We have developed a self-contained,liquid tunable microlens based on polyacrylate membranes integrated with compact on-chip thermo-pneumatic actuation fabricated using full-wafer processing.Silicone oil is used as the...We have developed a self-contained,liquid tunable microlens based on polyacrylate membranes integrated with compact on-chip thermo-pneumatic actuation fabricated using full-wafer processing.Silicone oil is used as the optical liquid,which is pushed or pulled into the lens cavity via an extended microfluidic channel structure without any pumps,valves or other mechanical means.The heat load generated by the thermal actuator is physically isolated from the lens chamber.The back focal length may be tuned from infinity to 4 mm with a maximum power consumption of 300 mW.The principal application is fine tuning of the back focal length,for which tuning time constants as small as 100 ms are suitable.展开更多
Microbubbles acting as lenses are interesting for optical and photonic applications such as volumetric displays,optical resonators,integration of photonic components onto chips,high-resolution spectroscopy,lithography...Microbubbles acting as lenses are interesting for optical and photonic applications such as volumetric displays,optical resonators,integration of photonic components onto chips,high-resolution spectroscopy,lithography,and imaging.However,stable,rationally designed,and uniform microbubbles on substrates such as silicon chips are challenging because of the random nature of microbubble formation.We describe the fabrication of elastic microbubbles with a precise control of volume and curvature based on femtosecond laser irradiated graphene oxide.We demonstrate that the graphene microbubbles possess a near-perfect curvature that allows them to function as reflective microlenses for focusing broadband white light into an ultrahigh aspect ratio diffraction-limited photonic jet without chromatic aberration.Our results provide a pathway for integration of graphene microbubbles as lenses for nanophotonic components for miniaturized lab-on-a-chip devices along with applications in high-resolution spectroscopy and imaging.展开更多
Wafer-level mass production of photonic integrated circuits(PIC)has become a technological mainstay in the field of optics and photonics,enabling many novel and disrupting a wide range of existing applications.However...Wafer-level mass production of photonic integrated circuits(PIC)has become a technological mainstay in the field of optics and photonics,enabling many novel and disrupting a wide range of existing applications.However,scalable photonic packaging and system assembly still represents a major challenge that often hinders commercial adoption of PIC-based solutions.Specifically,chip-to-chip and fiber-to-chip connections often rely on so-called active alignment techniques,where the coupling efficiency is continuously measured and optimized during the assembly process.This unavoidably leads to technically complex assembly processes and high cost,thereby eliminating most of the inherent scalability advantages of PIC-based solutions.In this paper,we demonstrate that 3D-printed facet-attached microlenses(FaML)can overcome this problem by opening an attractive path towards highly scalable photonic system assembly,relying entirely on passive assembly techniques based on industry-standard machine vision and/or simple mechanical stops.FaML can be printed with high precision to the facets of optical components using multi-photon lithography,thereby offering the possibility to shape the emitted beams by freely designed refractive or reflective surfaces.Specifically,the emitted beams can be collimated to a comparatively large diameter that is independent of the device-specific mode fields,thereby relaxing both axial and lateral alignment tolerances.Moreover,the FaML concept allows to insert discrete optical elements such as optical isolators into the free-space beam paths between PIC facets.We show the viability and the versatility of the scheme in a series of selected experiments of high technical relevance,comprising pluggable fiber-chip interfaces,the combination of PIC with discrete micro-optical elements such as polarization beam splitters,as well as coupling with ultra-low back-reflection based on non-planar beam paths that only comprise tilted optical surfaces.Based on our results,we believe that the FaML concept opens an attractive path towards novel PIC-based system architectures that combine the distinct advantages of different photonic integration platforms.展开更多
his paper adopts the 3-3-2 information processing method for the capture of moving objects as its premise, and proposes a basic principle of three-dimensional (3D) imaging using biological compound eye. Traditional bi...his paper adopts the 3-3-2 information processing method for the capture of moving objects as its premise, and proposes a basic principle of three-dimensional (3D) imaging using biological compound eye. Traditional bionic vision is limited by the available hardware. Therefore, in this paper, the new-generation technology of microlens-array light-field camera is proposed as a potential method for the extraction of depth information from a single image. A significant characteristic of light-field imaging is that it records intensity and directional information from the lights entering the camera. Herein, a refocusing method using light-field image is proposed. By calculating the focusing cost at different depths from the object, the imaging plane of the object is determined, and a depth map is constructed based on the position of the object’s imaging plane. Compared with traditional light-field depth estimation, the depth map calculated by this method can significantly improve resolution and does not depend on the number of light-field microlenses. In addition, considering that software algorithms rely on hardware structure, this study develops an imaging hardware that is only 7 cm long based on the second-generation microlens camera’s structure, further validating its important refocusing characteristics. It thereby provides a technical foundation for 3D imaging with a single camera.展开更多
This review focuses on recent developments in additive manufacturing(AM)of precision optical devices,particularly devices consisting of components with critical features at the micro-and nanoscale.These include,but ar...This review focuses on recent developments in additive manufacturing(AM)of precision optical devices,particularly devices consisting of components with critical features at the micro-and nanoscale.These include,but are not limited to,microlenses,diffractive optical elements,and photonic devices.However,optical devices with large-size lenses and mirrors are not specifically included as this technology has not demonstrated feasibilities in that category.The review is roughly divided into two slightly separated topics,the first on meso-and microoptics and the second on optics with nanoscale features.Although AM of precision optics is still in its infancy with many unanswered questions,the references cited on this exciting topic demonstrate an enabling technology with almost unlimited possibilities.There are many high quality reviews of AM processes of non-optical components,hence they are not the focus of this review.The main purpose of this review is to start a conversion on optical fabrication based on information about 3D AM methods that has been made available to date,with an ultimate long-term goal of establishing new optical manufacturing methods that are low cost and highly precise with extreme flexibility.展开更多
Microlens arrays are the key component in the next generation of 3D imaging system, for it exhibits some good optical properties such as extremely large field of view angles, low aberration and distortion, high tempor...Microlens arrays are the key component in the next generation of 3D imaging system, for it exhibits some good optical properties such as extremely large field of view angles, low aberration and distortion, high temporal resolution and infinite depth of field. Although many fabrication methods or processes are proposed for manufacturing such precision component, however, those methods still need to be improved. In this review, those fabrication methods are categorized into direct and indirect method and compared in detail. Two main challenges in manufacturing microlens array are identified: how to obtain a microlens array with good uniformity in a large area and how to produce the microlens array on a curved surface? In order to effectively achieve control of the geometry of a microlens,indirect methods involving the use of 3D molds and replication technologies are suggested. Further development of ultraprecision machining technology is needed to reduce the surface fluctuation by considering the dynamics of machine tool in tool path planning. Finally, the challenges and opportunities of manufacturing microlens array in industry and academic research are discussed and several principle conclusions are drawn.展开更多
Although femtosecond laser microfabrication is one of the most promising three-dimensional(3D) fabrication techniques, it could suffer from low fabrication efficiency for structures with high 3D complexities. By usi...Although femtosecond laser microfabrication is one of the most promising three-dimensional(3D) fabrication techniques, it could suffer from low fabrication efficiency for structures with high 3D complexities. By using etching as a main assistant technique, the processing can be speeded up and an improved structure surface quality can be provided. However,the assistance of a single technique cannot satisfy the increasing demands of fabrication and integration of highly functional 3D microstructures. Therefore, a multi-technique-based 3D microfabrication method is required. In this paper, we briefly review the recent development on etching-assisted femtosecond laser microfabrication(EAFLM). Various processing approaches have been proposed to further strengthen the flexibilities of the EAFLM. With the use of the multi-technique-based microfabrication method, 3D microstructure arrays can be rapidly defined on planar or curved surfaces with high structure qualities.展开更多
Multifocal multiphoton microscopy(MMM)has recently become an important tool in biomedicine for performing three-dimensional fastfluorescence imaging.Using various beamsplitting techniques,MMM splits the near-infrared ...Multifocal multiphoton microscopy(MMM)has recently become an important tool in biomedicine for performing three-dimensional fastfluorescence imaging.Using various beamsplitting techniques,MMM splits the near-infrared laser beam into multiple beamlets and produces a multifocal array on the sample for parallel multiphoton excitation and then recordsfluorescence signal from all foci simultaneously with an area array detector,which significantly improves the imaging speed of multiphoton microscopy and allows for high efficiency in use of the excitation light.In this paper,we discuss the features of several MMM setups using different beamsplitting devices,including a Nipkow spinning disk,a microlens array,a set of beamsplitting mirrors,or a diffractive optical element(DOE).In particular,we present our recent work on the development of an MMM using a spatial light modulator(SLM).展开更多
The structure of a microlens array( MLA) can be formed on copper by an indentation process which is a new manufacture approach we applied here instead of a traditional method to test the material property,thereby wo...The structure of a microlens array( MLA) can be formed on copper by an indentation process which is a new manufacture approach we applied here instead of a traditional method to test the material property,thereby work time can be saved. Single-indentation and multi-indentation are both conducted to generate a single dimple and dimples array,namely micro lens and MLA. Based on finite element simulation method,factors affecting the form accuracy,such as springback at the compressed area of one single dimple and compressional deformation at the adjacent area of dimples arrays,are determined,and the results are verified by experiments under the same conditions. Meanwhile,indenter compensation method is proposed to improve form accuracy of single dimple,and the relationship between pitch and compressional deformation is investigated by modelling seven sets of multi-indentations at different pitches to identify the critical pitch for the MLA's indentation processing. Loads and cross-sectional profiles are measured and analyzed to reveal the compressional deformation mechanism. Finally,it is found that MLA at pitches higher than 1. 47 times of its diameter can be manufactured precisely by indentation using a compensated indenter.展开更多
An intense supercontinuum(SC) in the near-ultraviolet range is generated from filamentation by focusing a 400-nm laser into fused silica with a microlens array(MLA). The spectrum of the SC is shown to be sensitive...An intense supercontinuum(SC) in the near-ultraviolet range is generated from filamentation by focusing a 400-nm laser into fused silica with a microlens array(MLA). The spectrum of the SC is shown to be sensitive to the distance between the MLA and fused silica. In our optimal conditions, the near-ultraviolet SC can cover a range of 350-600 nm,where a bandwidth of approximately 55 nm above the 1μJ/nm spectral energy density and 20 nm bandwidth with tens ofμJ/nm are achieved. In addition, the energy conversion efficiency of the 400 nm laser for SC generation is further analyzed.A maximum conversion efficiency of 66% is obtained when the entrance face of fused silica is set around the focus of the MLA.展开更多
High power supercontinuum(SC) is generated by focusing 800 nm and 400 nm femtosecond laser pulses in fused silica with a microlens array. It is found that the spectrum of the SC is getting broader compared with the ca...High power supercontinuum(SC) is generated by focusing 800 nm and 400 nm femtosecond laser pulses in fused silica with a microlens array. It is found that the spectrum of the SC is getting broader compared with the case of a single laser pulse, and the spectral energy density between the two fundamental laser wavelengths is getting significantly higher by optimizing the phase matching angle of the BBO. It exceeds μJ/nm over 490 nm range which is from 380 nm to 870 nm,overcoming the disadvantage of relative lower power in the ranges far from the fundamental wavelength.展开更多
A further study on the fabrication of diffraction--limited full aperture microlens array by melting photoresist is described. The formation of aspherical surface is considered. The parameters for controlling the proce...A further study on the fabrication of diffraction--limited full aperture microlens array by melting photoresist is described. The formation of aspherical surface is considered. The parameters for controlling the process of lens production, the height of original photoresist cylinders and the angle of contact between the melted photoresist and the substrate, are discussed in detail. The diffraction limited full--aperture microlens arrays have been obtained,and some measurement results are shown in the paper. A method of controlling the formation of quality microlens array in real time is suggested.展开更多
This paper describes the formation technology of polymeric microlenses self-organized on the fiber top in the limited reaction volume. The loss inserted to the optical coupling channel and their sources was investigated.
Unlike the luminous objects observed, dark matter does not emit light but can be only detected by its gravitational effect. Modern cosmology considers that most matter in Universe is dark matter. However, it is still ...Unlike the luminous objects observed, dark matter does not emit light but can be only detected by its gravitational effect. Modern cosmology considers that most matter in Universe is dark matter. However, it is still not clear what the dark matter was. Two origins have been proposed by astrophysicists, astrophysics candidates and particle physics candidates. The most differences are their morphology, the former are compact objects and the latter are dispersed. Under Einstein</span><span style="font-family:Verdana;">’</span><span style="font-family:""><span style="font-family:Verdana;">s theory of general relativity, light bends as it passes near a compact object, creating a convergence effect like a lens. When background light source, intervening lense and the observer lie on a straight line, the brightness of the background source will be significantly magnified. In astrophysics, this effect is called microlensing. If compact dark matter is abundant in the universe, it is possible to frequently observe “microlensing” events when observing high redshift objects, </span><i><span style="font-family:Verdana;">i.e.</span></i><span style="font-family:Verdana;"> the objects temporarily brighten for a certain time. The microlensing technique has been applied to study the dark matter in halo of Milky Way. The difficulty occurs when applying to study the cosmic dark matter as the crossing time of cosmic microlensing events </span></span><span style="font-family:Verdana;">is</span><span style="font-family:Verdana;"> too long for observations. Apparent superluminal jets in bright quasars are idea background objects, significantly enhancing the efficiency of cosmic microlensing survey. Here, we tentatively designed an observational experiment to study the morphology of dark matter in Universe via statistics of microlensing events towards luminous quasars with apparent superluminal jets.展开更多
Compared with the traditional scanning confocal microscopy, the effect of various factors on characteristic in multi-beam parallel confocal system is discussed, the error factors in multi-beam parallel confocal system...Compared with the traditional scanning confocal microscopy, the effect of various factors on characteristic in multi-beam parallel confocal system is discussed, the error factors in multi-beam parallel confocal system are analyzed. The factors influencing the characteristics of the multi-beam parallel confocal system are discussed. The construction and working principle of the non-scanning 3D detecting system is introduced, and some experiment results prove the effect of various factors on the detecting system.展开更多
The principal testing ground for general relativity is the observable Universe. Gravitational lensing is the leading observational technique that gives insight into the distribution of baryonic matter in the stellar, ...The principal testing ground for general relativity is the observable Universe. Gravitational lensing is the leading observational technique that gives insight into the distribution of baryonic matter in the stellar, galactic and cosmological scale, as well as the distribution of dark matter and dark energy, due to their gravitational interaction. Interpretation of ever more precise observational data requires increasingly subtle analytical techniques. In this paper, I discuss a formalism that can handle a nonlinear superposition of gravitational and refractive lensing by a grouping of baryonic matter, dark matter and dark energy for a given distribution of those entities (i.e. for a given spacetime metric) and their refractive properties. The role of refraction in gravitational lensing is exemplified in the case of a microlensing event and a signature of such an effect is discussed.展开更多
Metalenses with achromatic performance offer a new opportunity for high-quality imaging with an ultracompact configuration;however,they suffer from complex fabrication processes and low focusing efficiency.In this stu...Metalenses with achromatic performance offer a new opportunity for high-quality imaging with an ultracompact configuration;however,they suffer from complex fabrication processes and low focusing efficiency.In this study,we propose an efficient design method for achromatic microlenses on a wavelength scale using materials with low dispersion,an adequately designed convex surface,and a thickness profile distribution.By taking into account the absolute chromatic aberration,relative focal length shift(FLS),and numerical aperture(NA),microlens with a certain focal length can be realized through our realized map of geometric features.Accordingly,the designed achromatic microlenses with low-dispersion fused silica were fabricated using a focused ion beam,and precise surface profiles were obtained.The fabricated microlenses exhibited a high average focusing efficiency of 65%at visible wavelengths of 410-680 nm and excellent achromatic capability via white light imaging.Moreover,the design exhibited the advantages of being polarization-insensitive and near-diffraction-limited.These results demonstrate the effectiveness of our proposed achromatic microlens design approach,which expands the prospects of miniaturized optics such as virtual and augmented reality,ultracompact microscopes,and biological endoscopy.展开更多
Piezoresistive composite elastomers have shown great potentials for wearable and flexible electronic applications due to their high sensitivity,excellent frequency response,and easy signal detection.A composition memb...Piezoresistive composite elastomers have shown great potentials for wearable and flexible electronic applications due to their high sensitivity,excellent frequency response,and easy signal detection.A composition membrane sensor with an interlocked structure has been developed and demonstrated outstanding pressure sensitivity,fast response time,and low temperature drift features.Compared with a flexible MXene-based flat sensor(Ti_(3)C_(2)),the interlocked sensor exhibits a significantly improved pressure sensitivity of two magnitudes higher(21.04 kPa^(-1)),a fast reaction speed of 31 ms,and an excellent cycle life of 5000 test runs.The viability of sensor in responding to various external stimuli with high deformation capacity has been confirmed by calculating the force distribution of a polydimethylsiloxane(PDMS)film model with a microlens structure using the solid mechanics module in COMSOL.Unlike conventional process,we utilized three-dimensional(3D)laser-direct writing lithography equipment to directly transform high-precision 3D data into a micro-nano structure morphology through variable exposure doses,which reduces the hot melting step.Moreover,the flexible pressure device is capable of detecting and distinguishing signals ranging from finger movements to human pulses,even for speech recognition.This simple,convenient,and large-format lithographic method offers new opportunities for developing novel human-computer interaction devices.展开更多
文摘We have developed a self-contained,liquid tunable microlens based on polyacrylate membranes integrated with compact on-chip thermo-pneumatic actuation fabricated using full-wafer processing.Silicone oil is used as the optical liquid,which is pushed or pulled into the lens cavity via an extended microfluidic channel structure without any pumps,valves or other mechanical means.The heat load generated by the thermal actuator is physically isolated from the lens chamber.The back focal length may be tuned from infinity to 4 mm with a maximum power consumption of 300 mW.The principal application is fine tuning of the back focal length,for which tuning time constants as small as 100 ms are suitable.
基金the Australian Research Council for its support(Nos.DP150102972,DP190103186,and IC180100005)the National Research Foundation of Singapore for its support(No.NRF-RP15-2015-04)the financial support from the Australian Research Council(No.FL180100029)
文摘Microbubbles acting as lenses are interesting for optical and photonic applications such as volumetric displays,optical resonators,integration of photonic components onto chips,high-resolution spectroscopy,lithography,and imaging.However,stable,rationally designed,and uniform microbubbles on substrates such as silicon chips are challenging because of the random nature of microbubble formation.We describe the fabrication of elastic microbubbles with a precise control of volume and curvature based on femtosecond laser irradiated graphene oxide.We demonstrate that the graphene microbubbles possess a near-perfect curvature that allows them to function as reflective microlenses for focusing broadband white light into an ultrahigh aspect ratio diffraction-limited photonic jet without chromatic aberration.Our results provide a pathway for integration of graphene microbubbles as lenses for nanophotonic components for miniaturized lab-on-a-chip devices along with applications in high-resolution spectroscopy and imaging.
基金the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)under Germany’s Excellence Strategy via the Excellence Cluster 3D Matter Made to Order(EXC-2082/1-390761711)the Collaborative Research Center WavePhenomena(CRC 1173)+4 种基金by the Bundesministerium für Bildung und Forschung(BMBF)via the projects PRIMA(#13N14630),DiFeMiS(#16ES0948)which is part of the programme“Forschungslabore Mikroelektronik Deutschland(ForLab),and Open6GHub(#16KISK010)by the European Research Council(ERC Consolidator Grant‘TeraSHAPE’#773248),by the H2020 Photonic Packaging Pilot Line PIXAPP(#731954)by the Alfried Krupp von Bohlen und Halbach Foundation,and by the Karlsruhe School of Optics and Photonics(KSOP).
文摘Wafer-level mass production of photonic integrated circuits(PIC)has become a technological mainstay in the field of optics and photonics,enabling many novel and disrupting a wide range of existing applications.However,scalable photonic packaging and system assembly still represents a major challenge that often hinders commercial adoption of PIC-based solutions.Specifically,chip-to-chip and fiber-to-chip connections often rely on so-called active alignment techniques,where the coupling efficiency is continuously measured and optimized during the assembly process.This unavoidably leads to technically complex assembly processes and high cost,thereby eliminating most of the inherent scalability advantages of PIC-based solutions.In this paper,we demonstrate that 3D-printed facet-attached microlenses(FaML)can overcome this problem by opening an attractive path towards highly scalable photonic system assembly,relying entirely on passive assembly techniques based on industry-standard machine vision and/or simple mechanical stops.FaML can be printed with high precision to the facets of optical components using multi-photon lithography,thereby offering the possibility to shape the emitted beams by freely designed refractive or reflective surfaces.Specifically,the emitted beams can be collimated to a comparatively large diameter that is independent of the device-specific mode fields,thereby relaxing both axial and lateral alignment tolerances.Moreover,the FaML concept allows to insert discrete optical elements such as optical isolators into the free-space beam paths between PIC facets.We show the viability and the versatility of the scheme in a series of selected experiments of high technical relevance,comprising pluggable fiber-chip interfaces,the combination of PIC with discrete micro-optical elements such as polarization beam splitters,as well as coupling with ultra-low back-reflection based on non-planar beam paths that only comprise tilted optical surfaces.Based on our results,we believe that the FaML concept opens an attractive path towards novel PIC-based system architectures that combine the distinct advantages of different photonic integration platforms.
基金The National Major Project Research and Development Project (2017YFB0503003)The National Natural Science Foundation of China(61101157, 60602042).
文摘his paper adopts the 3-3-2 information processing method for the capture of moving objects as its premise, and proposes a basic principle of three-dimensional (3D) imaging using biological compound eye. Traditional bionic vision is limited by the available hardware. Therefore, in this paper, the new-generation technology of microlens-array light-field camera is proposed as a potential method for the extraction of depth information from a single image. A significant characteristic of light-field imaging is that it records intensity and directional information from the lights entering the camera. Herein, a refocusing method using light-field image is proposed. By calculating the focusing cost at different depths from the object, the imaging plane of the object is determined, and a depth map is constructed based on the position of the object’s imaging plane. Compared with traditional light-field depth estimation, the depth map calculated by this method can significantly improve resolution and does not depend on the number of light-field microlenses. In addition, considering that software algorithms rely on hardware structure, this study develops an imaging hardware that is only 7 cm long based on the second-generation microlens camera’s structure, further validating its important refocusing characteristics. It thereby provides a technical foundation for 3D imaging with a single camera.
文摘This review focuses on recent developments in additive manufacturing(AM)of precision optical devices,particularly devices consisting of components with critical features at the micro-and nanoscale.These include,but are not limited to,microlenses,diffractive optical elements,and photonic devices.However,optical devices with large-size lenses and mirrors are not specifically included as this technology has not demonstrated feasibilities in that category.The review is roughly divided into two slightly separated topics,the first on meso-and microoptics and the second on optics with nanoscale features.Although AM of precision optics is still in its infancy with many unanswered questions,the references cited on this exciting topic demonstrate an enabling technology with almost unlimited possibilities.There are many high quality reviews of AM processes of non-optical components,hence they are not the focus of this review.The main purpose of this review is to start a conversion on optical fabrication based on information about 3D AM methods that has been made available to date,with an ultimate long-term goal of establishing new optical manufacturing methods that are low cost and highly precise with extreme flexibility.
基金Supported by Shenzhen Science,Technology and Innovation Commission of China(Grant No.JCYJ20150630115257902)the Research Grants Council of the Hong Kong Special Administrative Region of China(Grant No.ITS/339/13FX)Research Committee of The Hong Kong Polytechnic University,China (Grant No.RUK0)
文摘Microlens arrays are the key component in the next generation of 3D imaging system, for it exhibits some good optical properties such as extremely large field of view angles, low aberration and distortion, high temporal resolution and infinite depth of field. Although many fabrication methods or processes are proposed for manufacturing such precision component, however, those methods still need to be improved. In this review, those fabrication methods are categorized into direct and indirect method and compared in detail. Two main challenges in manufacturing microlens array are identified: how to obtain a microlens array with good uniformity in a large area and how to produce the microlens array on a curved surface? In order to effectively achieve control of the geometry of a microlens,indirect methods involving the use of 3D molds and replication technologies are suggested. Further development of ultraprecision machining technology is needed to reduce the surface fluctuation by considering the dynamics of machine tool in tool path planning. Finally, the challenges and opportunities of manufacturing microlens array in industry and academic research are discussed and several principle conclusions are drawn.
基金Project supported by the National Natural Science Foundation of China(Grant No.51501070)
文摘Although femtosecond laser microfabrication is one of the most promising three-dimensional(3D) fabrication techniques, it could suffer from low fabrication efficiency for structures with high 3D complexities. By using etching as a main assistant technique, the processing can be speeded up and an improved structure surface quality can be provided. However,the assistance of a single technique cannot satisfy the increasing demands of fabrication and integration of highly functional 3D microstructures. Therefore, a multi-technique-based 3D microfabrication method is required. In this paper, we briefly review the recent development on etching-assisted femtosecond laser microfabrication(EAFLM). Various processing approaches have been proposed to further strengthen the flexibilities of the EAFLM. With the use of the multi-technique-based microfabrication method, 3D microstructure arrays can be rapidly defined on planar or curved surfaces with high structure qualities.
基金This work has been partially supported by NIH(SC COBRE P20RR021949 and Career Award 1k25hl088262-01)NSF(MRI CBET-0923311 and SC EPSCoR RII EPS-0903795 through SC GEAR program)+3 种基金The National Natural Science Foundation of China(31171372,61078067)Guangdong Province Science and Technology Project(2010B060300002)Shenzhen University Application Technology Development Project(201136,CXB201104220021A,JC201005250032A,200854)the Fundamental Research Funds for the Central Universities(K50510050006).
文摘Multifocal multiphoton microscopy(MMM)has recently become an important tool in biomedicine for performing three-dimensional fastfluorescence imaging.Using various beamsplitting techniques,MMM splits the near-infrared laser beam into multiple beamlets and produces a multifocal array on the sample for parallel multiphoton excitation and then recordsfluorescence signal from all foci simultaneously with an area array detector,which significantly improves the imaging speed of multiphoton microscopy and allows for high efficiency in use of the excitation light.In this paper,we discuss the features of several MMM setups using different beamsplitting devices,including a Nipkow spinning disk,a microlens array,a set of beamsplitting mirrors,or a diffractive optical element(DOE).In particular,we present our recent work on the development of an MMM using a spatial light modulator(SLM).
基金Supported by the National Natural Science Foundation of China(51375050)
文摘The structure of a microlens array( MLA) can be formed on copper by an indentation process which is a new manufacture approach we applied here instead of a traditional method to test the material property,thereby work time can be saved. Single-indentation and multi-indentation are both conducted to generate a single dimple and dimples array,namely micro lens and MLA. Based on finite element simulation method,factors affecting the form accuracy,such as springback at the compressed area of one single dimple and compressional deformation at the adjacent area of dimples arrays,are determined,and the results are verified by experiments under the same conditions. Meanwhile,indenter compensation method is proposed to improve form accuracy of single dimple,and the relationship between pitch and compressional deformation is investigated by modelling seven sets of multi-indentations at different pitches to identify the critical pitch for the MLA's indentation processing. Loads and cross-sectional profiles are measured and analyzed to reveal the compressional deformation mechanism. Finally,it is found that MLA at pitches higher than 1. 47 times of its diameter can be manufactured precisely by indentation using a compensated indenter.
基金Project supported by the National Basic Research Program of China(Grant No.2013CB922404)the National Natural Science Foundation of China(Grant Nos.11274053,11474039,11474040,and 11004240)+1 种基金the Science and Technology Department of Jilin Province,China(Grant No.20170519018JH)the Innovation Fund of Changchun University of Science and Technology,China(Grant No.XJJLG-2016-02)
文摘An intense supercontinuum(SC) in the near-ultraviolet range is generated from filamentation by focusing a 400-nm laser into fused silica with a microlens array(MLA). The spectrum of the SC is shown to be sensitive to the distance between the MLA and fused silica. In our optimal conditions, the near-ultraviolet SC can cover a range of 350-600 nm,where a bandwidth of approximately 55 nm above the 1μJ/nm spectral energy density and 20 nm bandwidth with tens ofμJ/nm are achieved. In addition, the energy conversion efficiency of the 400 nm laser for SC generation is further analyzed.A maximum conversion efficiency of 66% is obtained when the entrance face of fused silica is set around the focus of the MLA.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12074228,11774038,and 11474039)the Taishan Scholar Project of Shandong Province,China(Grant No.tsqn201812043)+1 种基金Natural Science Foundation of Shandong Province,China(Grant No.ZR2021MA023)the Innovation Group of Jinan(Grant No.2020GXRC039)。
文摘High power supercontinuum(SC) is generated by focusing 800 nm and 400 nm femtosecond laser pulses in fused silica with a microlens array. It is found that the spectrum of the SC is getting broader compared with the case of a single laser pulse, and the spectral energy density between the two fundamental laser wavelengths is getting significantly higher by optimizing the phase matching angle of the BBO. It exceeds μJ/nm over 490 nm range which is from 380 nm to 870 nm,overcoming the disadvantage of relative lower power in the ranges far from the fundamental wavelength.
文摘A further study on the fabrication of diffraction--limited full aperture microlens array by melting photoresist is described. The formation of aspherical surface is considered. The parameters for controlling the process of lens production, the height of original photoresist cylinders and the angle of contact between the melted photoresist and the substrate, are discussed in detail. The diffraction limited full--aperture microlens arrays have been obtained,and some measurement results are shown in the paper. A method of controlling the formation of quality microlens array in real time is suggested.
文摘This paper describes the formation technology of polymeric microlenses self-organized on the fiber top in the limited reaction volume. The loss inserted to the optical coupling channel and their sources was investigated.
文摘Unlike the luminous objects observed, dark matter does not emit light but can be only detected by its gravitational effect. Modern cosmology considers that most matter in Universe is dark matter. However, it is still not clear what the dark matter was. Two origins have been proposed by astrophysicists, astrophysics candidates and particle physics candidates. The most differences are their morphology, the former are compact objects and the latter are dispersed. Under Einstein</span><span style="font-family:Verdana;">’</span><span style="font-family:""><span style="font-family:Verdana;">s theory of general relativity, light bends as it passes near a compact object, creating a convergence effect like a lens. When background light source, intervening lense and the observer lie on a straight line, the brightness of the background source will be significantly magnified. In astrophysics, this effect is called microlensing. If compact dark matter is abundant in the universe, it is possible to frequently observe “microlensing” events when observing high redshift objects, </span><i><span style="font-family:Verdana;">i.e.</span></i><span style="font-family:Verdana;"> the objects temporarily brighten for a certain time. The microlensing technique has been applied to study the dark matter in halo of Milky Way. The difficulty occurs when applying to study the cosmic dark matter as the crossing time of cosmic microlensing events </span></span><span style="font-family:Verdana;">is</span><span style="font-family:Verdana;"> too long for observations. Apparent superluminal jets in bright quasars are idea background objects, significantly enhancing the efficiency of cosmic microlensing survey. Here, we tentatively designed an observational experiment to study the morphology of dark matter in Universe via statistics of microlensing events towards luminous quasars with apparent superluminal jets.
基金This project is supported by National Natural Science Foundation of China (No.50175024)Provincial Program for Young Teacher of Colleges and Universities of Anhui(No.2005jql019)Provincial Research Foundation of Key Laboratory of Anhui.
文摘Compared with the traditional scanning confocal microscopy, the effect of various factors on characteristic in multi-beam parallel confocal system is discussed, the error factors in multi-beam parallel confocal system are analyzed. The factors influencing the characteristics of the multi-beam parallel confocal system are discussed. The construction and working principle of the non-scanning 3D detecting system is introduced, and some experiment results prove the effect of various factors on the detecting system.
文摘The principal testing ground for general relativity is the observable Universe. Gravitational lensing is the leading observational technique that gives insight into the distribution of baryonic matter in the stellar, galactic and cosmological scale, as well as the distribution of dark matter and dark energy, due to their gravitational interaction. Interpretation of ever more precise observational data requires increasingly subtle analytical techniques. In this paper, I discuss a formalism that can handle a nonlinear superposition of gravitational and refractive lensing by a grouping of baryonic matter, dark matter and dark energy for a given distribution of those entities (i.e. for a given spacetime metric) and their refractive properties. The role of refraction in gravitational lensing is exemplified in the case of a microlensing event and a signature of such an effect is discussed.
基金supported by grants from the National Key Research and Development Program of China(2022YFB3806000)the National Natural Science Foundation of China(52325208 and 11974203)the Beijing Municipal Science and Technology Project(Z191100004819002).
文摘Metalenses with achromatic performance offer a new opportunity for high-quality imaging with an ultracompact configuration;however,they suffer from complex fabrication processes and low focusing efficiency.In this study,we propose an efficient design method for achromatic microlenses on a wavelength scale using materials with low dispersion,an adequately designed convex surface,and a thickness profile distribution.By taking into account the absolute chromatic aberration,relative focal length shift(FLS),and numerical aperture(NA),microlens with a certain focal length can be realized through our realized map of geometric features.Accordingly,the designed achromatic microlenses with low-dispersion fused silica were fabricated using a focused ion beam,and precise surface profiles were obtained.The fabricated microlenses exhibited a high average focusing efficiency of 65%at visible wavelengths of 410-680 nm and excellent achromatic capability via white light imaging.Moreover,the design exhibited the advantages of being polarization-insensitive and near-diffraction-limited.These results demonstrate the effectiveness of our proposed achromatic microlens design approach,which expands the prospects of miniaturized optics such as virtual and augmented reality,ultracompact microscopes,and biological endoscopy.
基金This work was supported by the National Natural Science Foundation of China(No.61974100)the National Science Foundation of the Jiangsu Higher Education Institutions of China(No.20KJA480002)+2 种基金This project was also funded by the Collaborative Innovation Center of Suzhou Nano Science and Technology,and by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)X.H.Z.acknowledges the support from the NSERC-Alberta Innovated Advanced Program.B.B.X.and Y.H.J.are grateful for the support from the Engineering and Physical Sciences Research Council(EPSRC,UK)(Nos.EP/N007921 and EP/X02041X)Y.H.J.also acknowledges the support from the Leverhulme Trust(No.RPG-2022-177).
文摘Piezoresistive composite elastomers have shown great potentials for wearable and flexible electronic applications due to their high sensitivity,excellent frequency response,and easy signal detection.A composition membrane sensor with an interlocked structure has been developed and demonstrated outstanding pressure sensitivity,fast response time,and low temperature drift features.Compared with a flexible MXene-based flat sensor(Ti_(3)C_(2)),the interlocked sensor exhibits a significantly improved pressure sensitivity of two magnitudes higher(21.04 kPa^(-1)),a fast reaction speed of 31 ms,and an excellent cycle life of 5000 test runs.The viability of sensor in responding to various external stimuli with high deformation capacity has been confirmed by calculating the force distribution of a polydimethylsiloxane(PDMS)film model with a microlens structure using the solid mechanics module in COMSOL.Unlike conventional process,we utilized three-dimensional(3D)laser-direct writing lithography equipment to directly transform high-precision 3D data into a micro-nano structure morphology through variable exposure doses,which reduces the hot melting step.Moreover,the flexible pressure device is capable of detecting and distinguishing signals ranging from finger movements to human pulses,even for speech recognition.This simple,convenient,and large-format lithographic method offers new opportunities for developing novel human-computer interaction devices.