLUSIONS: This first experience suggests that intraoperative holograms contributed to reducing the risk of urethral injury and understanding transanal anatomy. Intraoperative holograms have the potential to become a new next-generation surgical support tool for use in spatial awareness and the sharing of information between surgeons.

Recent Advances in Counterfeit Art, Document, Photo, Hologram, and Currency Detection Using Hyperspectral Imaging.

Forgery and tampering continue to provide unnecessary economic burdens. Although new anti-forgery and counterfeiting technologies arise, they inadvertently lead to the sophistication of forgery techniques over time, to a point where detection is no longer viable without technological aid. Among the various optical techniques, one of the recently used techniques to detect counterfeit products is HSI, which captures a range of electromagnetic data. To aid in the further exploration and eventual application of the technique, this study categorizes and summarizes existing related studies on hyperspectral imaging and creates a mini meta-analysis of this stream of literature. The literature review has been classified based on the product HSI has used in counterfeit documents, photos, holograms, artwork, and currency detection.

Vectorial Holograms with Spatially Continuous Polarization Distributions.

Metasurface-based holography presents opportunities for applications that include optical displays, data storage, and optical encryption. Holograms that control polarization are sometimes referred to as vectorial holograms. Most studies on this topic have concerned devices that display different images when illuminated with different polarization states. Fewer studies have demonstrated holographic images whose polarization varies spatially, i.e., as a function of the position within the image. Here, we experimentally demonstrate a vectorial hologram that produces an image with a spatially continuous distribution of polarization states, for the first time to our knowledge. An unlimited number of polarization states can be achieved within the image. Furthermore, the holographic image and its polarization map (polarization vs position in image) are independent. The same image can be thus encoded with different polarization maps. As far as we know, our approach is conceptually new. We anticipate that it could broaden the application scope of metasurface holography.

Kerr Metasurface Enabled by Metallic Quantum Wells.

Optical metasurfaces have emerged as promising candidates for multifunctional devices. Dynamically reconfigurable metasurfaces have been introduced by employing phase-change materials or by applying voltage, heat, or strain. While existing metasurfaces exhibit appealing properties, they do not express any significant nonlinear effects due to the negligible nonlinear responses from the typical materials used to build the metasurface. In this work, we propose and experimentally demonstrate one kind of Kerr metasurface that shows strong intensity-dependent responses. The Kerr metasurface is composed of a top layer of gold antennas, a dielectric spacer, and a ground layer of metallic quantum wells (MQWs). Because of the large Kerr nonlinearity supported by the MQWs, the effective optical properties of the MQWs can change from metallic to dielectric with increasing of the input intensity, leading to dramatic modifications of the metasurface responses. This opens up new routes for potential applications in the field of nonlinear optics.

Metasurfaces with Planar Chiral Meta-Atoms for Spin Light Manipulation.

Spin light (i.e., circularly polarized light) manipulation based on metasurfaces with a controlled geometric phase (i.e., Pancharatnam-Berry (PB) phase) has achieved great successes according to its convenient design and robust performances, by which the phase control is mainly determined by the rotation angle of each meta-atom. This PB phase can be regarded as a global effect for spin light; here, we propose a local phase manipulation for metasurfaces with planar chiral meta-atoms. Planar chiral meta-atoms break fundamental symmetry restrictions and do not need a rotation for these kinds of meta-atoms to manipulate the spin light, which significantly expands the functionality of metasurface as it is incorporated with other modulations (e.g., PB phase, propagation phase). As an example, spin-decoupled holographic imaging is demonstrated with robust and broadband properties. Our work definitely enriches the design of metasurfaces and may trigger more exciting chiral-optics applications.

Point-Source Geometric Metasurface Holography.

Geometric metasurfaces have shown great potential in holography due to their straightforward geometric nature of phase control. The incident angles, spins, and wavelengths of the light provide various degrees of freedom to multiplex metasurface holographic images, which, however, are usually interrelated and hence challenging to be fully decoupled. Here, we report a synergetic recipe to break such seemingly inevitable interrelation by incorporating an effective point source (a pinhole), with which the spin, wavelength, and coordinate of the point source can be fully decoupled in meta-holograms. We experimentally demonstrate spin-decoupled, full-colored metasurface holography and dynamic holography controlled with the position of the point source. The significance of this work is not merely to offer an alternative approach to break the interrelation limitations of the geometric metasurface, but more importantly, it provides a promising route for point sources in reality to realize advanced functionalities with meta-optics, such as single-photon holography, fluorescence holography, etc.

Digital Transformation Will Change Medical Education and Rehabilitation in Spine Surgery.

The concept of minimally invasive spine therapy (MIST) has been proposed as a treatment strategy to reduce the need for overall patient care, including not only minimally invasive spine surgery (MISS) but also conservative treatment and rehabilitation. To maximize the effectiveness of patient care in spine surgery, the educational needs of medical students, residents, and patient rehabilitation can be enhanced by digital transformation (DX), including virtual reality (VR), augmented reality (AR), mixed reality (MR), and extended reality (XR), three-dimensional (3D) medical images and holograms; wearable sensors, high-performance video cameras, fifth-generation wireless system (5G) and wireless fidelity (Wi-Fi), artificial intelligence, and head-mounted displays (HMDs). Furthermore, to comply with the guidelines for social distancing due to the unexpected COVID-19 pandemic, the use of DX to maintain healthcare and education is becoming more innovative than ever before. In medical education, with the evolution of science and technology, it has become mandatory to provide a highly interactive educational environment and experience using DX technology for residents and medical students, known as digital natives. This study describes an approach to pre- and intraoperative medical education and postoperative rehabilitation using DX in the field of spine surgery that was implemented during the COVID-19 pandemic and will be utilized thereafter.

Three-Dimensional Holographic Guidance, Navigation, and Control (3D-GNC) for Endograft Positioning in Porcine Aorta: Feasibility Comparison With 2-Dimensional X-Ray Fluoroscopy.

OBJECTIVES: Intraprocedural deployment of endovascular devices during complex aortic repair with 2-dimensional (2D) x-ray fluoroscopic guidance poses challenges in terms of accurate delivery system positioning and increased risk of x-ray radiation exposure with prolonged fluoroscopy times, particularly in unfavorable anatomy. The objective of this study was to assess feasibility of using an augmented reality (AR) system to position and orient a modified aortic endograft delivery system in comparison with standard fluoroscopy. MATERIALS AND METHODS: The 3-dimensional guidance, navigation, and control (3D-GNC) prototype system was developed for eventual integration with the Intra-Operative Positioning System (IOPS, Centerline Biomedical, Cleveland, OH) to project spatially registered 3D holographic representations of the subject-specific aorta for intraoperative guidance and coupled with an electromagnetically (EM) tracked delivery system for intravascular navigation. Numerical feedback for controlling the endograft landing zone distance and ostial alignment was holographically projected on the operative field. Visualization of the holograms was provided via a commercially available AR headset. A Zenith Spiral-Z AAA limb stent-graft was modified with a scallop, 6 degree-of-freedom EM sensor for tracking, and radiopaque markers for fluoroscopic visualization. In vivo, 10 interventionalists independently positioned and oriented the delivery system to the ostia of renal or visceral branch vessels in anesthetized swine via open femoral artery access using 3D-GNC and standard fluoroscopic guidance. Procedure time, fluoroscopy time, cumulative air kerma, and contrast material volume were recorded for each technique. Positioning and orientation accuracy was determined by measuring the target landing-zone distance error (δLZE) and the scallop-ostium angular alignment error (θSOE) using contrast-enhanced cone beam computed tomography imaging after each positioning for each technique. Mean, standard deviation, and standard error are reported for the performance variables, and Student's t tests were used to evaluate statistically significant differences in performance mean values of 3D-GNC and fluoroscopy. RESULTS: Technical success for the use of 3D-GNC to orient and position the endovascular device at each renal-visceral branch ostium was 100%. 3D-GNC resulted in 56% decrease in procedure time in comparison with standard fluoroscopic guidance (p<0.001). The 3D-GNC system was used without fluoroscopy or contrast-dye administration. Positioning accuracy was comparable for both techniques (p=0.86), while overall orientation accuracy was improved with the 3D-GNC system by 41.5% (p=0.008). CONCLUSIONS: The holographic 3D-GNC system demonstrated improved accuracy of aortic stent-graft positioning with significant reductions in fluoroscopy time, contrast-dye administration, and procedure time.

A 3D Hologram With Mixed Reality Techniques to Improve Understanding of Pulmonary Lesions Caused by COVID-19: Randomized Controlled Trial.

BACKGROUND: The COVID-19 outbreak has now become a pandemic and has had a serious adverse impact on global public health. The effect of COVID-19 on the lungs can be determined through 2D computed tomography (CT) imaging, which requires a high level of spatial imagination on the part of the medical provider. OBJECTIVE: The purpose of this study is to determine whether viewing a 3D hologram with mixed reality techniques can improve medical professionals' understanding of the pulmonary lesions caused by COVID-19. METHODS: The study involved 60 participants, including 20 radiologists, 20 surgeons, and 20 medical students. Each of the three groups was randomly divided into two groups, either the 2D CT group (n=30; mean age 29 years [range 19-38 years]; males=20) or the 3D holographic group (n=30; mean age 30 years [range 20=38 years]; males=20). The two groups completed the same task, which involved identifying lung lesions caused by COVID-19 for 6 cases using a 2D CT or 3D hologram. Finally, an independent radiology professor rated the participants' performance (out of 100). All participants in two groups completed a Likert scale questionnaire regarding the educational utility and efficiency of 3D holograms. The National Aeronautics and Space Administration Task Load Index (NASA-TLX) was completed by all participants. RESULTS: The mean task score of the 3D hologram group (mean 91.98, SD 2.45) was significantly higher than that of the 2D CT group (mean 74.09, SD 7.59; P<.001). With the help of 3D holograms, surgeons and medical students achieved the same score as radiologists and made obvious progress in identifying pulmonary lesions caused by COVID-19. The Likert scale questionnaire results showed that the 3D hologram group had superior results compared to the 2D CT group (teaching: 2D CT group median 2, IQR 1-2 versus 3D group median 5, IQR 5-5; P<.001; understanding and communicating: 2D CT group median 1, IQR 1-1 versus 3D group median 5, IQR 5-5; P<.001; increasing interest: 2D CT group median 2, IQR 2-2 versus 3D group median 5, IQR 5-5; P<.001; lowering the learning curve: 2D CT group median 2, IQR 1-2 versus 3D group median 4, IQR 4-5; P<.001; spatial awareness: 2D CT group median 2, IQR 1-2 versus 3D group median 5, IQR 5-5; P<.001; learning: 2D CT group median 3, IQR 2-3 versus 3D group median 5, IQR 5-5; P<.001). The 3D group scored significantly lower than the 2D CT group for the "mental," "temporal," "performance," and "frustration" subscales on the NASA-TLX. CONCLUSIONS: A 3D hologram with mixed reality techniques can be used to help medical professionals, especially medical students and newly hired doctors, better identify pulmonary lesions caused by COVID-19. It can be used in medical education to improve spatial awareness, increase interest, improve understandability, and lower the learning curve. TRIAL REGISTRATION: Chinese Clinical Trial Registry ChiCTR2100045845; http://www.chictr.org.cn/showprojen.aspx?proj=125761.