Lanthanum-bearing iron lithium borate glass is a quaternary system for oxide glasses and was prepared via the melt-quenching method.The present article correlates the structure,optical,ligand field and M?ssbauer data ...Lanthanum-bearing iron lithium borate glass is a quaternary system for oxide glasses and was prepared via the melt-quenching method.The present article correlates the structure,optical,ligand field and M?ssbauer data on iron lithium borate glass co ntaining La^(3+).The density was measured,while the molar volume was calculated.Other physical parameters are well-described.With increasing the La_(2)O_(3) content within the glass network,infrared spectra analysis reveals structural modifications such as the increase in BO_(4) units and the decline in both BO_(3) units and NBO bonds content.Furthermore,optical absorption spectra were measured.The absorption spectra disclose a plethora of electronic transitions that are related to Fe^(3+)in tetrahedral and octahedral sites,however,Fe^(2+)phase is not observed in optical spectra,but it has a clear signature in M?ssbauer spectra.Besides,the glass absorption edges undergo a clear blue shift,reflecting an increased band gap energy(1.96-2.28 eV).The decline in NBO bonds justifies this trend.Bewitchingly,the values of crystal field splitting are increased,while the values of Racah parameters are decreased.This trend is justified by the decline in NBO bonds and increases electron localization around Fe cations.M?ssbauer spectra confirm the existence of Fe^(3+)in tetrahedral and octahedral sites,while Fe^(2+)exists in only a tetrahedral state.With increasing La_(2)O_(3) content,the isomer shift of Fe^(3+)in tetrahedral sites changes to be 0.312-0.329 mm/s,while the isomer shift of octahedral Fe^(3+)is 0.424-0.456 mm/s.These findings coincide with optical data.While the isomer shift of tetrahedral Fe^(2+)is 0.902-0.911 mm/s.Our results of structural,optical and ligand field associated with M?ssbauer spectra open more vistas toward the utility of these samples in the optics realm.展开更多
Purpose:To examine the changes in choroidal thickness(ChT)after 6-month topical treatment of 0.01%atropine eye drops in myopic children.Methods:A total of 46 low to moderate myopic children aged 8 to 12 years were rec...Purpose:To examine the changes in choroidal thickness(ChT)after 6-month topical treatment of 0.01%atropine eye drops in myopic children.Methods:A total of 46 low to moderate myopic children aged 8 to 12 years were recruited and received topical 0.01%atropine once a day for 6 months.Spherical equivalent(SE),axial length(AL),and ChT were measured at baseline,3 months,and 6 months.Results:During the first and second 3-month treatment,there is no significant decrease in progression of SE and AL.Within the range of 3 mm from the temporal side of the fovea to the nasal side,no significant changes in ChT have been observed at any measuring points in low and moderate myopic participants.Changes in ChT were not significantly associated with gender or AL progression.Conclusion:A 6-month topical treatment of 0.01%atropine could not cause significant changes in ChT in myopic children.展开更多
Near-infrared(NIR) nanoparticles(NPs) based on fluorescence resonance energy transfer(FRET) were prepared by coencapsulation of a red aggregation-induced emission(AIE) molecule, 2-(4-bromophenyl)-3-(4-(4-(diphenylamin...Near-infrared(NIR) nanoparticles(NPs) based on fluorescence resonance energy transfer(FRET) were prepared by coencapsulation of a red aggregation-induced emission(AIE) molecule, 2-(4-bromophenyl)-3-(4-(4-(diphenylamino)styryl)phenyl)fumaronitrile(TB), and a commercial NIR fluorescence dye, silicon 2,3-naphthalocyanine bis(trihexylsilyloxide)(NIR775) with an amphiphilic polymer poly(styrene-co-maleic anhydride)(PSMA). The surface of the NPs, PSMA@TB/NIR775, was modified with poly(ethylene glycol)(PEG) to increase the in vivo biocompatibility of the NPs. The PSMA@TB/NIR775 NPs showed a strong NIR(780 nm) narrow emission and excellent two-photon absorption property. Moreover, the NPs exhibited good monodispersity, stability, and low cytotoxicity.Under the excitation of a 1040 nm femtosecond(fs) laser, the emission peaks at 680 nm of TB and 780 nm of NIR775 excited by FRET were obtained. We utilized PSMA@TB/NIR775 NPs as fluorescent contrast agents for two-photon excited NIR microscopic imaging, and good NIR imaging effect of mouse brain vasculature was obtained with the imaging depth of about 150 μm. The FRET strategy by coencapsulating AIE molecule and NIR dye will be helpful in preparing more narrow emission NIR probes for deep-tissue biological imaging.展开更多
The separation between s- and p-polarization components invariably affects thin film edge filters used for tilted incidence and is a difficult problem for many applications, especially for optical communication. This ...The separation between s- and p-polarization components invariably affects thin film edge filters used for tilted incidence and is a difficult problem for many applications, especially for optical communication. This paper presents a novel design method to obtain edge filters with non-polarization at incidence angle of 45°. The polarization separation at 50% trans-mittance for a long-wave-pass filter and a short-wave-pass filter is 0.3 nm and 0.1 nm respectively. The design method is based on a broadband Fabry-Perot thin-film interference filter in which the higher or lower interference band at both sides of the main transmittance peak can be used for initial design of long-wave-pass filter or short-wave-pass filter and then can be refined to reduce the transmittance ripples. The spacer 2H2L2H or 2L2H2L of the filter is usually taken. Moreover, the method for expanding the bandwidth of rejection and transmission is explained. The bandwidth of 200 nm for both rejection region and transmission band is obtained at wavelength 1550 nm. In this way, the long-wave-pass and short-wave-pass edge filters with zero separation between two polarization components can easily be fabricated.展开更多
Flexible strain sensors play an important role in electronic skins,wearable medical devices,and advanced robots.Herein,a highly sensitive and fast response optical strain sensor with two evanescently coupled optical m...Flexible strain sensors play an important role in electronic skins,wearable medical devices,and advanced robots.Herein,a highly sensitive and fast response optical strain sensor with two evanescently coupled optical micro/nanofibers(MNFs)embedded in a polydimethylsiloxane(PDMS)film is proposed.The strain sensor exhibits a gauge factor as high as 64.5 for strain≤0.5%and a strain resolution of 0.0012%which corresponds to elongation of 120 nm on a 1 cm long device.As a proof-of-concept,highly sensitive fingertip pulse measurement is realized.The properties of fast temporal frequency response up to 30 kHz and a pressure sensitivity of 102 kPa^(−1) enable the sensor for sound detection.Such versatile sensor could be of great use in physiological signal monitoring,voice recognition and micro-displacement detection.展开更多
Colorimetric characterization is to transform the device-dependent responses to device-independent colorimetric values, and is usually conducted in CIEXYZ space. However, the optimal solution in CIEXYZ space does not ...Colorimetric characterization is to transform the device-dependent responses to device-independent colorimetric values, and is usually conducted in CIEXYZ space. However, the optimal solution in CIEXYZ space does not mean the mini-mization of perceptual error. A novel method for colorimetric characterization of imaging device based on the minimization of total color difference is proposed. The method builds the transform between RGB space and CIELAB space directly using the downhill simplex algorithm. Experimental results showed that the proposed method performs better than traditional least-square (LS) and total-least-square (TLS) methods, especially for colors with low luminance values.展开更多
Polarizing beam splitter (PBS) is a critical optical component in projection display system because PBS performance greatly influences the contrast and brightness of the system. PBS performance is usually measured by ...Polarizing beam splitter (PBS) is a critical optical component in projection display system because PBS performance greatly influences the contrast and brightness of the system. PBS performance is usually measured by spectrophotometer after coating and cementing, but the measured result cannot represent the actual performance in practice because people usually change the incident angle in one plane (horizontal plane) and do not consider the other plane (vertical plane). Geometrical polarization rotation occurring at reduced F-number influences the measuring precision of s-polarization transmittance (Ts) and p-polarization reflectance (Rp). A more accurate and practical way to measure the performance of broadband, wide-angle PBS is presented in this paper.展开更多
Digital structured light （SL） profilometry is increasingly used in three-dimensional （3D） measurement technology. However, the nonlinearity of the off-the-shelf projectors and cameras seriously reduces the measure...Digital structured light （SL） profilometry is increasingly used in three-dimensional （3D） measurement technology. However, the nonlinearity of the off-the-shelf projectors and cameras seriously reduces the measurement accuracy. In this paper, first, we review the nonlinear effects of the projector-camera system in the phase-shifting structured light depth measurement method. We show that high order harmonic wave components lead to phase error in the phase-shifting method. Then a practical method based on frequency domain filtering is proposed for nonlinear error reduction. By using this method, the nonlinear calibration of the SL system is not required. Moreover, both the nonlinear effects of the projector and the camera can be effectively reduced. The simulations and experiments have verified our nonlinear correction method.展开更多
A deep understanding of the spectral gain characteristics of optical parametric oscillators (OPOs) and optical parametric amplifiers (OPAs) is important for a highly efficient optical parametric conversion. We numeric...A deep understanding of the spectral gain characteristics of optical parametric oscillators (OPOs) and optical parametric amplifiers (OPAs) is important for a highly efficient optical parametric conversion. We numerically calculated the spectral gain characteristics of a quasi-phase-matching (QPM) parametric conversion process using the periodically poled 6% (mol/mol) MgO doped LiNbO3 (PPMgLN) as the nonlinear crystal. In the simulation we utilized the approach of a transformative matrix of the periodically poled nonlinear medium, which results from the small-signal approximation of three-wave mixed nonlinear equations. Numerical simulation results show that: (1) The full width at half maximum (FWHM) of the spectral gain of the parametric process becomes wider with the increase of parametric wavelength and reaches the maximum at degeneration; (2) The gain coefficient decreases gradually with the increase of parametric wavelength; (3) The spectral gain bandwidth decreases correspondingly with the increase of the nonlinear material length; (4) There exists an optimal parametric wavelength band, which is most suitable for the high gain parametric conversion when pumped by a laser source with a wide wavelength band, such as the high power fiber laser.展开更多
The single-phase face-centered cubic(fcc)-structured Fe_(50)Mn_(27)Ni_(10)Cr_(13) high entropy alloy(HEA)exhibits good ductility but low strength,which presents a challenge.By Mo-alloying and thermomechanical treatmen...The single-phase face-centered cubic(fcc)-structured Fe_(50)Mn_(27)Ni_(10)Cr_(13) high entropy alloy(HEA)exhibits good ductility but low strength,which presents a challenge.By Mo-alloying and thermomechanical treatments,we have designed the(Fe_(50)Mn_(27)Ni_(10)Cr_(13))_(100-x)Mo_(x)(x=0-6 at.%)alloy series with a wide range of mechanical properties.The careful control of secondary phases introduced in the cold-rolled and annealed(Fe_(50)Mn_(27)Ni_(10)Cr_(13))Mo_(2) sample resulted in an enhanced tensile strength from 250 MPa to 665 MPa,still having~25%ductility.TEM investigations of this alloy revealed the presence of deformation twins,dislocation cells,and ordered bcc na no-pa rticles embedded in the ductile fcc matrix post-deformation.The observed deformation structures are an indication of succes s ful cooperation between deformation twinning and precipitation strengthening in enhancing the tensile strength at maintained ductility compared to its cast counterpart.This work provides insight into the tunability of the mechanical properties of non-equiatomic HEAs via alloying and thermomechanical processing.展开更多
A new power divider, composed of a novel composite right/left-handed (CRLH) transmission line (TL) unit, is proposed. The properties of the power divider based on four CRLH TL unit cells are investigated theoretically...A new power divider, composed of a novel composite right/left-handed (CRLH) transmission line (TL) unit, is proposed. The properties of the power divider based on four CRLH TL unit cells are investigated theoretically. By adjusting the parameters of the capacitors and the inductors, the power divider shows perfectly symmetric power division at 5.13 GHz, return loss up to ?24 dB, with the transmitted power being close to ?3.1 dB. The phenomena are demonstrated by simulation results. Being compact in size and low-cost, the proposed power divider is very suitable for microwave and millimeter wave integrated circuits.展开更多
The power conversion efficiency (PCE) of perovskite solar cells (PSCs) swiftly increased from 3.8% to more than 20% during last 10 years, thanks to the advancement of perovskite film growth, device and interface engin...The power conversion efficiency (PCE) of perovskite solar cells (PSCs) swiftly increased from 3.8% to more than 20% during last 10 years, thanks to the advancement of perovskite film growth, device and interface engineering. However, solution-processed perovskites are usually polycrystalline, that is the photoactive films contain substantial structural disorders, such as grain boundaries, interfaces and crystallographic defects. These defects have detrimental impacts on the performance and stability of PSCs.展开更多
Since the 1990s,continuous technical and scientific advances have defied the diffraction limit in microscopy and enabled three-dimensional(3D)super-resolution imaging.An important milestone in this pursuit is the cohe...Since the 1990s,continuous technical and scientific advances have defied the diffraction limit in microscopy and enabled three-dimensional(3D)super-resolution imaging.An important milestone in this pursuit is the coherent utilization of two opposing objectives(4Pi geometry)and its combination with superresolution microscopy.Herein,we review the recent progress in 4Pi nanoscopy,which provides a 3D,non-invasive,diffraction-unlimited,and isotropic resolution in transparent samples.This review includes both the targeted and stochastic switching modalities of 4Pi nanoscopy.The schematics,principles,applications,and future potential of 4Pi nanoscopy are discussed in detail.展开更多
In this Letter we outline a dielectric multilayer spectrally selective filter designed for solar energy applications.The optical performance of this 78-layer interference filter constructed by TiOx and SiO_(2) is pres...In this Letter we outline a dielectric multilayer spectrally selective filter designed for solar energy applications.The optical performance of this 78-layer interference filter constructed by TiOx and SiO_(2) is presented.A hybrid system combining photovoltaic cells with a solar-powered Stirling engine using the designed filter is analyzed.The calculated results show the advantages of this spectrally selective method for solar power generation.展开更多
Near-field scanning optical microscopy is used to investigate the waveguiding properties of optical micro/nanofibres （MNFs） by means of detecting optical power carried by evanescent waves. Taper drawn silica and tel...Near-field scanning optical microscopy is used to investigate the waveguiding properties of optical micro/nanofibres （MNFs） by means of detecting optical power carried by evanescent waves. Taper drawn silica and tellurite MNFs, supported on low-index substrates, are used to guide a 532-nm-wavelength light beam for the test. Modification of the single-mode condition of the MNF in the presence of a substrate is observed. Spatial modulation of the longitudinal field intensity （with a 195-nm period） near the output end of a 760-nm-diameter silica MNF is well resolved. Energy exchange through evanescent coupling between two parallel MNFs is also investigated.展开更多
The multimode evolution, optical losses and wavelength response of non-adiabatic micro/nano-fiber （MNF） tapers are numerically simulated using a three-dimensional finite-difference beam propagation method. For a non...The multimode evolution, optical losses and wavelength response of non-adiabatic micro/nano-fiber （MNF） tapers are numerically simulated using a three-dimensional finite-difference beam propagation method. For a non-adiabatic MNF taper, it is illustrated that optical losses vary with the transition region length and the optical wavelength. We explain how the complicated multimode evolutions result in the complicated optical loss and wavelength response properties, especially when the waist diameters are large enough to allow much higher-order modes. These results may offer valuable references for trapping and guiding cold atoms in atom optics and practical application of micro/nano-devices.展开更多
A method to tighten the cloud screening thresholds based on local conditions is used to provide more stringent schemes for Orbiting Carbon Observatory-2(OCO-2)cloud screening algorithms.Cloud screening strategies are ...A method to tighten the cloud screening thresholds based on local conditions is used to provide more stringent schemes for Orbiting Carbon Observatory-2(OCO-2)cloud screening algorithms.Cloud screening strategies are essential to remove scenes with significant cloud and/or aerosol contamination from OCO-2 observations,which helps to save on the data processing cost and ensure high quality retrievals of the column-averaged CO2 dry air mole fraction(XCO2).Based on the radiance measurements in the 0.76μm O2A band,1.61μm(weak),and 2.06μm(strong)CO2 bands,the current combination of the A-Band Preprocessor(ABP)algorithm and Iterative Maximum A Posteriori(IMAP)Differential Optical Absorption Spectroscopy(DOAS)Preprocessor(IDP)algorithm passes around 20%-25%of all soundings,which means that some contaminated scenes also pass the screening process.In this work,three independent pairs of threshold parameters used in the ABP and IDP algorithms are sufficiently tuned until the overall pass rate is close to the monthly clear-sky fraction from the MODIS cloud mask.The tightened thresholds are applied to observations over land surfaces in Europe and Japan in 2016.The results show improvement of agreement and positive predictive value compared to the collocated MODIS cloud mask,especially in summer and fall.In addition,analysis indicates that XCO2 retrievals with more stringent thresholds are in closer agreement with measurements from collocated Total Carbon Column Observing Network(TCCON)sites.展开更多
Among all the structural formations,fiber-like structure is one of the most common modalities in organisms that undertake essential functions.Alterations in spatial organization of fibrous structures can refiect infor...Among all the structural formations,fiber-like structure is one of the most common modalities in organisms that undertake essential functions.Alterations in spatial organization of fibrous structures can refiect information of physiological and pathological activities,which is of significance in both researches and clinical applications.Hence,the quantification of subtle changes in fiber-like structures is potentiallymeaningful in studying structure-function relationships,disease progression,carcinoma staging and engineered tissue remodeling.In this study,we examined a wide range of methodologies that quantify organizational and morphological features of fibrous structures,including orientation,alignment,waviness and thickness.Each method was demonstrated with specific applications.Finally,perspectives of future quantification analysis techniques were explored.展开更多
A novel asymmetric optothermal microactuator was developed. A microactuator of 750μm length was machined by an excimer laser micmmachining system using single layer material. It had an asymmetric structure consisting...A novel asymmetric optothermal microactuator was developed. A microactuator of 750μm length was machined by an excimer laser micmmachining system using single layer material. It had an asymmetric structure consisting of two thin expansion arms with different widths. A laser diode （660nm） was employed as the external power source to activate the microactuator. We introduced a charge coupled device （CCD）-combined optical microscope and a computer system to observe and capture the microactuator＇ s deflection and vibration. Experiments have been carried out to check the feasibility of deflection, and the data of deflection have been measured under different laser power as well as under different pulse frequency. The results show that the actuator can practically generate an obvious lateral deflection or vibration, the maximum could be larger than 20μm. Moreover, the deflection status of the microactuator could be controlled wirelessly or remotely by changing the laser power and its pulse frequency.展开更多
The construction of scintillating ceramics is of great technological importance for various fundamental applications, including medical diagnostic, security inspection, resource exploration and particle physics. The c...The construction of scintillating ceramics is of great technological importance for various fundamental applications, including medical diagnostic, security inspection, resource exploration and particle physics. The chief challenge is the facile and scalable synthesis of scintillating ceramics with the desirable combination of pore-free, reliable mechanical properties and excellent scintillating performance. Here we present a pressureless glass crystallization strategy for the construction of scintillating composite with high crystallinity. The fabricated scintillating composites are featured by small optical turbidity, excellent mechanical properties, and efficient scintillating luminescence with the scintillating light yield of 15,000 pH/MeV and about 2.46 times higher than that of the commercial BGO single crystal. Moreover, the scintillating composite derived radiation detector device is successfully elaborated. The practical application for monitoring gamma ray is demonstrated and the precision of the device is less than that of the tolerable deviation of 30%. Our results suggest an innovative approach for expanding the category of scintillating material candidates, pointing to practical application in the field of radiation detection.展开更多
文摘Lanthanum-bearing iron lithium borate glass is a quaternary system for oxide glasses and was prepared via the melt-quenching method.The present article correlates the structure,optical,ligand field and M?ssbauer data on iron lithium borate glass co ntaining La^(3+).The density was measured,while the molar volume was calculated.Other physical parameters are well-described.With increasing the La_(2)O_(3) content within the glass network,infrared spectra analysis reveals structural modifications such as the increase in BO_(4) units and the decline in both BO_(3) units and NBO bonds content.Furthermore,optical absorption spectra were measured.The absorption spectra disclose a plethora of electronic transitions that are related to Fe^(3+)in tetrahedral and octahedral sites,however,Fe^(2+)phase is not observed in optical spectra,but it has a clear signature in M?ssbauer spectra.Besides,the glass absorption edges undergo a clear blue shift,reflecting an increased band gap energy(1.96-2.28 eV).The decline in NBO bonds justifies this trend.Bewitchingly,the values of crystal field splitting are increased,while the values of Racah parameters are decreased.This trend is justified by the decline in NBO bonds and increases electron localization around Fe cations.M?ssbauer spectra confirm the existence of Fe^(3+)in tetrahedral and octahedral sites,while Fe^(2+)exists in only a tetrahedral state.With increasing La_(2)O_(3) content,the isomer shift of Fe^(3+)in tetrahedral sites changes to be 0.312-0.329 mm/s,while the isomer shift of octahedral Fe^(3+)is 0.424-0.456 mm/s.These findings coincide with optical data.While the isomer shift of tetrahedral Fe^(2+)is 0.902-0.911 mm/s.Our results of structural,optical and ligand field associated with M?ssbauer spectra open more vistas toward the utility of these samples in the optics realm.
基金Education Department of Zhejiang Province(Project No.:201942041)the Health Commission of Zhejiang Province(Project No.:W20008)the Science and Technology program of Jinhua Science and Technology Bureau(Project No.:2020-4-106).
文摘Purpose:To examine the changes in choroidal thickness(ChT)after 6-month topical treatment of 0.01%atropine eye drops in myopic children.Methods:A total of 46 low to moderate myopic children aged 8 to 12 years were recruited and received topical 0.01%atropine once a day for 6 months.Spherical equivalent(SE),axial length(AL),and ChT were measured at baseline,3 months,and 6 months.Results:During the first and second 3-month treatment,there is no significant decrease in progression of SE and AL.Within the range of 3 mm from the temporal side of the fovea to the nasal side,no significant changes in ChT have been observed at any measuring points in low and moderate myopic participants.Changes in ChT were not significantly associated with gender or AL progression.Conclusion:A 6-month topical treatment of 0.01%atropine could not cause significant changes in ChT in myopic children.
基金financially supported by the National Natural Science Foundation of China (Nos. 21835001, 51773080, 21674041, 51573068, and 21221063)Program for Changbaishan Scholars of Jilin Province, Jilin Province (No. 20160101305JC)the "Talents Cultivation Program" of Jilin University
文摘Near-infrared(NIR) nanoparticles(NPs) based on fluorescence resonance energy transfer(FRET) were prepared by coencapsulation of a red aggregation-induced emission(AIE) molecule, 2-(4-bromophenyl)-3-(4-(4-(diphenylamino)styryl)phenyl)fumaronitrile(TB), and a commercial NIR fluorescence dye, silicon 2,3-naphthalocyanine bis(trihexylsilyloxide)(NIR775) with an amphiphilic polymer poly(styrene-co-maleic anhydride)(PSMA). The surface of the NPs, PSMA@TB/NIR775, was modified with poly(ethylene glycol)(PEG) to increase the in vivo biocompatibility of the NPs. The PSMA@TB/NIR775 NPs showed a strong NIR(780 nm) narrow emission and excellent two-photon absorption property. Moreover, the NPs exhibited good monodispersity, stability, and low cytotoxicity.Under the excitation of a 1040 nm femtosecond(fs) laser, the emission peaks at 680 nm of TB and 780 nm of NIR775 excited by FRET were obtained. We utilized PSMA@TB/NIR775 NPs as fluorescent contrast agents for two-photon excited NIR microscopic imaging, and good NIR imaging effect of mouse brain vasculature was obtained with the imaging depth of about 150 μm. The FRET strategy by coencapsulating AIE molecule and NIR dye will be helpful in preparing more narrow emission NIR probes for deep-tissue biological imaging.
基金Project (No. 60078001) supported by the National Natural ScienceFoundation of China
文摘The separation between s- and p-polarization components invariably affects thin film edge filters used for tilted incidence and is a difficult problem for many applications, especially for optical communication. This paper presents a novel design method to obtain edge filters with non-polarization at incidence angle of 45°. The polarization separation at 50% trans-mittance for a long-wave-pass filter and a short-wave-pass filter is 0.3 nm and 0.1 nm respectively. The design method is based on a broadband Fabry-Perot thin-film interference filter in which the higher or lower interference band at both sides of the main transmittance peak can be used for initial design of long-wave-pass filter or short-wave-pass filter and then can be refined to reduce the transmittance ripples. The spacer 2H2L2H or 2L2H2L of the filter is usually taken. Moreover, the method for expanding the bandwidth of rejection and transmission is explained. The bandwidth of 200 nm for both rejection region and transmission band is obtained at wavelength 1550 nm. In this way, the long-wave-pass and short-wave-pass edge filters with zero separation between two polarization components can easily be fabricated.
基金We are grateful for financial supports from the National Natural Science Foundation of China(No.61975173)the National Key Research and Development Program of China(No.SQ2019YFC170311)+3 种基金the Major Scientific Research Project of Zhejiang Lab(No.2019MC0AD01)the Key Research and Development Project of Zhejiang Province(No.2021C05003)the Quantum Joint Funds of the Natural Foundation of Shandong Province(No.ZR2020LLZ007)the CIE-Tencent Robotics X Rhino-Bird Focused Research Program(No.2020-01-006).
文摘Flexible strain sensors play an important role in electronic skins,wearable medical devices,and advanced robots.Herein,a highly sensitive and fast response optical strain sensor with two evanescently coupled optical micro/nanofibers(MNFs)embedded in a polydimethylsiloxane(PDMS)film is proposed.The strain sensor exhibits a gauge factor as high as 64.5 for strain≤0.5%and a strain resolution of 0.0012%which corresponds to elongation of 120 nm on a 1 cm long device.As a proof-of-concept,highly sensitive fingertip pulse measurement is realized.The properties of fast temporal frequency response up to 30 kHz and a pressure sensitivity of 102 kPa^(−1) enable the sensor for sound detection.Such versatile sensor could be of great use in physiological signal monitoring,voice recognition and micro-displacement detection.
文摘Colorimetric characterization is to transform the device-dependent responses to device-independent colorimetric values, and is usually conducted in CIEXYZ space. However, the optimal solution in CIEXYZ space does not mean the mini-mization of perceptual error. A novel method for colorimetric characterization of imaging device based on the minimization of total color difference is proposed. The method builds the transform between RGB space and CIELAB space directly using the downhill simplex algorithm. Experimental results showed that the proposed method performs better than traditional least-square (LS) and total-least-square (TLS) methods, especially for colors with low luminance values.
基金(No. 2004C31107) supported by the Science and Technology Program of Zhejiang Province, China
文摘Polarizing beam splitter (PBS) is a critical optical component in projection display system because PBS performance greatly influences the contrast and brightness of the system. PBS performance is usually measured by spectrophotometer after coating and cementing, but the measured result cannot represent the actual performance in practice because people usually change the incident angle in one plane (horizontal plane) and do not consider the other plane (vertical plane). Geometrical polarization rotation occurring at reduced F-number influences the measuring precision of s-polarization transmittance (Ts) and p-polarization reflectance (Rp). A more accurate and practical way to measure the performance of broadband, wide-angle PBS is presented in this paper.
基金Project supported by the Science and Technology Major Projects of Zhejiang Province,China(Grant No.2013C03043-5)
文摘Digital structured light （SL） profilometry is increasingly used in three-dimensional （3D） measurement technology. However, the nonlinearity of the off-the-shelf projectors and cameras seriously reduces the measurement accuracy. In this paper, first, we review the nonlinear effects of the projector-camera system in the phase-shifting structured light depth measurement method. We show that high order harmonic wave components lead to phase error in the phase-shifting method. Then a practical method based on frequency domain filtering is proposed for nonlinear error reduction. By using this method, the nonlinear calibration of the SL system is not required. Moreover, both the nonlinear effects of the projector and the camera can be effectively reduced. The simulations and experiments have verified our nonlinear correction method.
基金supported by the National Natural Science Foundation of China (No. 60778001)the National Basic Research Program (973) of China (No. 2007CB307003)
文摘A deep understanding of the spectral gain characteristics of optical parametric oscillators (OPOs) and optical parametric amplifiers (OPAs) is important for a highly efficient optical parametric conversion. We numerically calculated the spectral gain characteristics of a quasi-phase-matching (QPM) parametric conversion process using the periodically poled 6% (mol/mol) MgO doped LiNbO3 (PPMgLN) as the nonlinear crystal. In the simulation we utilized the approach of a transformative matrix of the periodically poled nonlinear medium, which results from the small-signal approximation of three-wave mixed nonlinear equations. Numerical simulation results show that: (1) The full width at half maximum (FWHM) of the spectral gain of the parametric process becomes wider with the increase of parametric wavelength and reaches the maximum at degeneration; (2) The gain coefficient decreases gradually with the increase of parametric wavelength; (3) The spectral gain bandwidth decreases correspondingly with the increase of the nonlinear material length; (4) There exists an optimal parametric wavelength band, which is most suitable for the high gain parametric conversion when pumped by a laser source with a wide wavelength band, such as the high power fiber laser.
基金financially supported by the National Natural Science Foundation of China(Nos.U1832203,11975202and 51871198)the National Key Research and Development Program of China(Nos.2016YFB0701203,2016YFB0700201,and 2017YFA0403400)+1 种基金the Natural Science Foundation of Zhejiang Province(Nos.Z1110196,Y4110192,and LY15E010003)the Fundamental Research Funds for the Central Universities。
文摘The single-phase face-centered cubic(fcc)-structured Fe_(50)Mn_(27)Ni_(10)Cr_(13) high entropy alloy(HEA)exhibits good ductility but low strength,which presents a challenge.By Mo-alloying and thermomechanical treatments,we have designed the(Fe_(50)Mn_(27)Ni_(10)Cr_(13))_(100-x)Mo_(x)(x=0-6 at.%)alloy series with a wide range of mechanical properties.The careful control of secondary phases introduced in the cold-rolled and annealed(Fe_(50)Mn_(27)Ni_(10)Cr_(13))Mo_(2) sample resulted in an enhanced tensile strength from 250 MPa to 665 MPa,still having~25%ductility.TEM investigations of this alloy revealed the presence of deformation twins,dislocation cells,and ordered bcc na no-pa rticles embedded in the ductile fcc matrix post-deformation.The observed deformation structures are an indication of succes s ful cooperation between deformation twinning and precipitation strengthening in enhancing the tensile strength at maintained ductility compared to its cast counterpart.This work provides insight into the tunability of the mechanical properties of non-equiatomic HEAs via alloying and thermomechanical processing.
基金Project supported by the National Natural Science Foundation of China (Nos. 60577023 and 60378037), the National Basic Research Program (973) of China (No. 2004CB719802), China Postdoctoral Science Foundation, and Education Ministry Key Laboratory of Photoelectric Information Technology Science Foundation (No. 2005-20), China
文摘A new power divider, composed of a novel composite right/left-handed (CRLH) transmission line (TL) unit, is proposed. The properties of the power divider based on four CRLH TL unit cells are investigated theoretically. By adjusting the parameters of the capacitors and the inductors, the power divider shows perfectly symmetric power division at 5.13 GHz, return loss up to ?24 dB, with the transmitted power being close to ?3.1 dB. The phenomena are demonstrated by simulation results. Being compact in size and low-cost, the proposed power divider is very suitable for microwave and millimeter wave integrated circuits.
文摘The power conversion efficiency (PCE) of perovskite solar cells (PSCs) swiftly increased from 3.8% to more than 20% during last 10 years, thanks to the advancement of perovskite film growth, device and interface engineering. However, solution-processed perovskites are usually polycrystalline, that is the photoactive films contain substantial structural disorders, such as grain boundaries, interfaces and crystallographic defects. These defects have detrimental impacts on the performance and stability of PSCs.
基金financially supported by the grants from National Key Research and Development Program of China (2018YFA0701400 and 2018YFE0119000)the Fundamental Research Funds for the Central Universities (2019QNA5006)+2 种基金ZJU-Sunny Photonics Innovation Center (2019-01)Zhejiang Provincial Natural Science Foundation of China (LR18H180001)startup grant from Southern University of Science and Technology
文摘Since the 1990s,continuous technical and scientific advances have defied the diffraction limit in microscopy and enabled three-dimensional(3D)super-resolution imaging.An important milestone in this pursuit is the coherent utilization of two opposing objectives(4Pi geometry)and its combination with superresolution microscopy.Herein,we review the recent progress in 4Pi nanoscopy,which provides a 3D,non-invasive,diffraction-unlimited,and isotropic resolution in transparent samples.This review includes both the targeted and stochastic switching modalities of 4Pi nanoscopy.The schematics,principles,applications,and future potential of 4Pi nanoscopy are discussed in detail.
基金Supported by the Research Foundation of Science and Technology Department of Zhejiang Province(2009C21023).
文摘In this Letter we outline a dielectric multilayer spectrally selective filter designed for solar energy applications.The optical performance of this 78-layer interference filter constructed by TiOx and SiO_(2) is presented.A hybrid system combining photovoltaic cells with a solar-powered Stirling engine using the designed filter is analyzed.The calculated results show the advantages of this spectrally selective method for solar power generation.
基金Supported by the National Natural Science Foundation of China under Grant Nos 60425517 and 60378036.
文摘Near-field scanning optical microscopy is used to investigate the waveguiding properties of optical micro/nanofibres （MNFs） by means of detecting optical power carried by evanescent waves. Taper drawn silica and tellurite MNFs, supported on low-index substrates, are used to guide a 532-nm-wavelength light beam for the test. Modification of the single-mode condition of the MNF in the presence of a substrate is observed. Spatial modulation of the longitudinal field intensity （with a 195-nm period） near the output end of a 760-nm-diameter silica MNF is well resolved. Energy exchange through evanescent coupling between two parallel MNFs is also investigated.
基金Supported by the National Natural Science Foundation of China under Crant No 60407003, and the National Basic Research Program of China under Grant No 2007CB307003.
文摘The multimode evolution, optical losses and wavelength response of non-adiabatic micro/nano-fiber （MNF） tapers are numerically simulated using a three-dimensional finite-difference beam propagation method. For a non-adiabatic MNF taper, it is illustrated that optical losses vary with the transition region length and the optical wavelength. We explain how the complicated multimode evolutions result in the complicated optical loss and wavelength response properties, especially when the waist diameters are large enough to allow much higher-order modes. These results may offer valuable references for trapping and guiding cold atoms in atom optics and practical application of micro/nano-devices.
基金the National Key Research Program of China(Grant No.2016YFC0200900)the National Natural Science Foundation of China(NSFC)(Grant No.41775023)+1 种基金the Excellent Young Scientists Program of the Zhejiang Provincial Natural Science Foundation of China(Grant No.LR19D050001)the Fundamental Research Funds for the Central Universities,and the State Key Laboratory of Modern Optical Instrumentation Innovation Program.
文摘A method to tighten the cloud screening thresholds based on local conditions is used to provide more stringent schemes for Orbiting Carbon Observatory-2(OCO-2)cloud screening algorithms.Cloud screening strategies are essential to remove scenes with significant cloud and/or aerosol contamination from OCO-2 observations,which helps to save on the data processing cost and ensure high quality retrievals of the column-averaged CO2 dry air mole fraction(XCO2).Based on the radiance measurements in the 0.76μm O2A band,1.61μm(weak),and 2.06μm(strong)CO2 bands,the current combination of the A-Band Preprocessor(ABP)algorithm and Iterative Maximum A Posteriori(IMAP)Differential Optical Absorption Spectroscopy(DOAS)Preprocessor(IDP)algorithm passes around 20%-25%of all soundings,which means that some contaminated scenes also pass the screening process.In this work,three independent pairs of threshold parameters used in the ABP and IDP algorithms are sufficiently tuned until the overall pass rate is close to the monthly clear-sky fraction from the MODIS cloud mask.The tightened thresholds are applied to observations over land surfaces in Europe and Japan in 2016.The results show improvement of agreement and positive predictive value compared to the collocated MODIS cloud mask,especially in summer and fall.In addition,analysis indicates that XCO2 retrievals with more stringent thresholds are in closer agreement with measurements from collocated Total Carbon Column Observing Network(TCCON)sites.
基金supported by National Key Research and Development Program of China (2019YFE0113700 and 2017YFA0700501)National Natural Science Foundation of China (61905214,62035011,11974310 and 31927801)Natural Science Foundation of Zhejiang Province (LR20F050001).
文摘Among all the structural formations,fiber-like structure is one of the most common modalities in organisms that undertake essential functions.Alterations in spatial organization of fibrous structures can refiect information of physiological and pathological activities,which is of significance in both researches and clinical applications.Hence,the quantification of subtle changes in fiber-like structures is potentiallymeaningful in studying structure-function relationships,disease progression,carcinoma staging and engineered tissue remodeling.In this study,we examined a wide range of methodologies that quantify organizational and morphological features of fibrous structures,including orientation,alignment,waviness and thickness.Each method was demonstrated with specific applications.Finally,perspectives of future quantification analysis techniques were explored.
基金Supported by the National High Technology Research and Development Program of China (No. 2006AA04Z237)the National Natural Science Foundation of China (No. 50775205)
文摘A novel asymmetric optothermal microactuator was developed. A microactuator of 750μm length was machined by an excimer laser micmmachining system using single layer material. It had an asymmetric structure consisting of two thin expansion arms with different widths. A laser diode （660nm） was employed as the external power source to activate the microactuator. We introduced a charge coupled device （CCD）-combined optical microscope and a computer system to observe and capture the microactuator＇ s deflection and vibration. Experiments have been carried out to check the feasibility of deflection, and the data of deflection have been measured under different laser power as well as under different pulse frequency. The results show that the actuator can practically generate an obvious lateral deflection or vibration, the maximum could be larger than 20μm. Moreover, the deflection status of the microactuator could be controlled wirelessly or remotely by changing the laser power and its pulse frequency.
基金financially supported by the National Science Fund for Distinguished Young Scholars(No.62125502)the National Natural Science Foundation of China(No.51972113)+4 种基金the Key Program of Guangzhou Scientific Research Special Project(No.201904020013)the Key R&D Program of Guangzhou(No.202007020003)the Science and Technology Project of Guangdong Province(No.2021A0505030004)the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(No.2017BT01×137)the Fundamental Research Funds for the Central University。
文摘The construction of scintillating ceramics is of great technological importance for various fundamental applications, including medical diagnostic, security inspection, resource exploration and particle physics. The chief challenge is the facile and scalable synthesis of scintillating ceramics with the desirable combination of pore-free, reliable mechanical properties and excellent scintillating performance. Here we present a pressureless glass crystallization strategy for the construction of scintillating composite with high crystallinity. The fabricated scintillating composites are featured by small optical turbidity, excellent mechanical properties, and efficient scintillating luminescence with the scintillating light yield of 15,000 pH/MeV and about 2.46 times higher than that of the commercial BGO single crystal. Moreover, the scintillating composite derived radiation detector device is successfully elaborated. The practical application for monitoring gamma ray is demonstrated and the precision of the device is less than that of the tolerable deviation of 30%. Our results suggest an innovative approach for expanding the category of scintillating material candidates, pointing to practical application in the field of radiation detection.
