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| 1 | Iterative freeform lens design for optical field control显示文摘It is still very challenging to determine a freeform lens for converting a given input beam into a prescribed output beam where not only the irradiance distribution but also the phase distribution hardly can be expressed analytically.Difficulties arise because the ray mapping from the input beam to the output beam is not only intertwined with the required double freeform surfaces but also intertwined with the output phase distribution,whose gradient represents the directions of the output rays.Direct determination of such a problem is very difficult.Here,we develop a special iterative wavefront tailoring(IWT)method to tackle this problem.In a certain iteration,the current calculation data of the double freeform surfaces and the output phase gradient are used to update the coefficients of a Monge–Ampère equation describing an intermediate wavefront next to the entrance freeform surface.The solution to the wavefront equation could lead to an improved ray mapping to be used to update the corresponding phase gradient data and reconstruct the double freeform surfaces.In a demonstrative example that deviates much from the paraxial or small-angle approximation,the new IWT method can generate a freeform lens that performs much better than that designed by a conventional ray mapping method for producing two irradiance distributions in the forms of numerals'1'and'2'on two successive targets,respectively. | ZEXIN FENG DEWEN CHENG YONGTIAN WANG | 2021 | Photonics Research2021，9，9： | 7 |
| 2 | Design and manufacture AR head-mounted displays:A review and outlook显示文摘Augmented reality head-mounted displays(AR-HMDs)enable users to see real images of the outside world and visualize virtual information generated by a computer at any time and from any location,making them useful for various applications.The manufacture of AR-HMDs combines the fields of optical engineering,optical materials,optical coating,precision manufacturing,electronic science,computer science,physiology,ergonomics,etc.This paper primarily focuses on the optical engineering of AR-HMDs.Optical combiners and display devices are used to combine real-world and virtual-world objects that are visible to the human eye.In this review,existing AR-HMD optical solutions employed for optical combiners are divided into three categories:optical solutions based on macro-,micro-,and nanooptics.The physical principles,optical structure,performance parameters,and manufacturing process of different types of AR-HMD optical solutions are subsequently analyzed.Moreover,their advantages and disadvantages are investigated and evaluated.In addition,the bottlenecks and future development trends in the case of AR-HMD optical solutions are discussed. | Dewen Cheng Qiwei Wang Yue Liu Hailong Chen Dongwei Ni Ximeng Wang Cheng Yao Qichao Hou Weihong Hou Gang Luo Yongtian Wang | 2021 | Light(Advanced Manufacturing)2021，2，3： | 6 |
| 3 | Freeform OST-HMD system with large exit pupil diameter and vision correction capability显示文摘Compactness and light weight,large exit pupil diameter and distance,small distortion for virtual image,and see-through light paths are pivotal factors to achieve a better,wearable experience of optical see-through headmounted displays(OST-HMDs).In addition,light efficiency of the virtual image light path is an important factor for heat dissipation in HMD devices.This paper presents a new type of OST-HMD optical system that includes three wedge-shaped freeform prisms and two symmetric lenses.Based on a 0.71 in.microdisplay,an OST-HMD prototype with a diagonal field of view(FOV)of 45.3°,an F-number(F/#)of 1.8,an exit pupil size of 12 mm×8 mm,and an eye relief of 18 mm is demonstrated.The maximum value of distortion of the final system is 0.6%and 0.4%for virtual image and see-through light path,respectively.The overall dimension of the optical system per eye is no larger than 30 mm(width)×40 mm(height)×14 mm(thickness),and the weight of the optical module including lenses,holder,and microdisplay is 12.8 g.The light efficiency of the virtual image light path is up to 50%higher than those of other OST-HMD optical solutions. | DEWEN CHENG JIAXI DUAN HAILONG CHEN HE WANG DANYANG LI QIWEI WANG QICHAO HOU TONG YANG WEIHONG HOU DONGHUA WANG XIAOYU CHI BIN JIANG YONGTIAN WANG | 2022 | Photonics Research2022，10，1： | 5 |
| 4 | Geochemistry of trace elements and Sr-Nd isotopes of foraminifera shell from the Okinawa Trough显示文摘Trace elemental associations and Sr-Nd isotopic compositions are of important to recognition of biogenic material from mixed marine sediments. The foraminifera shell from the Okinawa Trough strongly enriches Sr,P,Mn and Ba, enriches Li,U,Th,Sc,Co,Cu,Pb,Zn,Cr,Rb,Y,Sb and light rare earth elements,slightly enriches V,Ga,Zr,Nb,Cd and middle rare earth elements,is short of Mo,In,Sn,Cs,Hf,Ta,W,Ti,Bi and heavy rare earth elements. The mechanism of elemental enrichment in forminifera is the concentrations of trace elements in sea water and selective absorption of trace elements during foraminifera living, as well as the geochemical affinity between major elements and trace elements.The REE (rare earth elements)partition pattern of foraminifera shell of the Okinawa Trough shows enrichment of middle rare earth elements with slightly negative Ce anomaly,which are different from those of foraminifera of the Pacific Ocean.The Sr,Nd isotopic ratios of the Okinawa Trough foraminifera are 0 709 769 and 0 512 162,respectively, which are different not only from those of oceanic water, but also from those of river water of China’s Mainland, the former is slightly higher than those of oceanic water,but much lower than those of river water;the latter is slightly lower than those of oceanic water,but higher than those of river water,demonstrating that the Okinawa Trough sea water has been influenced by river water of China’s Mainland. | Meng Xianwei 1,2 ,Du Dewen 1,2 ,Cheng Zhenbo 11 .FirstInstituteofOceanography ,StateOceanicAdministration ,Qingdao 2 6 6 0 6 1,China2 .KeyLaboratoryofMarineScienceandNumericalModeling ,StateOceanicAdministration ,Qingdao 2 6 6 0 6 1,China | 2001 | Acta Oceanologica Sinica2001，20，1： | 4 |
| 5 | Retinal projection head-mounted display显示文摘 | Junguo LIN Dewen CHENG Cheng YAO Yongtian WANG | 2017 | Frontiers of Optoelectronics2017，10，1： | 4 |
| 6 | Iterative freeform lens design for prescribed irradiance on curved target显示文摘Current freeform illumination optical designs are mostly focused on producing prescribed irradiance distributions on planar targets.Here,we aim to design freeform optics that could generate a desired illumination on a curved target from a point source,which is still a challenge.We reduce the difficulties that arise from the curved target by involving its varying z-coordinates in the iterative wavefront tailoring(IWT)procedure.The new IWT-based method is developed under the stereographic coordinate system with a special mesh transformation of the source domain,which is suitable for light sources with light emissions in semi space such as LED sources.The first example demonstrates that a rectangular flat-top illumination can be generated on an undulating surface by a spherical-freeform lens for a Lambertian source.The second example shows that our method is also applicable for producing a non-uniform irradiance distribution in a circular region of the undulating surface. | Zexin Feng Dewen Cheng Yongtian Wang | 2020 | Opto-Electronic Advances2020，3，7： | 2 |
| 7 | Tide- and wind-driven variability of water level in Sansha Bay, Fujian, China显示文摘 | Hongyang LIN Jianyu HU Jia ZHU Peng CHENG Zhaozhang CHEN Zhenyu SUN Dewen CHEN | 2017 | Frontiers of Earth Science2017，11，2： | 2 |
| 8 | Design of an optical see-through head-mounted display with a low f-number and large field of view using a freeform prism显示文摘 | Dewen Cheng Yongtian Wang Hong Hua | 2009 | Proceedings of SPIE2009，5，： | 1 |
| 9 | Reservoir Quality and Diagenesis of the Permian Lucaogou Formation Tight Carbonates in Jimsar Sag, Junggar Basin, West China显示文摘The Lower Permian Lucaogou Formation in the Jimsar sag, Junggar Basin is a typical tight-oil reservoir in China. For effective exploration and production, the formation of a high-quality reservoir must be thoroughly studied. In this work, the tight-oil reservoir was examined using a variety of methods, including core and thin-section observations, XRD, SEM, CL and fluid inclusion and isotope testing. The tight-oil reservoirs were primarily deposited in saline lake environments, which are dominated by variable admixture of dolomite, quartz, feldspar, tuff, calcite and pyrite. Nine main lithofacies were identified:(1) siliceous mudstone,(2) dolomitic siliceous mudstone,(3) dolomitic mudstone,(4) intraclast packstone/grainstone,(5) ooid grainstone,(6) bioclast grainstone,(7) dolomitic siltstone,(8) mixed siliclastic and intraclast grainstone and(9) brecciated dolomitic mudstone. The pore types are classified into four categories: primary intergranular, moldic, intercrystalline and fracture pores. The properties of tight-oil reservoirs are quite poor, with low porosity(ave. 7.85%) and permeability(ave. 0.110 mD) and a small pore-throat radius(ave. 0.086 μm). The tight-oil reservoirs are dominated by the aggradation of a repetitive meter-scale sedimentary facies succession that records distinct lacustrine expansions and contractions. These tight carbonates have also undergone significant diagenetic alterations, such as dolomitization, dissolution, neomorphism and fracture created intercrystalline and moldic pores, vug and fractures; chemical and mechanical compaction and carbonate cementation have decreased the reservoir quality. Variations in reservoir quality in the Jimusar sag are due to a combination of lithofacies type, high-frequency cyclic depositional architecture, dissolution intensity, dolomitization and tectonic related deformation. This integrated study has helped in understanding the reservoir heterogeneity and hydrocarbon potential of the Jimusar fine-grained rocks. | Yongqiang Yang Longwei Qiu Yingchang Cao Cheng Chen Dewen Lei Ming Wan | 2017 | Journal of Earth Science2017，28，6： | 1 |
| 10 | Effect of radius mismatch on performance of segmented telescopic system 显示文摘 | CHENG Dewen WANG Yongtian Talha M M | 2007 | Proceedings of SPIE(S0277-786X)2007，6834，： | 1 |
| 11 | Effect of radius mismatch on performance of segmented telescopic systems显示文摘 | Cheng Dewen Wang Yongtian Talha M M | | 0，，： | 1 |
| 12 | De-sign of a compact wide field of view HMD optical system u-sing freeform surfaces 显示文摘 | TALHA M M WANG Yongtian CHENG Dewen | 2008 | SPIE2008，6624，： | 1 |
| 13 | Oral biomaterials for intestinal regulation显示文摘Intestinal diseases have always been a highly focused concern since recorded.Although endless efforts have been devoted,the underlying pathogenesis of alimentary canal disease remains mysterious and effective therapies are still in development.Intriguingly,the emerging of biomedical engineering has sprung up to unveil the enigmas of alimentary canal diseases,thus ameliorating the therapies and relieving the sufferings of patients.In this review,we present a comprehensive and deep-going perception into therapies of digestive disease with the assistance of biomaterials,involving the constructions of biomaterials and their mechanisms in digestive disease therapy.This review aims at conveying fundamentals of biomaterials in treating alimentary canal diseases,a critical analysis of their current applications and challenges,and a perspective on their future development.It is believed that this review will facilitate the communications between material science and medical fields. | Cheng Zhao Lijun Cai Hanxu Chen Hui Tan Dewen Yan | 2021 | Engineered Regeneration2021，2，1： | 1 |
| 14 | FreeformNet:fast and automatic generation of multiple-solution freeform imaging systems enabled by deep learning显示文摘Using freeform optical surfaces in lens design can lead to much higher system specifications and performance while significantly reducing volume and weight.However,because of the complexity of freeform surfaces,freeform optical design using traditional methods requires extensive human effort and sufficient design experience,while other design methods have limitations in design efficiency,simplicity,and versatility.Deep learning can solve these issues by summarizing design knowledge and applying it to design tasks with different system and structure parameters.We propose a deep-learning framework for designing freeform imaging systems.We generate the data set automatically using a combined sequential and random system evolution method.We combine supervised learning and unsupervised learning to train the network so that it has good generalization ability for a wide range of system and structure parameter values.The generated network FreeformNet enables fast generation(less than 0.003 s per system)of multiple-solution systems after we input the design requirements,including the system and structure parameters.We can filter and sort solutions based on a given criterion and use them as good starting points for quick final optimization(several seconds for systems with small or moderate field-of-view in general).The proposed framework presents a revolutionary approach to the lens design of freeform or generalized imaging systems,thus significantly reducing the time and effort expended on optical design. | BOYU MAO TONG YANG HUIMING XU WENCHEN CHEN DEWEN CHENG YONGTIAN WANG | 2023 | Photonics Research2023，11，8： | 0 |
| 15 | A kinematic model describing particle movement near a surface as effected by Brownian motion and electrostatic and Van der Waals forces显示文摘Nanoparticle movement near a surface is greatly influenced by electrostatic and Van der Waals forces between the particle and the surface,as well as by Brownian motion.In this paper,several precise equations are derived to describe the Van der Waals and electrostatic forces between a particle and a surface when the particle is removed from the surface.These include an equation for particle displacement under the electrostatic force,and a numerical calculation for particle displacement under the Van der Waals force.Finally,a kinematic model is constructed to describe the particle distribution under the effects of the electrostatic and Van der Waals forces,as well as the particle’s Brownian motion.The results show that increasing the multiply of the particle and surface zeta potential values and decreasing the ionic strength of the detergent can prevent a particle from redepositing onto a surface. | MEI HeGeng ZHAO DeWen WANG TongQin CHENG Jie LU XinChun | 2014 | Science China(Technological Sciences)2014，57，11： | 0 |
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