Transparent microwave absorbers that exhibit high optical transmittance and microwave absorption capability are ideal,although having a fixed absorption performance limits their applicability.Here,a simple,transparent...Transparent microwave absorbers that exhibit high optical transmittance and microwave absorption capability are ideal,although having a fixed absorption performance limits their applicability.Here,a simple,transparent,and thermally tunable microwave absorber is proposed,based on a patterned vanadium dioxide(VO_(2))film.Numerical calculations and experiments demonstrate that the proposed VO_(2)absorber has a high optical transmittance of 84.9%at 620 nm;its reflection loss at 15.06 GHz can be thermally tuned from–4.257 to–60.179 dB,and near-unity absorption is achieved at 523.750 K.Adjusting only the patterned VO_(2)film duty cycle can change the temperature of near-unity absorption.Our VO_(2)absorber has a simple composition,a high optical transmittance,a thermally tunable microwave absorption performance,a large modulation depth,and an adjustable temperature tuning range,making it promising for application in tunable sensors,thermal emitters,modulators,thermal imaging,bolometers,and photovoltaic devices.展开更多
A compact multi-throttle aerostatic guideway is the preferred structure for high precision and acceleration motion in the variable-slit system(VS)of photolithography.The presence of microstructure,such as recesses and...A compact multi-throttle aerostatic guideway is the preferred structure for high precision and acceleration motion in the variable-slit system(VS)of photolithography.The presence of microstructure,such as recesses and grooves,on the guideway working surface has been found to improve the loading performance.Nevertheless,the effects on the guideway performance of changing the microstructure on the micron level are not yet clear.The mesh adaptation method,which was proposed by the authors,is employed in this paper to quantitatively study the influences of four microstructure parameters.The effect of tuning these parameters on the loading performance is revealed.The level of impact determines the proposed design process of the parameters.The characteristic feature of the proposed design process is that the working points of carrying capacity,stiffness,and rotational stiffness are unified under twoway adjusting by means of recess parameters.According to the proposed design process and tuning method,the restriction of supply pressure is lifted to a certain extent and the mutual tradeoff among the loading performances is relieved.The experimental results show that the rotational stiffness of the designed guideway,based on the tuned parameters,reached 2.14×10^(4) Nmrad1 and increased by 69.8%.In a scanning test of the applied VS on argon fluoride laser(ArF)photolithography,the average scanning acceleration reached 67.5 m·s^(-2),meeting the design specification.展开更多
Optical deep learning based on diffractive optical elements offers unique advantages for parallel processing,computational speed,and power efficiency.One landmark method is the diffractive deep neural network(D^(2) NN...Optical deep learning based on diffractive optical elements offers unique advantages for parallel processing,computational speed,and power efficiency.One landmark method is the diffractive deep neural network(D^(2) NN)based on three-dimensional printing technology operated in the terahertz spectral range.Since the terahertz bandwidth involves limited interparticle coupling and material losses,this paper extends D^(2) NN to visible wavelengths.A general theory including a revised formula is proposed to solve any contradictions between wavelength,neuron size,and fabrication limitations.A novel visible light D^(2) NN classifier is used to recognize unchanged targets(handwritten digits ranging from 0 to 9)and targets that have been changed(i.e.,targets that have been covered or altered)at a visible wavelength of 632.8 nm.The obtained experimental classification accuracy(84%)and numerical classification accuracy(91.57%)quantify the match between the theoretical design and fabricated system performance.The presented framework can be used to apply a D^(2) NN to various practical applications and design other new applications.展开更多
Dear editor,This letter designs the event-triggered control(ETC)to achieve finite-time stabilization(FTS)of linear systems with input constraints.The key idea of the established algorithm is that the designed time-var...Dear editor,This letter designs the event-triggered control(ETC)to achieve finite-time stabilization(FTS)of linear systems with input constraints.The key idea of the established algorithm is that the designed time-varying high-gain is only scheduled on a specified time determined by an event-triggered mechanism.展开更多
In recent years, two major challenges have arisen in the field of measurement and instrument technology. One is the redefinition of the seven basic units in the international system of units(Système Internationa...In recent years, two major challenges have arisen in the field of measurement and instrument technology. One is the redefinition of the seven basic units in the international system of units(Système International d’Unités or SI). The SI is now based on fundamental physical constants, with full implementation having occurred in 2019.展开更多
In fluorescence microscopy,computational algorithms have been developed to suppress noise,enhance contrast,and even enable super-resolution(SR).However,the local quality of the images may vary on multiple scales,and t...In fluorescence microscopy,computational algorithms have been developed to suppress noise,enhance contrast,and even enable super-resolution(SR).However,the local quality of the images may vary on multiple scales,and these differences can lead to misconceptions.Current mapping methods fail to finely estimate the local quality,challenging to associate the SR scale content.Here,we develop a rolling Fourier ring correlation(rFRC)method to evaluate the reconstruction uncertainties down to SR scale.To visually pinpoint regions with low reliability,a filtered rFRC is combined with a modified resolution-scaled error map(RSM),offering a comprehensive and concise map for further examination.We demonstrate their performances on various SR imaging modalities,and the resulting quantitative maps enable better SR images integrated from different reconstructions.Overall,we expect that our framework can become a routinely used tool for biologists in assessing their image datasets in general and inspire further advances in the rapidly developing field of computational imaging.展开更多
The spectral purity of fiber lasers has become a critical issue in both optical sensing and communication fields.As a result of ultra-narrow intrinsic linewidth, stimulated thermal Rayleigh scattering(STRS) has presen...The spectral purity of fiber lasers has become a critical issue in both optical sensing and communication fields.As a result of ultra-narrow intrinsic linewidth, stimulated thermal Rayleigh scattering(STRS) has presented special potential to compress the linewidth of fiber lasers. To suppress stimulated Brillouin scattering(SBS), the most dominant disturbance for STRS in optical fibers, a semi-quantitative estimation has been established to illuminate the mechanism of suppressing SBS in a periodic tapered fiber, and it agrees with experimental results. Finally, a linewidth compression device based on STRS is integrated into a single-longitudinal-mode ring-cavity fiber laser with secondary cavities, and its linewidth is verified to be 200 Hz through a self-heterodyne detecting and Voigt fitting method.展开更多
Finding the optimal optoelectronic properties(zero-order optical transmittance,shielding effectiveness,and stray light uniformity)of metallic mesh is significant for its application in electromagnetic interference shi...Finding the optimal optoelectronic properties(zero-order optical transmittance,shielding effectiveness,and stray light uniformity)of metallic mesh is significant for its application in electromagnetic interference shielding areas.However,there are few relevant studies at present.Based on optoelectronic properties,we propose a comprehensive evaluation factor Q,which is simple in form and can be used to evaluate the mesh with different parameters in a simple and efficient way.The effectivity of Q is verified by comparing the trend of Q values with the evaluation results of the technique for order preference by similarity to ideal solution(TOPSIS).The evaluation factor Q can also be extended to evaluate the optoelectronic properties of different kinds of metallic meshes,which makes it extremely favorable for metallic mesh design and application.展开更多
Textured BaTiO_(3)(BT)-based lead-free ceramics have gained significant attention due to their high piezoelectric coefficient(d)and very large field induced strain(S).However,costly nano-size raw materials,excessively...Textured BaTiO_(3)(BT)-based lead-free ceramics have gained significant attention due to their high piezoelectric coefficient(d)and very large field induced strain(S).However,costly nano-size raw materials,excessively high sintering temperature and low Curie temperature(T_(c))hinder their device applications.In this work,highly[001]_(c)-oriented(Ba_(0.95)Ca_(0.05))(Zr_(0.04)Ti_(0.96))O_(3) ceramics with x mol%CuO(x=0.25,0.5,1.0,2.5)denoted as BCZT-x were synthesized by templated grain growth using micro-sized raw powders.The introduction of CuO sintering agent lowered the sintering temperature by 125℃ to 1450℃,and the BCZT-1.0 achieved a high texture degree of∼99%.In addition,the CuO-based liquid phases eliminated boundaries between BT templates and BCZT matrix powders.Such liquid-phase sintering reduced sintering stresses,decreased the average grain size of BCZT-1.0 from 16μm down to 13μm,and increased the dielectric dispersion coefficientγto 1.63.The almost smoothed out T_(O-T) anomaly in the temperature dependence of dielectric permittivity and comparably high T_(c)(>102℃)lead to better temperature stability.The narrower grain orientation distribution with full width at half maximum(FWHM)of∼5.9°and smaller domains with the size of 0.1–0.5μm in width and 3–8μm in length were obtained,a high field induced maximum strain S_(max) of 0.38%and low H_(s) of 5.2%have been achieved in BCZT-1.0 textured ceramics together with a high and homogeneous piezoelectric stress coefficient d_(33)∼780 pC/N and very large d_(33)∗∼2950 pm/V.展开更多
This paper presents a dynamic and static error transfer model and uncertainty evaluation method for a high-speed variable-slit system based on a two- dimensional orthogonal double-layer air-floating guide rail structu...This paper presents a dynamic and static error transfer model and uncertainty evaluation method for a high-speed variable-slit system based on a two- dimensional orthogonal double-layer air-floating guide rail structure. The motion accuracy of the scanning blade is affected by both the moving component it is attached to and the moving component of the following blade during high-speed motion. First, an error transfer model of the high-speed variable-slit system is established, and the influence coefficients are calculated for each source of error associated with the accuracy of the blade motion. Then, the maximum range of each error source is determined by simulation and experiment. Finally, the uncertainty of the blade displacement measurement is evaluated using the Monte Carlo method. The proposed model can evaluate the performance of the complex mechanical system and be used to guide the design.展开更多
In the semiconductor manufacturing industry,the dynamic model of a controlled object is usually obtained from a frequency sweeping method before motion control.However,the existing isolators cannot properly isolate th...In the semiconductor manufacturing industry,the dynamic model of a controlled object is usually obtained from a frequency sweeping method before motion control.However,the existing isolators cannot properly isolate the disturbance of the inertial force on the platform base during frequency sweeping(the frequency is between 0 Hz and the natural frequency).In this paper,an adjustable anti-resonance frequency controller for a dual-stage actuation semi-active vibration isolation system(DSASAVIS)is proposed.This system has a significant anti-resonance characteristic;that is,the vibration amplitude can drop to nearly zero at a particular frequency,which is called the anti-resonance frequency.The proposed controller is designed to add an adjustable anti-resonance frequency to fully use this unique anti-resonance characteristic.Experimental results show that the closed-loop transmissibility is less than−15 dB from 0 Hz to the initial anti-resonance frequency.Furthermore,it is less than−30 dB around an added anti-resonance frequency which can be adjusted from 0 Hz to the initial anti-resonance frequency by changing the parameters of the proposed controller.With the proposed controller,the disturbance amplitude of the payload decays from 4 to 0.5 mm/s with a reduction of 87.5%for the impulse disturbance applied to the platform base.Simultaneously,the system can adjust the anti-resonance frequency point in real time by tracking the frequency sweeping disturbances,and a good vibration isolation performance is achieved.This indicates that the DSA-SAVIS and the proposed controller can be applied in the guarantee of an ultra-low vibration environment,especially at frequency sweeping in the semiconductor manufacturing industry.展开更多
Representation of orientation is important in a six-degree-of-freedom grating interferometer but only a few studies have focused on this topic.Roll-pitch-yaw angles,widely used in aviation,navigation,and robotics,are ...Representation of orientation is important in a six-degree-of-freedom grating interferometer but only a few studies have focused on this topic.Roll-pitch-yaw angles,widely used in aviation,navigation,and robotics,are now being brought to the field of multi-degree-of-freedom interferometric measurement.However,the roll-pitch-yaw angles are not the exact definitions the metrologists expected in interferometry,because they require a certain sequential order of rotations and may cause errors in describing complicated rotations.The errors increase as the tip and tilt angles of the grating increase.Therefore,a replacement based on fused angles in robotics is proposed and named“fused-like angles.”The fused-like angles are error-free,so they are more in line with the definitions in grating interferometry and more suitable for six-degree-of-freedom measurements.Fused-like angles have already been used in research on the kinematic model and decoupling algorithm of the six-degree-of-freedom grating interferometer.展开更多
We propose a precision phase-generated-carrier(PGC) demodulation method with sub-nanometer resolution that avoids nonlinear errors in a laser wavelength sinusoidal modulation fiber-optic interferometer for long range ...We propose a precision phase-generated-carrier(PGC) demodulation method with sub-nanometer resolution that avoids nonlinear errors in a laser wavelength sinusoidal modulation fiber-optic interferometer for long range dynamic displacement sensing.Using orthogonal detection and an AC-DC component extraction scheme,the PGC carrier phase delay(CPD) and laser intensity modulation phase delay can be obtained simultaneously to eliminate the nonlinear error from accompanied optical intensity modulation and CPD.Further,to realize long range displacement sensing,PGC phase modulation depth(PMD),determined by the laser wavelength modulation amplitude and the working distance of the interferometer,is required to maintain an optimal value during measurement,including initial position and dynamic movement.By combining frequency sweeping interference and modified PGC-arctan demodulation to measure real-time working distance,adaptive PMD technology is realized based on proportion control.We construct a fiber-optic Michelson and SIOS commercial interferometer for comparison and perform experiments to verify the feasibility of the proposed method.Experimental results demonstrate that an interferometer with sub-nanometer resolution and nanometer precision over a large range of 400 mm can be realized.展开更多
基金support from the National Natural Science Foundation of China(61975046)。
文摘Transparent microwave absorbers that exhibit high optical transmittance and microwave absorption capability are ideal,although having a fixed absorption performance limits their applicability.Here,a simple,transparent,and thermally tunable microwave absorber is proposed,based on a patterned vanadium dioxide(VO_(2))film.Numerical calculations and experiments demonstrate that the proposed VO_(2)absorber has a high optical transmittance of 84.9%at 620 nm;its reflection loss at 15.06 GHz can be thermally tuned from–4.257 to–60.179 dB,and near-unity absorption is achieved at 523.750 K.Adjusting only the patterned VO_(2)film duty cycle can change the temperature of near-unity absorption.Our VO_(2)absorber has a simple composition,a high optical transmittance,a thermally tunable microwave absorption performance,a large modulation depth,and an adjustable temperature tuning range,making it promising for application in tunable sensors,thermal emitters,modulators,thermal imaging,bolometers,and photovoltaic devices.
基金This work was funded by the National Natural Science Foundation of China(51675136)the National Science and Technology Major Project(2017ZX02101006-005)the Heilongjiang Natural Science Foundation(E2017032).
文摘A compact multi-throttle aerostatic guideway is the preferred structure for high precision and acceleration motion in the variable-slit system(VS)of photolithography.The presence of microstructure,such as recesses and grooves,on the guideway working surface has been found to improve the loading performance.Nevertheless,the effects on the guideway performance of changing the microstructure on the micron level are not yet clear.The mesh adaptation method,which was proposed by the authors,is employed in this paper to quantitatively study the influences of four microstructure parameters.The effect of tuning these parameters on the loading performance is revealed.The level of impact determines the proposed design process of the parameters.The characteristic feature of the proposed design process is that the working points of carrying capacity,stiffness,and rotational stiffness are unified under twoway adjusting by means of recess parameters.According to the proposed design process and tuning method,the restriction of supply pressure is lifted to a certain extent and the mutual tradeoff among the loading performances is relieved.The experimental results show that the rotational stiffness of the designed guideway,based on the tuned parameters,reached 2.14×10^(4) Nmrad1 and increased by 69.8%.In a scanning test of the applied VS on argon fluoride laser(ArF)photolithography,the average scanning acceleration reached 67.5 m·s^(-2),meeting the design specification.
基金This research was supported in part by National Natural Science Foundation of China(61675056 and 61875048).
文摘Optical deep learning based on diffractive optical elements offers unique advantages for parallel processing,computational speed,and power efficiency.One landmark method is the diffractive deep neural network(D^(2) NN)based on three-dimensional printing technology operated in the terahertz spectral range.Since the terahertz bandwidth involves limited interparticle coupling and material losses,this paper extends D^(2) NN to visible wavelengths.A general theory including a revised formula is proposed to solve any contradictions between wavelength,neuron size,and fabrication limitations.A novel visible light D^(2) NN classifier is used to recognize unchanged targets(handwritten digits ranging from 0 to 9)and targets that have been changed(i.e.,targets that have been covered or altered)at a visible wavelength of 632.8 nm.The obtained experimental classification accuracy(84%)and numerical classification accuracy(91.57%)quantify the match between the theoretical design and fabricated system performance.The presented framework can be used to apply a D^(2) NN to various practical applications and design other new applications.
基金supported in part by the National Natural Science Foundation of China(52075132,51907038)the State Key Laboratory of Digital Manufacturing Equipment&Technology(Huazhong University of Science and Technology)(DMETKF2020024)。
文摘Dear editor,This letter designs the event-triggered control(ETC)to achieve finite-time stabilization(FTS)of linear systems with input constraints.The key idea of the established algorithm is that the designed time-varying high-gain is only scheduled on a specified time determined by an event-triggered mechanism.
文摘In recent years, two major challenges have arisen in the field of measurement and instrument technology. One is the redefinition of the seven basic units in the international system of units(Système International d’Unités or SI). The SI is now based on fundamental physical constants, with full implementation having occurred in 2019.
基金supported by the National Natural Science Foundation of China(grant no.T2222009 to H.L.,grant no.32227802 to L.C.,grant no.81925022 to L.C.,grant no.92054301 to L.C.,grant no.62305083 to W.Z.,grant no.12174208 to P.L.,grant no.32301257 to S.Z.,grant no.32222022 to Y.J.,grant no.32071458 to H.M.)the National Key Research and Development Program of China(grant no.2022YFC3400600 to L.C.)+4 种基金the Natural Science Foundation of Heilongjiang Province(grant no.YQ2021F013 to H.L.)the Beijing Natural Science Foundation(grant no.Z20J00059 to L.C.)the Guangdong Major Project of Basic and Applied Basic Research(grant no.2020B0301030009 to P.L.)the China Postdoctoral Science Foundation(grant no.2023T160163 to W.Z.,grant no.2022M720971 to W.Z.)the Heilongjiang Provincial Postdoctoral Science Foundation(grant no.LBH-Z22027 to W.Z.).L.C.acknowledges support from the High-performance Computing Platform of Peking University。
文摘In fluorescence microscopy,computational algorithms have been developed to suppress noise,enhance contrast,and even enable super-resolution(SR).However,the local quality of the images may vary on multiple scales,and these differences can lead to misconceptions.Current mapping methods fail to finely estimate the local quality,challenging to associate the SR scale content.Here,we develop a rolling Fourier ring correlation(rFRC)method to evaluate the reconstruction uncertainties down to SR scale.To visually pinpoint regions with low reliability,a filtered rFRC is combined with a modified resolution-scaled error map(RSM),offering a comprehensive and concise map for further examination.We demonstrate their performances on various SR imaging modalities,and the resulting quantitative maps enable better SR images integrated from different reconstructions.Overall,we expect that our framework can become a routinely used tool for biologists in assessing their image datasets in general and inspire further advances in the rapidly developing field of computational imaging.
基金National Natural Science Foundation of China(NSFC)(51575140,61377084)Science Fund for Distinguished Young Scholars of Harbin(RC2016JQ006007)
文摘The spectral purity of fiber lasers has become a critical issue in both optical sensing and communication fields.As a result of ultra-narrow intrinsic linewidth, stimulated thermal Rayleigh scattering(STRS) has presented special potential to compress the linewidth of fiber lasers. To suppress stimulated Brillouin scattering(SBS), the most dominant disturbance for STRS in optical fibers, a semi-quantitative estimation has been established to illuminate the mechanism of suppressing SBS in a periodic tapered fiber, and it agrees with experimental results. Finally, a linewidth compression device based on STRS is integrated into a single-longitudinal-mode ring-cavity fiber laser with secondary cavities, and its linewidth is verified to be 200 Hz through a self-heterodyne detecting and Voigt fitting method.
基金Project supported by the National Natural Science Foundation of China(No.61975046)。
文摘Finding the optimal optoelectronic properties(zero-order optical transmittance,shielding effectiveness,and stray light uniformity)of metallic mesh is significant for its application in electromagnetic interference shielding areas.However,there are few relevant studies at present.Based on optoelectronic properties,we propose a comprehensive evaluation factor Q,which is simple in form and can be used to evaluate the mesh with different parameters in a simple and efficient way.The effectivity of Q is verified by comparing the trend of Q values with the evaluation results of the technique for order preference by similarity to ideal solution(TOPSIS).The evaluation factor Q can also be extended to evaluate the optoelectronic properties of different kinds of metallic meshes,which makes it extremely favorable for metallic mesh design and application.
基金This work was supported by the Postdoctoral Science Foundation(Nos.BX20490103,2020M681089,LBH-Z19065 and LBHZ13109)the National Natural Science Foundation of China(No.52002093).
文摘Textured BaTiO_(3)(BT)-based lead-free ceramics have gained significant attention due to their high piezoelectric coefficient(d)and very large field induced strain(S).However,costly nano-size raw materials,excessively high sintering temperature and low Curie temperature(T_(c))hinder their device applications.In this work,highly[001]_(c)-oriented(Ba_(0.95)Ca_(0.05))(Zr_(0.04)Ti_(0.96))O_(3) ceramics with x mol%CuO(x=0.25,0.5,1.0,2.5)denoted as BCZT-x were synthesized by templated grain growth using micro-sized raw powders.The introduction of CuO sintering agent lowered the sintering temperature by 125℃ to 1450℃,and the BCZT-1.0 achieved a high texture degree of∼99%.In addition,the CuO-based liquid phases eliminated boundaries between BT templates and BCZT matrix powders.Such liquid-phase sintering reduced sintering stresses,decreased the average grain size of BCZT-1.0 from 16μm down to 13μm,and increased the dielectric dispersion coefficientγto 1.63.The almost smoothed out T_(O-T) anomaly in the temperature dependence of dielectric permittivity and comparably high T_(c)(>102℃)lead to better temperature stability.The narrower grain orientation distribution with full width at half maximum(FWHM)of∼5.9°and smaller domains with the size of 0.1–0.5μm in width and 3–8μm in length were obtained,a high field induced maximum strain S_(max) of 0.38%and low H_(s) of 5.2%have been achieved in BCZT-1.0 textured ceramics together with a high and homogeneous piezoelectric stress coefficient d_(33)∼780 pC/N and very large d_(33)∗∼2950 pm/V.
基金This work was funded by the National Natural Science Foundation of China(Grant No.51675136)the National Science and Technology Major Project(Grant No.2017ZX02101006-005)+1 种基金the China Postdoctoral Science Foundation(Grant No.2018T110291)the Heilongjiang Natural Science Foundation(Grant No.E2017032).
文摘This paper presents a dynamic and static error transfer model and uncertainty evaluation method for a high-speed variable-slit system based on a two- dimensional orthogonal double-layer air-floating guide rail structure. The motion accuracy of the scanning blade is affected by both the moving component it is attached to and the moving component of the following blade during high-speed motion. First, an error transfer model of the high-speed variable-slit system is established, and the influence coefficients are calculated for each source of error associated with the accuracy of the blade motion. Then, the maximum range of each error source is determined by simulation and experiment. Finally, the uncertainty of the blade displacement measurement is evaluated using the Monte Carlo method. The proposed model can evaluate the performance of the complex mechanical system and be used to guide the design.
基金Project supported by the National Natural Science Foundation of China(No.51975160)。
文摘In the semiconductor manufacturing industry,the dynamic model of a controlled object is usually obtained from a frequency sweeping method before motion control.However,the existing isolators cannot properly isolate the disturbance of the inertial force on the platform base during frequency sweeping(the frequency is between 0 Hz and the natural frequency).In this paper,an adjustable anti-resonance frequency controller for a dual-stage actuation semi-active vibration isolation system(DSASAVIS)is proposed.This system has a significant anti-resonance characteristic;that is,the vibration amplitude can drop to nearly zero at a particular frequency,which is called the anti-resonance frequency.The proposed controller is designed to add an adjustable anti-resonance frequency to fully use this unique anti-resonance characteristic.Experimental results show that the closed-loop transmissibility is less than−15 dB from 0 Hz to the initial anti-resonance frequency.Furthermore,it is less than−30 dB around an added anti-resonance frequency which can be adjusted from 0 Hz to the initial anti-resonance frequency by changing the parameters of the proposed controller.With the proposed controller,the disturbance amplitude of the payload decays from 4 to 0.5 mm/s with a reduction of 87.5%for the impulse disturbance applied to the platform base.Simultaneously,the system can adjust the anti-resonance frequency point in real time by tracking the frequency sweeping disturbances,and a good vibration isolation performance is achieved.This indicates that the DSA-SAVIS and the proposed controller can be applied in the guarantee of an ultra-low vibration environment,especially at frequency sweeping in the semiconductor manufacturing industry.
基金Project supported by the the National Major Science and Technology Projects of China(No.2017ZX02101006-005)。
文摘Representation of orientation is important in a six-degree-of-freedom grating interferometer but only a few studies have focused on this topic.Roll-pitch-yaw angles,widely used in aviation,navigation,and robotics,are now being brought to the field of multi-degree-of-freedom interferometric measurement.However,the roll-pitch-yaw angles are not the exact definitions the metrologists expected in interferometry,because they require a certain sequential order of rotations and may cause errors in describing complicated rotations.The errors increase as the tip and tilt angles of the grating increase.Therefore,a replacement based on fused angles in robotics is proposed and named“fused-like angles.”The fused-like angles are error-free,so they are more in line with the definitions in grating interferometry and more suitable for six-degree-of-freedom measurements.Fused-like angles have already been used in research on the kinematic model and decoupling algorithm of the six-degree-of-freedom grating interferometer.
基金National Natural Science Foundation of China(52061135114)National Major Science and Technology Projects of China (2017ZX02101006-005)。
文摘We propose a precision phase-generated-carrier(PGC) demodulation method with sub-nanometer resolution that avoids nonlinear errors in a laser wavelength sinusoidal modulation fiber-optic interferometer for long range dynamic displacement sensing.Using orthogonal detection and an AC-DC component extraction scheme,the PGC carrier phase delay(CPD) and laser intensity modulation phase delay can be obtained simultaneously to eliminate the nonlinear error from accompanied optical intensity modulation and CPD.Further,to realize long range displacement sensing,PGC phase modulation depth(PMD),determined by the laser wavelength modulation amplitude and the working distance of the interferometer,is required to maintain an optimal value during measurement,including initial position and dynamic movement.By combining frequency sweeping interference and modified PGC-arctan demodulation to measure real-time working distance,adaptive PMD technology is realized based on proportion control.We construct a fiber-optic Michelson and SIOS commercial interferometer for comparison and perform experiments to verify the feasibility of the proposed method.Experimental results demonstrate that an interferometer with sub-nanometer resolution and nanometer precision over a large range of 400 mm can be realized.
