AudioGest: Gesture-based Interaction for Virtual Reality using Audio Devices.

Current virtual reality (VR) system takes gesture interaction based on camera, handle and touch screen as one of the mainstream interaction methods, which can provide accurate gesture input for it. However, limited by application forms and the volume of devices, these methods cannot extend the interaction area to such surfaces as walls and tables. To address the above challenge, we propose AudioGest, a portable, plug-and-play system that detects the audio signal generated by finger tapping and sliding on the surface through a set of microphone devices without extensive calibration. First, an audio synthesis-recognition pipeline based on micro-contact dynamics simulation is constructed to generate modal audio synthesis from different materials and physical properties. Then the accuracy and effectiveness of the synthetic audio are verified by mixing the synthetic audio with real audio proportionally as the training sets. Finally, a series of desktop office applications are developed to demonstrate the application potential of AudioGest's scalability and versatility in VR scenarios.

Analytical Perspectives on Cement Sheath Integrity: A Comprehensive Review of Theoretical Research.

The cement sheath, serving as the primary element of well barriers, plays a crucial role in maintaining zonal isolation, protecting the casing from corrosion, and providing mechanical support. As the petroleum industry shifts from conventional to deep unconventional resources, the service environment for cement sheaths has become increasingly complex. High temperatures, high pressures, cyclic loading, and thermal stresses in downhole conditions have significantly increased the risk of cement sheath failure. A growing trend toward theoretical analysis of stress distribution, failure modes, and control mechanisms within the casing-cement sheath-formation system is evident. This paper comprehensively reviews theoretical research on cement sheath integrity from four key perspectives: (1) the concept of cement sheath integrity failure, (2) cement sheath constitutive models, (3) analytical models of the cement sheath-casing-formation system, and (4) numerical simulations of the cement sheath-casing-formation system. Through these discussions, this review provides profound insights into cement sheath integrity failure and offers valuable guidance for future research and practices.

p38 MAPK inhibitor SB202190 suppresses ferroptosis in the glutamate-induced retinal excitotoxicity glaucoma model.

JOURNAL/nrgr/04.03/01300535-202410000-00031/figure1/v/2024-02-06T055622Z/r/image-tiff Glutamate excitotoxicity has been shown to play an important role in glaucoma, and glutamate can induce ferroptosis. The p38 mitogen-activated protein kinase (MAPK) pathway inhibitor SB202190 has a potential ability to suppress ferroptosis, and its downstream targets, such as p53, have been shown to be associated with ferroptosis. However, whether ferroptosis also occurs in retinal ganglion cells in response to glutamate excitotoxicity and whether inhibition of ferroptosis reduces the loss of retinal ganglion cells induced by glutamate excitotoxicity remain unclear. This study investigated ferroptosis in a glutamate-induced glaucoma rat model and explored the effects and molecular mechanisms of SB202190 on retinal ganglion cells. A glutamate-induced excitotoxicity model in R28 cells and an N-methyl-D-aspartate-induced glaucoma model in rats were used. In vitro experiments showed that glutamate induced the accumulation of iron and lipid peroxide and morphological changes of mitochondria in R28 cells, and SB202190 inhibited these changes. Glutamate induced the levels of p-p38 MAPK/p38 MAPK and SAT1 and decreased the expression levels of ferritin light chain, SLC7A11, and GPX4. SB202190 inhibited the expression of iron death-related proteins induced by glutamate. In vivo experiments showed that SB202190 attenuated N-methyl-D-aspartate-induced damage to rat retinal ganglion cells and improved visual function. These results suggest that SB202190 can inhibit ferroptosis and protect retinal ganglion cells by regulating ferritin light chain, SAT1, and SLC7A11/Gpx4 pathways and may represent a potential retina protectant.

Ripa-56 protects retinal ganglion cells in glutamate-induced retinal excitotoxic model of glaucoma.

Glaucoma is a prevalent cause of blindness globally, characterized by the progressive degeneration of retinal ganglion cells (RGCs). Among various factors, glutamate excitotoxicity stands out as a significant contributor of RGCs loss in glaucoma. Our study focused on Ripa-56 and its protective effect against NMDA-induced retinal damage in mice, aiming to delve into the potential underlying mechanism. The R28 cells were categorized into four groups: glutamate (Glu), Glu + Ripa-56, Ripa-56 and Control group. After 24 h of treatment, cell death was assessed by PI / Hoechst staining. Mitochondrial membrane potential changes, apoptosis and reactive oxygen species (ROS) production were analyzed using flow cytometry. The alterations in the expression of RIP-1, p-MLKL, Bcl-2, BAX, Caspase-3, Gpx4 and SLC7A11 were examined using western blot analysis. C57BL/6j mice were randomly divided into NMDA, NMDA + Ripa-56, Ripa-56 and control groups. Histological changes in the retina were evaluated using hematoxylin and eosin (H&E) staining. RGCs survival and the protein expression changes of RIP-1, Caspase-3, Bcl-2, Gpx4 and SLC7A11 were observed using immunofluorescence. Ripa-56 exhibited a significant reduction in the levels of RIP-1, p-MLKL, Caspase-3, and BAX induced by glutamate, while promoting the expression of Bcl-2, Gpx-4, and SLC7A1 in the Ripa-56-treated group. In our study, using an NMDA-induced normal tension glaucoma mice model, we employed immunofluorescence and H&E staining to observe that Ripa-56 treatment effectively ameliorated retinal ganglion cell loss, mitigating the decrease in retinal ganglion cell layer and bipolar cell layer thickness caused by NMDA. In this study, we have observed that Ripa-56 possesses remarkable anti- necroptotic, anti-apoptotic and anti-ferroptosis properties. It demonstrates the ability to combat not only glutamate-induced excitotoxicity in R28 cells, but also NMDA-induced retinal excitotoxicity in mice. Therefore, Ripa-56 could be used as a potential retinal protective agent.

A new chromosome-scale duck genome shows a major histocompatibility complex with several expanded multigene families.

BACKGROUND: The duck (Anas platyrhynchos) is one of the principal natural hosts of influenza A virus (IAV), harbors almost all subtypes of IAVs and resists to many IAVs which cause extreme virulence in chicken and human. However, the response of duck's adaptive immune system to IAV infection is poorly characterized due to lack of a detailed gene map of the major histocompatibility complex (MHC). RESULTS: We herein reported a chromosome-scale Beijing duck assembly by integrating Nanopore, Bionano, and Hi-C data. This new reference genome SKLA1.0 covers 40 chromosomes, improves the contig N50 of the previous duck assembly with highest contiguity (ZJU1.0) of more than a 5.79-fold, surpasses the chicken and zebra finch references in sequence contiguity and contains a complete genomic map of the MHC. Our 3D MHC genomic map demonstrated that gene family arrangement in this region was primordial; however, families such as AnplMHCI, AnplMHCIIß, AnplDMB, NKRL (NK cell receptor-like genes) and BTN underwent gene expansion events making this area complex. These gene families are distributed in two TADs and genes sharing the same TAD may work in a co-regulated model. CONCLUSIONS: These observations supported the hypothesis that duck's adaptive immunity had been optimized with expanded and diversified key immune genes which might help duck to combat influenza virus. This work provided a high-quality Beijing duck genome for biological research and shed light on new strategies for AIV control.

Design of an image-based BRDF measurement method using a catadioptric multispectral capture and a real-time Lambert calibration.

By utilizing a catadioptric system and a calibration Lambertian sample, a compact measurement method of bidirectional reflectance distribution function (BRDF) has been proposed for rapid and accurate measurement. With the help of an ellipsoidal dome mirror, a hyperboloid mirror, and a high-resolution camera, spatial reflectance distributions from reflected directions with a large field of view (FOV) can be obtained. The built-in Lambertian standard allows for real-time calibration to account for fluctuations in the illumination spectrum, effectively reducing the measurement drift and achieving a high accuracy. Moreover, a multispectral camera captures images at 8 spectral bands for accurate spectral color reconstruction from different directions. To verify the method, a prototype capable of fast, high-resolution measurements with a large FOV has been developed for characterizing the scattering properties of objects. It achieves a measured angular range up to 160°. Multispectral BRDF data for each sample can be obtained within 5 minutes with an angular resolution of less than 0.6°. Eight ceramic samples with different colors were selected for the verification of measurement accuracy, and their mean relative bias of BRDF measurement was found to be as low as 2.5%.

Role of epigenetic regulation in glaucoma.

Glaucoma is the world's leading irreversible blinding eye disease. Lowering intraocular pressure is currently the only effective clinical treatment. However, there is a lack of long-acting IOP-lowering drugs, and some patients still experience retinal ganglion cell loss even with good intraocular pressure control. Currently, there is no effective method for neuroprotection and regeneration in clinical practice for glaucoma. In recent years, epigenetics has been widely researched and reported for its role in glaucoma's neuroprotection and regeneration. This article reviews the changes in histone modifications, DNA methylation, non-coding RNA, and m6A methylation in glaucoma, aiming to provide new perspectives for glaucoma management, protection of retinal ganglion cells, and axon regeneration by understanding epigenetic alterations.

A flexible optoacoustic blood 'stethoscope' for noninvasive multiparametric cardiovascular monitoring.

Quantitative and multiparametric blood analysis is of great clinical importance in cardiovascular disease diagnosis. Although there are various methods to extract blood information, they often require invasive procedures, lack continuity, involve bulky instruments, or have complicated testing procedures. Flexible sensors can realize on-skin assessment of several vital signals, but generally exhibit limited function to monitor blood characteristics. Here, we report a flexible optoacoustic blood 'stethoscope' for noninvasive, multiparametric, and continuous cardiovascular monitoring, without requiring complicated procedures. The optoacoustic blood 'stethoscope' features the light delivery elements to illuminate blood and the piezoelectric acoustic elements to capture light-induced acoustic waves. We show that the optoacoustic blood 'stethoscope' can adhere to the skin for continuous and non-invasive in-situ monitoring of multiple cardiovascular biomarkers, including hypoxia, intravascular exogenous agent concentration decay, and hemodynamics, which can be further visualized with a tailored 3D algorithm. Demonstrations on both in-vivo animal trials and human subjects highlight the optoacoustic blood 'stethoscope''s potential for cardiovascular disease diagnosis and prediction.

Effect of surrounding objects in the adapting scene on chromatic adaptation.

Most of the existing chromatic adaptation transforms (CATs) were developed for flat uniform stimuli presented in a uniform background, which substantially simplifies the complexity of the real scene by excluding surrounding objects from the viewing field. The impact of the background complexity, in terms of the spatial properties of the objects surrounding the stimulus, on chromatic adaptation is ignored in most CATs. This study systematically investigated how the background complexity and color distribution affect the adaptation state. Achromatic matching experiments were conducted in an immersive lighting booth, with the illumination varying in chromaticity and the adapting scene varying in surrounding objects. Results show that compared to the uniform adapting field, increasing the scene complexity can significantly improve the degree of adaptation for the Planckian illuminations with low CCT levels. In addition, the achromatic matching points are substantially biased by the color of the surrounding object, implying the interactive effect of the illumination color and the dominant scene color on the adapting white point.

Growth of nanostructured Cu3Al alloy films by magnetron sputtering for non-enzymatic glucose-sensing applications.

Enzymatic glucose sensors usually exhibit excellent sensitivity and selectivity but suffer from poor stability due to the negative influence of temperature and humidity on enzyme molecules. As compared to enzymatic glucose sensors, non-enzymatic counterparts are generally more stable but are facing challenges in concurrently improving both sensitivity and selectivity of a trace amount of glucose molecules in physiological samples such as saliva and sweat. Here, a novel non-enzymatic glucose sensor based on nanostructured Cu3Al alloy films has been fabricated by a facile magnetron-sputtering followed by controllable electrochemical etching approach. Since the metal Al is more reductive than Cu, by selectively etching aluminum in the Cu3Al alloys, nanostructured alloy films were obtained with increased surface contact area and electrocatalytic active sites which resulted in enhanced glucose-sensing performance. Thus, non-enzymatic glucose sensors based on nanostructured Cu3Al alloy films not only exhibited a high sensitivity of 1680 µA mM-1 cm-2 but also achieved a reliable selectivity to glucose without interference by other species in physiological samples. Consequently, this study sparked the potential for the development of non-enzymatic biosensors for the continuous monitoring of blood glucose levels with high sensitivity and impressive selectivity for glucose molecules.

A novel phytopathogen Erwinia sorbitola sp. nov., isolated from the feces of ruddy shelducks.

The species in the genus Erwinia are Gram-stain-negative, facultatively anaerobic, motile, and rod-shaped. Most species in the genus Erwinia are phytopathogens. Also, Erwinia persicina was involved in several human infections. Based on the reverse microbial etiology principles, it is worth analyzing the pathogenicity of species in this genus. In this study, we isolated and sequenced two species of Erwinia. Phylogenetic, phenotypic, biochemical, and chemotaxonomic analyses were performed to identify its taxonomy position. The virulence tests on plant leaves and pear fruits were used to identify the plant pathogenicity of two species of Erwinia. Bioinformatic methods predicted the possible pathogenic determinants based on the genome sequence. Meanwhile, adhesion, invasion, and cytotoxicity assays on RAW 264.7 cells were applied to identify animal pathogenicity. We isolated two Gram-stain-negative, facultatively anaerobic, motile, and rod-shaped strains from the feces of ruddy shelducks in the Tibet Plateau of China, designated J780T and J316. Distinct phylogenetic, genomic, phenotypic, biochemical, and chemotaxonomic characters of J780T and J316 identified they were novel species and belonged to the genus Erwinia, for which the name Erwinia sorbitola sp. nov. was proposed, the type strain was J780T (= CGMCC 1.17334T = GDMCC 1.1666T = JCM 33839T). Virulence tests showed blight and rot on the leaves and pear fruits confirmed Erwinia sorbitola sp. nov. was a phytopathogen. Predicted gene clusters of motility, biofilm formation, exopolysaccharides, stress survival, siderophores, and Type VI secretion system might be the causes of pathogenicity. In addition, predicted polysaccharide biosynthesis gene clusters on the genome sequence, and the high capacity for adhesion, invasion, and cytotoxicity to animal cells confirmed it has pathogenicity on animals. In conclusion, we isolated and identified a novel phytopathogen Erwinia sorbitola sp. nov. in ruddy shelducks. A predefined pathogen is beneficial for preventing from suffering potential economic losses caused by this new pathogen.

Identification of alternative splicing events related to fatty liver formation in duck using full-length transcripts.

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) is one of most common diseases in the world. Recently, alternative splicing (AS) has been reported to play a key role in NAFLD processes in mammals. Ducks can quickly form fatty liver similar to human NAFLD after overfeeding and restore to normal liver in a short time, suggesting that ducks are an excellent model to unravel molecular mechanisms of lipid metabolism for NAFLD. However, how alternative splicing events (ASEs) affect the fatty liver process in ducks is still unclear. RESULTS: Here we identify 126,277 unique transcripts in liver tissue from an overfed duck (77,237 total transcripts) and its sibling control (69,618 total transcripts). We combined these full-length transcripts with Illumina RNA-seq data from five pairs of overfed ducks and control individuals. Full-length transcript sequencing provided us with structural information of transcripts and Illumina RNA-seq data reveals the expressional profile of each transcript. We found, among these unique transcripts, 30,618 were lncRNAs and 1,744 transcripts including 155 lncRNAs and 1,589 coding transcripts showed significantly differential expression in liver tissues between overfed ducks and control individuals. We also detected 27,317 ASEs and 142 of them showed significant relative abundance changes in ducks under different feeding conditions. Full-length transcript profiles together with Illumina RNA-seq data demonstrated that 10 genes involving in lipid metabolism had ASEs with significantly differential abundance in normally fed (control) and overfed ducks. Among these genes, protein products of five genes (CYP4F22, BTN, GSTA2, ADH5, and DHRS2 genes) were changed by ASEs. CONCLUSIONS: This study presents an example of how to identify ASEs related to important biological processes, such as fatty liver formation, using full-length transcripts alongside Illumina RNA-seq data. Based on these data, we screened out ASEs of lipid-metabolism related genes which might respond to overfeeding. Our future ability to explore the function of genes showing AS differences between overfed ducks and their sibling controls, using genetic manipulations and co-evolutionary studies, will certainly extend our knowledge of genes related to the non-pathogenic fatty liver process.

Failure Analysis of Cement Sheath Mechanical Integrity Based on the Statistical Damage Variable.

Maintaining the cement sheath mechanical integrity is the key to ensuring the benefit and safety of oil and gas well drilling and production. The main function of the cement sheath is to isolate oil and gas from water layers, which prevents the formation fluid from channeling to other layers. At present, how to effectively evaluate the cement sheath sealing performance is the fundamental problem to be solved urgently. This paper first carried out the cement sheath annulus isolation experiment and analyzed the main forms of cement sheath seal failure. Then, the interaction of the cement sheath, casing, and surrounding rock in the initial state and subsequent wellbore operations was explained. An analysis model for the cement sheath mechanical integrity incorporating the nonlinear elastic constitutive equation was proposed. Based on the statistical damage variable in continuum mechanics theory, a damage variable was established. The results show that the main form of cement sheath integrity failure is tensile crack damage and micro-annulus caused by plastic yielding. The damage variable can quantitatively describe the cement sheath mechanical integrity. The field case analysis shows that the damage variable is highly correlated with wellbore pressure and also verifies the applicability of the variable. Reducing wellbore pressure will help maintain the mechanical integrity of the cement sheath, providing sealing performance. This research can provide a reference for designing the mechanical properties of the cement sheath and improving the sealing ability of the cement sheath.

Comparison of clinical outcomes between cystotome-assisted prechop phacoemulsification surgery and femtosecond laser-assisted cataract surgery for hard nucleus cataracts.

BACKGROUND/OBJECTIVES: To compare the safety and efficacy of cystotome-assisted prechop phacoemulsification surgery (CAPPS) and femtosecond laser-assisted cataract surgery (FLACS) in patients with hard nucleus cataract. SUBJECTS/METHODS: Ninety-six eyes of 64 patients with grade IV hard nucleus cataract were assigned to 1 of the 2 groups (49 CAPPS and 47 FLACS). Follow-up visits were performed at 1 day, 1 week, 1 month, 3 months, 6 months, and 1 year, and the outcome measures comprised ultrasound power, effective phacoemulsification time (EPT), corrected distance visual acuity (CDVA), endothelial cell density (ECD), corneal endothelium cell loss rate (ECL), central corneal thickness (CCT), and intraoperative and postoperative complications. RESULTS: The ultrasound power and EPT were lower in the CAPPS group (p = 0.03 and <0.0001, respectively). Patients in both groups gained better CDVA postoperatively. The ECD value decreased at each follow-up visit and did not return to the preoperative level; FLACS resulted in greater endothelial cell loss compared to CAPPS. CCT increased immediately after the surgery and decreased thereafter. The mean CCT value returned to the preoperative level 3 months postoperatively in the CAPPS group, while in the FLACS group, CCT value took 6 months to return to the preoperative level. Miosis was more likely to occur in the FLACS group. CONCLUSIONS: Due to its efficacy and cost-effectiveness, CAPPS is worth promoting and applying to clinical work in the future.

Longitudinal association between visual disability and cognitive function among middle-aged and older adults in China.

BACKGROUND/AIMS: To determine the associations between visual disability and cognitive decline in Chinese middle-aged and older adults. METHODS: A total of 6748 subjects were enrolled into this longitudinal, population-based, nationally representative study from two waves of the China Health and Retirement Longitudinal Study. Lagged dependent variable regression was used to model the independent associations between self-reported visual disability and cognitive function including memory and mental status. RESULTS: The mean age of the 6748 individuals was 56.33 years, and 3350 (49.6%) were women. The prevalence of visual disability was 3.8%, which increased with age (p<0.001). Both memory and mental status score worsened over time (all p<0.001). After controlling for covariates, lagged dependent variable regression models showed that visual disability at baseline was significantly associated with memory decline after 7 years (ß=-0.252, p=0.046). After stratifying by age groups, this association was only significant in the 55-64 age group (ß=-0.372, p=0.033). In addition, both memory and mental status in 2011 predicted memory decline over 7 years (p=0.024 and p=0.045, respectively). CONCLUSIONS: Our results suggest that visual disability may be a risk factor of memory decline, but not mental status among middle-aged and elderly adults in China. Future studies are needed to further corroborate the association between visual disability and cognitive decline and to determine whether interventions to preserve good visual function can prevent cognitive decline.

Transition type influences the adaptation state under dichromatic illuminations.

The CATs models proposed over these years (such as CMCCAT97, CAT02 and CAT16) were derived from simple stimuli surrounded by a uniform background with a single illuminant. However, the real scene always consists of more than one illumination, especially in many artificially lit environments. Some previous studies indicate an influence of the transition type between two illuminations on the adaptation state, but the visual data is insufficient to conclude a general trend applicable for any color pair. To systematically investigate how the transition type and illumination color pair interactively influence the adapted white point and degree of adaptation, a series of achromatic matching experiments were conducted under (simultaneously) spatially dichromatic illuminations. Transition type was found to have an impact on the adaptation state, but it is significant only for an illumination pair with a large color difference. In addition, for those sharp-transitioned dichromatic illuminations, the illumination that more easily gets adapted tends to have a higher contribution to the adapted white point than the other one. A more comprehensive CAT model for dichromatic illuminations was derived from the collected visual data.

Imaging stretching and displacement using gradient-index elements during the lens design process.

In this study, we propose an approach to stretch or translate images using gradient-index (GRIN) elements with a rotationally symmetric shape in lens systems. In this method, the GRIN material, instead of optical surfaces, are utilized to enable a breaking of rotational symmetry for the two image translations. GRIN expression with anamorphic and tilting terms is introduced. A pair of GRIN elements in front of the given system alters the magnification in two orthogonal directions using the anamorphic terms in the expression, which realizes image stretching. A pair of GRIN elements with tilting terms is used after the given system tilts the optical path to achieve a transverse displacement of the image. The structure of the given system remains unchanged when these translations are performed. A design method for the GRIN elements is presented. Additionally, a design example is presented whose image is stretched by 1.33 times in one direction and displaced to one side of its axis to demonstrate the feasibility of the proposed approach. The approach in this study may enable novel imaging GRIN lens system designs with flexible image positions or special optical functions.

Mechanisms of NO-Mediated Protein S-Nitrosylation in the Lens-Induced Myopia.

Background: Myopia is a chronic ocular disease, emerging as the most common type of refractive error. This study intends to preliminarily explore the roles of protein S-nitrosylation of nitric oxide (NO) in the regulation of myopia by detecting the expression of neuronal nitric oxide synthase (nNOS) and downstream S-nitrosylation, using the animal model of lens-induced myopia (LIM) in mice. Methods: The 3-week-old C57BL/6 J mice were divided into three groups: group I, lens-induced 0-week group (take eyeballs at the age of 3 weeks); group II, self-control eyes of experimental group (take eyeballs at the age of 7 weeks); and group III, lens-induced 4-week group (take eyeballs at the age of 7 weeks). The diopter and axial length of each group were measured by streak retinoscopes and optical coherence tomography (OCT) before and after model establishment. The protein expressions and locations of nNOS and S-nitrosylated proteins (PSNOs) were measured by western blot and immunofluorescence staining. Site-specific proteomic for protein S-nitrolysation was used to detect the existence and location of S-nitrosylation proteins in the retina of myopic and nonmyopic mice. The Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and motif enrichment analyses were performed. The differential sites were analyzed by GO, KEGG, and motif. Irreversible biotinylation procedure combined with protein purification and western blot was used to detect the protein expression of α-enolase (ENO1), a key player in the hypoxia-related signal pathway. Results: The expressions of nNOS and PSNOs were significantly lower in the retina of experimental eyes than that in self-control eyes and 3-week-old baseline group. A total of 595 S-nitrosylated proteins, 709 S-nitrosylated peptides, and 708 S-nitrosylated sites were identified by site-specific S-nitrolysation proteomics in the retina of myopic and control eyes. A total of 19 differentiation loci were screened, of which 13 sites were downregulated and 6 sites were upregulated in experimental eyes compared with the self-control group. Specifically, the expression of SNO-ENO1 was significantly lower in the retina of experimental eyes than that in self-control eyes and 3-week-old baseline group. Conclusion: LIM induces the decrease of nNOS and PSNO protein levels in the retina of myopic mice. NO-mediated nonclassical protein S-nitrosylation modification may play an important role in the regulation of lens-induced myopia. ENO1 may be a key factor in the regulation of S-nitrosylation modification of myopia.

Design, analysis and optimization of a waveguide-type near-eye display using a pin-mirror array and a concaved reflector.

Waveguides have become one of the most promising optical combiners for see-through near-eye displays due to the thickness, weight, and transmittance. In this study, we propose a waveguide-type near-eye display using a pin-mirror array and a concaved reflector with a compact outlook, optimized image uniformity and stray light. Issues have been discussed in detail, which include field of view (FOV), eye-box, resolution, depth of field (DOF), display uniformity and stray light artifacts. It can be shown that the DOF can be extended (when compared with traditional waveguide-type near-eye displays) to alleviate the vergence-accommodation conflict (VAC) problem, and the uniformity & stray light can be improved with an optimal structure. Moreover, reflective surfaces have been introduced as the input and output coupling with a compact outlook, an easy-processing structure and the achromatic performance. A prototype based on the proposed method have been successfully developed, and virtual images with an extended DOF can be shown along with the real-world.

Design of a dual focal-plane near-eye display using diffractive waveguides and multiple lenses.

We propose a method to construct a compact dual focal-plane optical see-through near-eye display using diffractive waveguides and multiple lenses. A virtual image from a display device is projected into a three-grating waveguide using an objective lens, and a virtual image can be shown at a far distance with an extended eye box. One negative lens is employed to reduce the focus distance of the virtual image, and a corresponding positive lens is used to compensate for the distortion and accommodation errors. Thus, not only can a virtual image with a near distance be achieved, but also a virtual plane with a further distance can be generated by introducing another projection module and waveguide. Only two waveguides and two pieces of lenses are used in front of one eye to obtain a lightweight outlook. To verify the proposed method, a proof-of-concept prototype was developed to provide vivid virtual images at different depths in front of the human eye.