For space-borne gravitational wave detection missions based on the heterodyne interferometry principle,tilt-to-length(TTL)coupling noise is an important optical noise source,significantly influencing the accuracy of t...For space-borne gravitational wave detection missions based on the heterodyne interferometry principle,tilt-to-length(TTL)coupling noise is an important optical noise source,significantly influencing the accuracy of the measurement system.We present a method for analyzing TTL coupling noise under the joint influence of multiple factors.An equivalent simulated optical bench for the test mass interferometer was designed,and Gaussian beam tracing was adopted to simulate beam propagation.By simulating the interference signal,it can analyze the impact of various factors on the TTL coupling noise,including positional,beam parameters,detector parameters,and signal definition factors.On this basis,a random parameter space composed of multiple influential factors was constructed within a range satisfying the analysis requirement,and the corresponding simulation results from random sampling were evaluated via variance-based global sensitivity analysis.The calculated results of the main and total effect indexes show that the test mass rotation angle and the piston effect(lateral)significantly influence the TTL coupling noise in the test mass interferometer.The analysis provides a qualitative reference for designing and optimizing space-borne laser interferometry systems.展开更多
Acoustic detection has many applications across science and technology from medicine to imaging and communications.However,most acoustic sensors have a common limitation in that the detection must be near the acoustic...Acoustic detection has many applications across science and technology from medicine to imaging and communications.However,most acoustic sensors have a common limitation in that the detection must be near the acoustic source.Alternatively,laser interferometry with picometer-scale motional displacement detection can rapidly and precisely measure sound-induced minute vibrations on remote surfaces.Here,we demonstrate the feasibility of sound detection up to 100 kHz at remote sites with≈60 m optical path length via laser homodyne interferometry.Based on our ultrastable hertz linewidth laser with 10-15 fractional stability,our laser interferometer achieves 0.5 pm/Hz1/2 displacement sensitivity near 10 kHz,bounded only by laser frequency noise over 10 kHz.Between 140 Hz and 15 kHz,we achieve a homodyne acoustic sensing sensitivity of subnanometer/Pascal across our conversational frequency overtones.The minimal sound pressure detectable over 60 m optical path length is≈2 mPa,with dynamic ranges over 100 dB.With the demonstrated standoff picometric distance metrology,we successfully detected and reconstructed musical scores of normal conversational volumes with high fidelity.The acoustic detection via this precision laser interferometer could be applied to selective area sound sensing for remote acoustic metrology,optomechanical vibrational motion sensing,and ultrasensitive optical microphones at the laser frequency noise limits.展开更多
Population growth leads to increased utilization of water resources.One of these resources is groundwater,which has steadily declined each year.The depletion of these resources brings about various environmental chall...Population growth leads to increased utilization of water resources.One of these resources is groundwater,which has steadily declined each year.The depletion of these resources brings about various environmental challenges.The present study aimed to explore the relationship between groundwater fluctuations and land subsidence in the Malayer Plain,Iran,focusing on quantifying subsidence resulting from groundwater extraction.Using Sentinel-1 satellite data(2014–2019)and monthly piezometric measurements(1996–2018),the analysis revealed an average deformation velocity of–6.3 cm yr–1,with accumulated subsidence of–32 cm over the 2014–2019 period.The maximum subsidence rate reached 10.3 cm yr–1 in areas of intensive agricultural activity.A wavelet-PCA spatiotemporal analysis of groundwater fluctuations identified critical multi-scale patterns strongly correlated with subsidence trends.Regression analysis between subsidence rates and groundwater fluctuations at various wavelet decomposition levels explained 75%of the variance(R2=0.75),indicating that intermediate-scale groundwater declines were the primary drivers of subsidence.Furthermore,land use analysis using Landsat data(1999–2021)revealed a 6230-ha increase in irrigated farmland,contributing to heightened groundwater extraction and subsidence rates.These findings highlight the critical need for sustainable groundwater management to mitigate the risks of continued subsidence in the region.展开更多
The thickness and upper densification structure of an ice sheet are important parameters for dynamic ice sheet modeling and glacier mass balance studies.Seismic ambient noise methods,such as the horizontal-to-vertical...The thickness and upper densification structure of an ice sheet are important parameters for dynamic ice sheet modeling and glacier mass balance studies.Seismic ambient noise methods,such as the horizontal-to-vertical spectral ratio(H/V)method and ambient noise cross-correlation method,are becoming increasingly popular in glacier structure investigations.During China's 39th expedition to Antarctica,seismic ambient noise experiments were conducted to investigate the structure of the ice sheet at Kunlun Station,Dome A,using a seismic nodal system.We obtained a broad band(0.1–10 Hz)H/V curve with a 1-hour noise record from a seismic node.In addition,we extracted the Rayleigh wave dispersion curve with 5-day noise cross-correlation functions from a linear dense seismic array.Three clear peaks were observed in the H/V curve—a lower peak at~0.17 Hz and two higher frequency peaks at~3 Hz and~6 Hz.We inverted the ice sheet thickness using the lower frequency portion of the H/V curve and inverted the upper structure of the ice sheet using the higher frequency portion of the H/V curve jointly with the dispersion curve.Our estimations from ambient noise observations were consistent with those derived from the BedMachine ice sheet thickness dataset and the density profile determined by ground-penetrating radar investigations at the same site.展开更多
Null compensation interferometry is the primary testing method for the manufacture of ultra-high-precision aspheric mirrors.The crosstalk fringes generated by stray light in interferometry can affect accuracy and pote...Null compensation interferometry is the primary testing method for the manufacture of ultra-high-precision aspheric mirrors.The crosstalk fringes generated by stray light in interferometry can affect accuracy and potentially prevent the testing from proceeding normally.Position errors include the decenter error,tilt error,and distance error.During the testing process,position errors will impact the testing accuracy and the crosstalk fringes generated by stray light.To determine the specific impact of position errors,we use the concept of Hindle shell testing of a convex aspheric mirror,and propose the simulation method of crosstalk fringes in null compensation interferometry.We also propose evaluation indices of crosstalk fringes in interferometry and simulate the influence of position errors on the crosstalk fringes.This work aims to help improve the design of compensation interferometry schemes,enhance the feasibility of the design,reduce engineering risks,and improve efficiency.展开更多
A case study of seismic interferometry applied to a small microseismic monitoring network is here presented.The main objectives of this study are(i)to quantify the lateral variability of shear-wave ve-locities in the ...A case study of seismic interferometry applied to a small microseismic monitoring network is here presented.The main objectives of this study are(i)to quantify the lateral variability of shear-wave ve-locities in the studied area,and(ii)to investigate the bias produced by noise directionality and non-stationarity in the velocity estimate.Despite the limited number of stations and the short-period char-acter of the seismic sensors,the empirical Green's functions were retrieved for all station pairs using two years of passive data.Both group and phase velocities were derived,the former using the widespread frequency-time analysis,the latter through the analysis of the real part of the cross-spectra.The main advantage of combining these two methods is a more accurate identification of higher modes,resulting in a reduction of ambiguity during picking and data interpretation.Surface wave tomography was run to obtain the spatial distribution of group and phase velocities for the same wavelengths.The low standard deviation of the results suggests that the sparse character of the network does not limit the applicability of the method,for this specific case.The obtained maps highlight the presence of a lower velocity area that extends from the centre of the network towards southeast.Group and phase velocity dispersion curves have been jointly inverted to retrieve as many shear-wave velocity profiles as selected station pairs.While the average model can be used for a more accurate location of the local natural seismicity,the associated standard deviations give us an indication of the lateral heterogeneity of seismic velocities as a function of depth.Finally,the same velocity analysis was repeated for different time windows in order to quantify the error associated to variations in the noise field.Errors as large as 4%have been found,related to the unfavorable orientation of the receiver pairs with respect to strongly directional noise sources,and to the very short time widows.It was shown that using a one-year time window these errors arereduced to 0.3%.展开更多
Laser frequency microcombs provide a series of equidistant,coherent frequency markers across a broad spectrum,enabling advancements in laser spectroscopy,dense optical communications,precision distance metrology,and a...Laser frequency microcombs provide a series of equidistant,coherent frequency markers across a broad spectrum,enabling advancements in laser spectroscopy,dense optical communications,precision distance metrology,and astronomy.Here,we design and fabricate silicon nitride,dispersion-managed microresonators that effectively suppress avoided-mode crossings and achieve close-to-zero averaged dispersion.Both the stochastic noise and mode-locking dynamics of the resonator are numerically and experimentally investigated.First,we experimentally demonstrate thermally stabilized microcomb formation in the microresonator across different mode-locked states,showing negligible center frequency shifts and a broad frequency bandwidth.Next,we characterize the femtosecond timing jitter of the microcombs,supported by precise metrology of the timing phase and relative intensity noise.For the single-soliton state,we report a relative intensity noise of−153.2 dB∕Hz,close to the shot-noise limit,and a quantum-noise–limited timing jitter power spectral density of 0.4 as 2∕Hz at a 100 kHz offset frequency,measured using a self-heterodyne linear interferometer.In addition,we achieve an integrated timing jitter of 1.7 fs±0.07 fs,measured from 10 kHz to 1 MHz.Measuring and understanding these fundamental noise parameters in high clock rate frequency microcombs is critical for advancing soliton physics and enabling new applications in precision metrology.展开更多
Dense-array ambient noise tomography is a powerful tool for achieving high-resolution subsurface imag-ing,significantly impacting geohazard prevention and control.Conventional dense-array studies,how-ever,require simu...Dense-array ambient noise tomography is a powerful tool for achieving high-resolution subsurface imag-ing,significantly impacting geohazard prevention and control.Conventional dense-array studies,how-ever,require simultaneous observations of numerous stations for extensive coverage.To conduct a comprehensive karst feature investigation with limited stations,we designed a new synchronous-asyn-chronous observation system that facilitates dense array observations.We conducted two rounds of asynchronous observations,each lasting approximately 24 h,in combination with synchronous backbone stations.We achieved wide-ranging coverage of the study area utilizing 197 nodal receivers,with an average station spacing of 7 m.The beamforming results revealed distinct variations in the noise source distributions between day and night.We estimated the source strength in the stationary phase zone and used a weighting scheme for stacking the cross-correlation functions(C ^(1) functions)to suppress the influ-ence of nonuniform noise source distributions.The weights were derived from the similarity coefficients between multicomponent C^(1)functions related to Rayleigh waves.We employed the cross-correlation of C ^(1) functions(C^(2)methods)to obtain the empirical Green’s functions between asynchronous stations.To eliminate artifacts in C ^(2) functions from higher-mode surface waves in C^(1)functions,we filtered the C^(1)functions on the basis of different particle motions linked to multimode Rayleigh waves.The dispersion measurements of Rayleigh waves obtained from both the C^(1)and C^(2)functions were utilized in surface wave tomography.The inverted three-dimensional(3D)shear-wave(S-wave)velocity model reveals two significant low-velocity zones at depths ranging from 40 to 60 m,which align well with the karst caves found in the drilling data.The method of short-term synchronous-asynchronous ambient noise tomography shows promise as a cost-effective and efficient approach for urban geohazard investigations.展开更多
Single-wavelength interferometry achieves high resolution for smooth surfaces but struggles with rough industrially relevant ones due to limited unambiguous measuring range and speckle effects.Multiwavelength interfer...Single-wavelength interferometry achieves high resolution for smooth surfaces but struggles with rough industrially relevant ones due to limited unambiguous measuring range and speckle effects.Multiwavelength interferometry addresses these challenges using synthetic wavelengths,enabling a balance between extended measurement range and resolution by combining several synthetic wavelengths.This approach holds immense potential for diverse industrial applications,yet it remains largely untapped due to the lack of suitable light sources.Existing solutions are constrained by limited flexibility in synthetic-wavelength generation and slow switching speeds.We demonstrate a light source for multiwavelength interferometry based on electro-optic single-sideband modulation.It reliably generates synthetic wavelengths with arbitrary values from centimeters to meters and switching time below 30 ms.This breakthrough paves the way for dynamic reconfigurable multiwavelength interferometry capable of adapting to complex surfaces and operating efficiently even outside laboratory settings.These capabilities unlock the full potential of multiwavelength interferometry,offering unprecedented flexibility and speed for industrial and technological applications.展开更多
Laser interferometry with higher resolution,faster update rate,and larger dynamic range is highly anticipated in the exploration of physics frontiers,advanced manufacturing,and precision sensing.Real-time dispersive s...Laser interferometry with higher resolution,faster update rate,and larger dynamic range is highly anticipated in the exploration of physics frontiers,advanced manufacturing,and precision sensing.Real-time dispersive spectral interferometry(DSI)shows promise for high-speed precision measurements,whereas the resolution of subnanometers has not yet been achieved.We present a comprehensive theoretical framework to analyze the limitations of real-time DSI based on the signal-to-noise ratio and data volume.A real-time orthogonal polarization spectral interferometry technique is proposed,which utilizes a pair of interferograms with the pi-phase shift to effectively mitigate the phase noise embedded in real-time spectral envelopes,thereby enabling the precise measurements with subnanometer resolution at megahertz frame rates.The recorded time series data are processed through interpolation,segmentation,time–frequency mapping,and de-enveloping to regain the typical cosine-shaped spectral evolution,followed by a fitting-based phase retrieval method to extract the interference phase.The phase resolution of 1.1 mrad(0.91 as for time delay and 0.3 nm for distance)is obtained at the update rate of 22.2 MHz even under the detection bandwidth of 500 MHz,and can be further enhanced to 0.29 mrad(0.24 as for time delay)after 500 times averaging(∼0.5 MHz).Our approach is validated through periodic phase modulations and applied to measure the rapid damped oscillations of a piezo stage,yielding results consistent with those obtained from a commercial picometer interferometer.展开更多
Studying the inner structure of intraplate earthquakes originating in aseismic areas,which are poorly covered by seismic networks or as historical earthquakes is usually the only way to get knowledge about their sourc...Studying the inner structure of intraplate earthquakes originating in aseismic areas,which are poorly covered by seismic networks or as historical earthquakes is usually the only way to get knowledge about their source mechanisms,which is partially essential for a deeper understanding of intraplate geodynamics.The epicentral zones of earthquakes are situated in hard-toreach areas,so,using active seismic methods for such purposes is unreasonable or even impossible because of high cost and logistical difficulties.We propose a novel approach that combines diverse passive seismic methods,which allows us to get sufficient information about geological environment structure for such task solutions.As an example,we investigated the inner structure of platform earthquake epicentral zone originated up north of Russia.We used four passive seismic methods:microseismic sounding method,passive seismic interferometry,HVSR method,and microseismic activity method.We show that passive seismic data,recoded in the same installation and processed by these different methods,can provide sufficient information about structure of studied environment,needed to explain source mechanism.In sum,the hypocenter zone is presented by intersection of vertical faults and a lateral fractured zone in the middle crust.Results were confirmed by comparison with results by active seismic methods.展开更多
Understanding rock behavior is crucial in mine geotechnical engineering to ensure construction efficiency,mitigate rock-related hazards,and promote environmental sustainability.Coda Wave Interferometry(CWI),a non-dest...Understanding rock behavior is crucial in mine geotechnical engineering to ensure construction efficiency,mitigate rock-related hazards,and promote environmental sustainability.Coda Wave Interferometry(CWI),a non-destructive ultrasonic testing method,has been widely employed to assess micro-damage evolution in rocks induced by perturbations in scatterer position,velocity,or source location due to its exceptional sensitivity.However,challenges persist in evaluating cross-scale rock behavior influenced by nonlinear deformation and multi-field interactions under multiple coupled perturbations.A comprehensive review of the perturbation factors affecting rock damage evolution and potential failure mechanisms is essential for presenting available knowledge in a more systematic and structured manner.This review provides an in-depth analysis of the CWI technique,encompassing its origins,theoretical framework,and classical data processing methodologies.Additionally,it explores the diverse applications of CWI in assessing rock behavior under various perturbation factors,including temperature variations,fluid infiltration,and stress conditions,with a particular emphasis on nonlinear deformation and multi-field coupling effects.Furthermore,a novel method for calculating relative velocity changes in coda waves is introduced,enabling a more precise characterization of the entire rock failure process.The study also proposes a cutting-edge concept of ultra-early and refined monitoring and warning technology for mine rock disasters,leveraging the advancements in CWI.Finally,the review highlights the potential future developments of CWI in high-level intelligent mining scenarios,particularly its integration with ambient noise interferometry and microseismic coda wave analysis.This work serves as a valuable reference,contributing to the refinement of CWI applications for assessing complex rock behavior and enhancing the accuracy of rock disaster prediction and early warning systems.展开更多
Laser frequency combs,which are composed of a series of equally spaced coherent frequency components,have triggered revolutionary progress in precision spectroscopy and optical metrology.Length/distance is of fundamen...Laser frequency combs,which are composed of a series of equally spaced coherent frequency components,have triggered revolutionary progress in precision spectroscopy and optical metrology.Length/distance is of fundamental importance in both science and technology.We describe a ranging scheme based on chirped pulse interferometry.In contrast to the traditional spectral interferometry,the local oscillator is strongly chirped which is able to meet the measurement pulses at arbitrary distances,and therefore,the dead zones can be removed.The distances can be precisely determined via two measurement steps based on the time-of-flight method and synthetic wavelength interferometry,respectively.To overcome the speed limitation of the optical spectrum analyzer,the spectrograms are stretched and detected by a fast photodetector and oscilloscope and consequently mapped into the time domain in real time.The experimental results indicate that the measurement uncertainty can be well within±2μm,compared with the reference distance meter.The Allan deviation can reach 0.4μm at 4 ns averaging time and 25 nm at 1μs and can achieve 2 nm at 100μs averaging time.We also measured a spinning disk with grooves of different depths to verify the measurement speed,and the results show that the grooves with about 150 m∕s line speed can be clearly captured.Our method provides a unique combination of non-dead zones,ultrafast measurement speed,high precision and accuracy,large ambiguity range,and only one single comb source.This system could offer a powerful solution for field measurements in practical applications in the future.展开更多
In common practice in the oil fields,the injection of water and gas into reservoirs is a crucial technique to increase production.The control of the waterflooding front in oil/gas exploitation is a matter of great con...In common practice in the oil fields,the injection of water and gas into reservoirs is a crucial technique to increase production.The control of the waterflooding front in oil/gas exploitation is a matter of great concern to reservoir engineers.Monitoring the waterflooding front in oil/gas wells plays a very important role in adjusting the well network and later in production,taking advantage of the remaining oil po-tential and ultimately achieving great success in improving the recovery rate.For a long time,micro-seismic monitoring,numerical simulation,four-dimensional seismic and other methods have been widely used in waterflooding front monitoring.However,reconciling their reliability and cost poses a significant challenge.In order to achieve real-time,reliable and cost-effective monitoring,we propose an innovative method for waterflooding front monitoring through the similarity analysis of passive source time-lapse seismic images.Typically,passive source seismic data collected from oil fields have extremely low signal-to-noise ratio(SNR),which poses a serious problem for obtaining structural images.The proposed method aims to visualize and analyze underground changes by highlighting time-lapse images and provide a strategy for underground monitoring using long-term passive source data under low SNR conditions.First,we verify the feasibility of the proposed method by designing a theoretical model.Then,we conduct an analysis of the correlation coefficient(similarity)on the passive source time-lapse seismic imaging results to enhance the image differences and identify the simulated waterflooding fronts.Finally,the proposed method is applied to the actual waterflooding front monitoring tasks in Shengli Oilfield,China.The research findings indicate that the monitoring results are consistent with the actual devel-opment conditions,which in turn demonstrates that the proposed method has great potential for practical application and is very suitable for monitoring common development tasks in oil fields.展开更多
Passive surface wave imaging has been a powerful tool for near-surface characterization in urban areas,which extracts surface wave signals from ambient seismic noise and then estimates subsurface shear wave velocity b...Passive surface wave imaging has been a powerful tool for near-surface characterization in urban areas,which extracts surface wave signals from ambient seismic noise and then estimates subsurface shear wave velocity by inversion of the measured phase velocity.The high-frequency(approximately>1 Hz)seismic noise fields in urban environments are dominantly induced by human activities such as the vehicle traffic.Traffic seismic sources are nonrandomly distributed in time and space.Applying standard interferometric techniques to recordings from these nonrandom noise sources makes the Green’s function liable to estimation errors.We analyze the influence of using nonrandom traffic seismic sources for surface wave imaging.With nonrandom traffic seismic sources in time,spurious signals are generated in the cross-correlation function.With nonrandom traffic seismic sources in space,surface-wave phase velocities could be overestimated in the dispersion measurement.We provide an overview of solutions for surface-wave imaging with nonrandom traffic seismic sources in time and space,aiming to improve the retrieval of high-frequency surface waves and achieve reliable results from ultrashort(tens of seconds)observations for near-surface characterization.展开更多
We propose a quantum-enhanced metrological scheme utilizing unbalanced entangled coherent states(ECSs) generated by passing a coherent state and a coherent state superposition through an unbalanced beam splitter(BS). ...We propose a quantum-enhanced metrological scheme utilizing unbalanced entangled coherent states(ECSs) generated by passing a coherent state and a coherent state superposition through an unbalanced beam splitter(BS). We identify the optimal phase sensitivity of this scheme by maximizing the quantum Fisher information(QFI) with respect to the BS transmission ratio. Our scheme outperforms the conventional scheme with a balanced BS, particularly in the presence of single-mode photon loss. Notably, our scheme retains quantum advantage in phase sensitivity in the limit of high photon intensity, where the balanced scheme offers no advantage over the classical strategy.展开更多
The semiconductor bridge(SCB)ignites through bridge film discharge,offering advantages such as low ignition energy,high safety,and compatibility with digital logic circuits.The study uses laser interferometry to inves...The semiconductor bridge(SCB)ignites through bridge film discharge,offering advantages such as low ignition energy,high safety,and compatibility with digital logic circuits.The study uses laser interferometry to investigate the gas dynamics of the bridge film after SCB plasma extinction.Interferometric images of the SCB film gas were obtained through a laser interferometry optical path.After the degradation model of digital image processing,clearer images were produced to facilitate analysis and calculation.The results show that the gas temperature at the center of the SCB film reaches a maximum of 1000 K,and the temperature rapidly decreases along the axial direction of the bridge surface to room temperature at 300 K.The maximum diffusion velocity of the plasma is 1.8 km/s.These findings provide critical insights for SCB design and ignition control.展开更多
The taste presentation and receptor perception mechanism of the salty peptide of Stropharia rugosoannulata were predicted and verified using peptide omics and molecular interaction techniques.The combination of aspart...The taste presentation and receptor perception mechanism of the salty peptide of Stropharia rugosoannulata were predicted and verified using peptide omics and molecular interaction techniques.The combination of aspartic acid(D)and glutamic acid(E),or peptide fragments composed of arginine(R),constitute the characteristic taste structural basis of salty peptides of S.rugosoannulata.The taste intensity of the salty peptide positively correlates with its concentration within a specific concentration range(0.25–1.0 mg/mL).The receptor more easily recognizes the first amino acid residue at the N-terminal of salty peptides and the aspartic acid residue in the peptides.GLU513,ASP707,and VAL508 are the critical amino acid residues for the receptor to recognize salty peptides.TRPV1 is specifically the receptor for recognizing salty peptides.Hydrogen bonds and electrostatic interactions are the main driving forces for the interactions between salty peptides and TRPV1 receptors.KSWDDFFTR has the most potent binding capacity with the receptor and has tremendous potential for application in sodium salt substitution.This study confirmed the taste receptor that specifically recognizes salty peptides,analyzed the receptor-peptide binding interaction,and provided a new idea for understanding the taste receptor perception of salty peptides.展开更多
We propose pattern self-referenced single-pixel common-path holography(PSSCH),which can be realized using either the digital-micromirror-device(DMD)based off-axis scheme or the DMD-based phaseshifting approach,sharing...We propose pattern self-referenced single-pixel common-path holography(PSSCH),which can be realized using either the digital-micromirror-device(DMD)based off-axis scheme or the DMD-based phaseshifting approach,sharing the same experimental setup,to do wavefront reconstructions.In this method,each modulation pattern is elaborately encoded to be utilized to not only sample the target wavefront but also to dynamically introduce the reference light for single-pixel common-path holographic detection.As such,it does not need to intentionally introduce a static reference light,resulting in it making full use of the pixel resolution of the modulation patterns and suppressing dynamically varying noises.Experimental demonstrations show that the proposed method can not only obtain a larger field of view than the peripheral-referenced approach but also achieve a higher imaging resolution than the checkerboardreferenced approach.The phase-shifting-based PSSCH performs better than the off-axis-based PSSCH on imaging fidelity,while the imaging speed of the latter is several times faster.Further,we demonstrate our method to do wavefront imaging of a biological sample as well as to do phase detection of a physical lens.The experimental results suggest its effectiveness in applications.展开更多
We present a unified electromagnetic modeling of coherence scanning interferometry,confocal microscopy,and focus variation microscopy as the most common techniques for surface topography inspection with micro-and nano...We present a unified electromagnetic modeling of coherence scanning interferometry,confocal microscopy,and focus variation microscopy as the most common techniques for surface topography inspection with micro-and nanometer resolution.The model aims at analyzing the instrument response and predicting systematic deviations.Since the main focus lies on the modeling of the microscopes,the light–surface interaction is considered,based on the Kirchhoff approximation extended to vectorial imaging theory.However,it can be replaced by rigorous methods without changing the microscope model.We demonstrate that all of the measuring instruments mentioned above can be modeled using the same theory with some adaption to the respective instrument.For validation,simulated results are confirmed by comparison with measurement results.展开更多
文摘For space-borne gravitational wave detection missions based on the heterodyne interferometry principle,tilt-to-length(TTL)coupling noise is an important optical noise source,significantly influencing the accuracy of the measurement system.We present a method for analyzing TTL coupling noise under the joint influence of multiple factors.An equivalent simulated optical bench for the test mass interferometer was designed,and Gaussian beam tracing was adopted to simulate beam propagation.By simulating the interference signal,it can analyze the impact of various factors on the TTL coupling noise,including positional,beam parameters,detector parameters,and signal definition factors.On this basis,a random parameter space composed of multiple influential factors was constructed within a range satisfying the analysis requirement,and the corresponding simulation results from random sampling were evaluated via variance-based global sensitivity analysis.The calculated results of the main and total effect indexes show that the test mass rotation angle and the piston effect(lateral)significantly influence the TTL coupling noise in the test mass interferometer.The analysis provides a qualitative reference for designing and optimizing space-borne laser interferometry systems.
基金supported by the Office of Naval Research(Grant Nos.N00014-16-1-2094 and N00014-24-1-2547)the Lawrence Livermore National Laboratory(Grant No.B622827)the National Science Foundation.Y.-S.J.acknowledges support from KRISS(Grant Nos.25011026 and 25011211).
文摘Acoustic detection has many applications across science and technology from medicine to imaging and communications.However,most acoustic sensors have a common limitation in that the detection must be near the acoustic source.Alternatively,laser interferometry with picometer-scale motional displacement detection can rapidly and precisely measure sound-induced minute vibrations on remote surfaces.Here,we demonstrate the feasibility of sound detection up to 100 kHz at remote sites with≈60 m optical path length via laser homodyne interferometry.Based on our ultrastable hertz linewidth laser with 10-15 fractional stability,our laser interferometer achieves 0.5 pm/Hz1/2 displacement sensitivity near 10 kHz,bounded only by laser frequency noise over 10 kHz.Between 140 Hz and 15 kHz,we achieve a homodyne acoustic sensing sensitivity of subnanometer/Pascal across our conversational frequency overtones.The minimal sound pressure detectable over 60 m optical path length is≈2 mPa,with dynamic ranges over 100 dB.With the demonstrated standoff picometric distance metrology,we successfully detected and reconstructed musical scores of normal conversational volumes with high fidelity.The acoustic detection via this precision laser interferometer could be applied to selective area sound sensing for remote acoustic metrology,optomechanical vibrational motion sensing,and ultrasensitive optical microphones at the laser frequency noise limits.
文摘Population growth leads to increased utilization of water resources.One of these resources is groundwater,which has steadily declined each year.The depletion of these resources brings about various environmental challenges.The present study aimed to explore the relationship between groundwater fluctuations and land subsidence in the Malayer Plain,Iran,focusing on quantifying subsidence resulting from groundwater extraction.Using Sentinel-1 satellite data(2014–2019)and monthly piezometric measurements(1996–2018),the analysis revealed an average deformation velocity of–6.3 cm yr–1,with accumulated subsidence of–32 cm over the 2014–2019 period.The maximum subsidence rate reached 10.3 cm yr–1 in areas of intensive agricultural activity.A wavelet-PCA spatiotemporal analysis of groundwater fluctuations identified critical multi-scale patterns strongly correlated with subsidence trends.Regression analysis between subsidence rates and groundwater fluctuations at various wavelet decomposition levels explained 75%of the variance(R2=0.75),indicating that intermediate-scale groundwater declines were the primary drivers of subsidence.Furthermore,land use analysis using Landsat data(1999–2021)revealed a 6230-ha increase in irrigated farmland,contributing to heightened groundwater extraction and subsidence rates.These findings highlight the critical need for sustainable groundwater management to mitigate the risks of continued subsidence in the region.
基金supported by the National Natural Science Foundation of China(NSFC),grant number 42076234the National Key Research and Development Program of China,grant number 2021YFC2801404。
文摘The thickness and upper densification structure of an ice sheet are important parameters for dynamic ice sheet modeling and glacier mass balance studies.Seismic ambient noise methods,such as the horizontal-to-vertical spectral ratio(H/V)method and ambient noise cross-correlation method,are becoming increasingly popular in glacier structure investigations.During China's 39th expedition to Antarctica,seismic ambient noise experiments were conducted to investigate the structure of the ice sheet at Kunlun Station,Dome A,using a seismic nodal system.We obtained a broad band(0.1–10 Hz)H/V curve with a 1-hour noise record from a seismic node.In addition,we extracted the Rayleigh wave dispersion curve with 5-day noise cross-correlation functions from a linear dense seismic array.Three clear peaks were observed in the H/V curve—a lower peak at~0.17 Hz and two higher frequency peaks at~3 Hz and~6 Hz.We inverted the ice sheet thickness using the lower frequency portion of the H/V curve and inverted the upper structure of the ice sheet using the higher frequency portion of the H/V curve jointly with the dispersion curve.Our estimations from ambient noise observations were consistent with those derived from the BedMachine ice sheet thickness dataset and the density profile determined by ground-penetrating radar investigations at the same site.
基金the National Key Research and Development Program of China(2022YFB3403404)the Youth Innovation Promotion Association,CAS(2022213)the National Natural Science Foundation of China(62127901 and 62305334).
文摘Null compensation interferometry is the primary testing method for the manufacture of ultra-high-precision aspheric mirrors.The crosstalk fringes generated by stray light in interferometry can affect accuracy and potentially prevent the testing from proceeding normally.Position errors include the decenter error,tilt error,and distance error.During the testing process,position errors will impact the testing accuracy and the crosstalk fringes generated by stray light.To determine the specific impact of position errors,we use the concept of Hindle shell testing of a convex aspheric mirror,and propose the simulation method of crosstalk fringes in null compensation interferometry.We also propose evaluation indices of crosstalk fringes in interferometry and simulate the influence of position errors on the crosstalk fringes.This work aims to help improve the design of compensation interferometry schemes,enhance the feasibility of the design,reduce engineering risks,and improve efficiency.
基金This study is part of the project 2021RUAPON-REACT EU-Finanziamento PON“Ricerca e Innovazione”20142020,grant n.19-G-12543-2,funded by the Italian Ministry of University and Research(MUR)This study was developed in the frame of“The Geosciences for Sustainable Development”project(Budget Minis-tero dell'Universita e della Ricerca-Dipartimenti di Eccellenza 2023-2027,code n.C93C23002690001).
文摘A case study of seismic interferometry applied to a small microseismic monitoring network is here presented.The main objectives of this study are(i)to quantify the lateral variability of shear-wave ve-locities in the studied area,and(ii)to investigate the bias produced by noise directionality and non-stationarity in the velocity estimate.Despite the limited number of stations and the short-period char-acter of the seismic sensors,the empirical Green's functions were retrieved for all station pairs using two years of passive data.Both group and phase velocities were derived,the former using the widespread frequency-time analysis,the latter through the analysis of the real part of the cross-spectra.The main advantage of combining these two methods is a more accurate identification of higher modes,resulting in a reduction of ambiguity during picking and data interpretation.Surface wave tomography was run to obtain the spatial distribution of group and phase velocities for the same wavelengths.The low standard deviation of the results suggests that the sparse character of the network does not limit the applicability of the method,for this specific case.The obtained maps highlight the presence of a lower velocity area that extends from the centre of the network towards southeast.Group and phase velocity dispersion curves have been jointly inverted to retrieve as many shear-wave velocity profiles as selected station pairs.While the average model can be used for a more accurate location of the local natural seismicity,the associated standard deviations give us an indication of the lateral heterogeneity of seismic velocities as a function of depth.Finally,the same velocity analysis was repeated for different time windows in order to quantify the error associated to variations in the noise field.Errors as large as 4%have been found,related to the unfavorable orientation of the receiver pairs with respect to strongly directional noise sources,and to the very short time widows.It was shown that using a one-year time window these errors arereduced to 0.3%.
基金support from the Lawrence Livermore National Laboratory(Grant No.B622827)the National Science Foundation(Grant Nos.1824568,1810506,1741707,and 1829071)the Office of Naval Research(Grant No.N00014-16-1-2094).
文摘Laser frequency microcombs provide a series of equidistant,coherent frequency markers across a broad spectrum,enabling advancements in laser spectroscopy,dense optical communications,precision distance metrology,and astronomy.Here,we design and fabricate silicon nitride,dispersion-managed microresonators that effectively suppress avoided-mode crossings and achieve close-to-zero averaged dispersion.Both the stochastic noise and mode-locking dynamics of the resonator are numerically and experimentally investigated.First,we experimentally demonstrate thermally stabilized microcomb formation in the microresonator across different mode-locked states,showing negligible center frequency shifts and a broad frequency bandwidth.Next,we characterize the femtosecond timing jitter of the microcombs,supported by precise metrology of the timing phase and relative intensity noise.For the single-soliton state,we report a relative intensity noise of−153.2 dB∕Hz,close to the shot-noise limit,and a quantum-noise–limited timing jitter power spectral density of 0.4 as 2∕Hz at a 100 kHz offset frequency,measured using a self-heterodyne linear interferometer.In addition,we achieve an integrated timing jitter of 1.7 fs±0.07 fs,measured from 10 kHz to 1 MHz.Measuring and understanding these fundamental noise parameters in high clock rate frequency microcombs is critical for advancing soliton physics and enabling new applications in precision metrology.
基金supported by the National Natural Science Foundation of China(41830103)the Project of Nanjing Center of China Geological Survey(DD20190281).
文摘Dense-array ambient noise tomography is a powerful tool for achieving high-resolution subsurface imag-ing,significantly impacting geohazard prevention and control.Conventional dense-array studies,how-ever,require simultaneous observations of numerous stations for extensive coverage.To conduct a comprehensive karst feature investigation with limited stations,we designed a new synchronous-asyn-chronous observation system that facilitates dense array observations.We conducted two rounds of asynchronous observations,each lasting approximately 24 h,in combination with synchronous backbone stations.We achieved wide-ranging coverage of the study area utilizing 197 nodal receivers,with an average station spacing of 7 m.The beamforming results revealed distinct variations in the noise source distributions between day and night.We estimated the source strength in the stationary phase zone and used a weighting scheme for stacking the cross-correlation functions(C ^(1) functions)to suppress the influ-ence of nonuniform noise source distributions.The weights were derived from the similarity coefficients between multicomponent C^(1)functions related to Rayleigh waves.We employed the cross-correlation of C ^(1) functions(C^(2)methods)to obtain the empirical Green’s functions between asynchronous stations.To eliminate artifacts in C ^(2) functions from higher-mode surface waves in C^(1)functions,we filtered the C^(1)functions on the basis of different particle motions linked to multimode Rayleigh waves.The dispersion measurements of Rayleigh waves obtained from both the C^(1)and C^(2)functions were utilized in surface wave tomography.The inverted three-dimensional(3D)shear-wave(S-wave)velocity model reveals two significant low-velocity zones at depths ranging from 40 to 60 m,which align well with the karst caves found in the drilling data.The method of short-term synchronous-asynchronous ambient noise tomography shows promise as a cost-effective and efficient approach for urban geohazard investigations.
基金supported by the German Federal Ministry of Education and Research,Research Program Quantum Systems(Grant No.13N16774).
文摘Single-wavelength interferometry achieves high resolution for smooth surfaces but struggles with rough industrially relevant ones due to limited unambiguous measuring range and speckle effects.Multiwavelength interferometry addresses these challenges using synthetic wavelengths,enabling a balance between extended measurement range and resolution by combining several synthetic wavelengths.This approach holds immense potential for diverse industrial applications,yet it remains largely untapped due to the lack of suitable light sources.Existing solutions are constrained by limited flexibility in synthetic-wavelength generation and slow switching speeds.We demonstrate a light source for multiwavelength interferometry based on electro-optic single-sideband modulation.It reliably generates synthetic wavelengths with arbitrary values from centimeters to meters and switching time below 30 ms.This breakthrough paves the way for dynamic reconfigurable multiwavelength interferometry capable of adapting to complex surfaces and operating efficiently even outside laboratory settings.These capabilities unlock the full potential of multiwavelength interferometry,offering unprecedented flexibility and speed for industrial and technological applications.
基金supported by the National Natural Science Foundation of China(Grant No.61705193)the Natural Science Foundation of Zhejiang Province(Grant No.LGG20F050002)the Jinhua Science and Technology Plan(Project No.2024-1-064).
文摘Laser interferometry with higher resolution,faster update rate,and larger dynamic range is highly anticipated in the exploration of physics frontiers,advanced manufacturing,and precision sensing.Real-time dispersive spectral interferometry(DSI)shows promise for high-speed precision measurements,whereas the resolution of subnanometers has not yet been achieved.We present a comprehensive theoretical framework to analyze the limitations of real-time DSI based on the signal-to-noise ratio and data volume.A real-time orthogonal polarization spectral interferometry technique is proposed,which utilizes a pair of interferograms with the pi-phase shift to effectively mitigate the phase noise embedded in real-time spectral envelopes,thereby enabling the precise measurements with subnanometer resolution at megahertz frame rates.The recorded time series data are processed through interpolation,segmentation,time–frequency mapping,and de-enveloping to regain the typical cosine-shaped spectral evolution,followed by a fitting-based phase retrieval method to extract the interference phase.The phase resolution of 1.1 mrad(0.91 as for time delay and 0.3 nm for distance)is obtained at the update rate of 22.2 MHz even under the detection bandwidth of 500 MHz,and can be further enhanced to 0.29 mrad(0.24 as for time delay)after 500 times averaging(∼0.5 MHz).Our approach is validated through periodic phase modulations and applied to measure the rapid damped oscillations of a piezo stage,yielding results consistent with those obtained from a commercial picometer interferometer.
基金funded by the Russian Federation Ministry of Science and Higher Education according to the research project FUUW-2025-0033 of the FECIAR UrB RASthe Arkhangelsk branch of the Territorial Fund of Geological Information for the North-Western Federal District for providing geological and geophysical reports for the objects under consideration。
文摘Studying the inner structure of intraplate earthquakes originating in aseismic areas,which are poorly covered by seismic networks or as historical earthquakes is usually the only way to get knowledge about their source mechanisms,which is partially essential for a deeper understanding of intraplate geodynamics.The epicentral zones of earthquakes are situated in hard-toreach areas,so,using active seismic methods for such purposes is unreasonable or even impossible because of high cost and logistical difficulties.We propose a novel approach that combines diverse passive seismic methods,which allows us to get sufficient information about geological environment structure for such task solutions.As an example,we investigated the inner structure of platform earthquake epicentral zone originated up north of Russia.We used four passive seismic methods:microseismic sounding method,passive seismic interferometry,HVSR method,and microseismic activity method.We show that passive seismic data,recoded in the same installation and processed by these different methods,can provide sufficient information about structure of studied environment,needed to explain source mechanism.In sum,the hypocenter zone is presented by intersection of vertical faults and a lateral fractured zone in the middle crust.Results were confirmed by comparison with results by active seismic methods.
基金supported by the National Key Research and Development Program of China(Fund for Young Scientists 2021YFC2900400)Chongqing Outstanding Youth Science Fund project(CSTB2023NSCQ-JQX0027).
文摘Understanding rock behavior is crucial in mine geotechnical engineering to ensure construction efficiency,mitigate rock-related hazards,and promote environmental sustainability.Coda Wave Interferometry(CWI),a non-destructive ultrasonic testing method,has been widely employed to assess micro-damage evolution in rocks induced by perturbations in scatterer position,velocity,or source location due to its exceptional sensitivity.However,challenges persist in evaluating cross-scale rock behavior influenced by nonlinear deformation and multi-field interactions under multiple coupled perturbations.A comprehensive review of the perturbation factors affecting rock damage evolution and potential failure mechanisms is essential for presenting available knowledge in a more systematic and structured manner.This review provides an in-depth analysis of the CWI technique,encompassing its origins,theoretical framework,and classical data processing methodologies.Additionally,it explores the diverse applications of CWI in assessing rock behavior under various perturbation factors,including temperature variations,fluid infiltration,and stress conditions,with a particular emphasis on nonlinear deformation and multi-field coupling effects.Furthermore,a novel method for calculating relative velocity changes in coda waves is introduced,enabling a more precise characterization of the entire rock failure process.The study also proposes a cutting-edge concept of ultra-early and refined monitoring and warning technology for mine rock disasters,leveraging the advancements in CWI.Finally,the review highlights the potential future developments of CWI in high-level intelligent mining scenarios,particularly its integration with ambient noise interferometry and microseismic coda wave analysis.This work serves as a valuable reference,contributing to the refinement of CWI applications for assessing complex rock behavior and enhancing the accuracy of rock disaster prediction and early warning systems.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFC2204601)the National Natural Science Foundation of China(Grant Nos.11925503 and 12275093)+1 种基金the Natural Science Foundation of Hubei Province(Grant No.2021CFB019)the State Key Laboratory of Applied Optics(Grant No.SKLAO2022001A10).
文摘Laser frequency combs,which are composed of a series of equally spaced coherent frequency components,have triggered revolutionary progress in precision spectroscopy and optical metrology.Length/distance is of fundamental importance in both science and technology.We describe a ranging scheme based on chirped pulse interferometry.In contrast to the traditional spectral interferometry,the local oscillator is strongly chirped which is able to meet the measurement pulses at arbitrary distances,and therefore,the dead zones can be removed.The distances can be precisely determined via two measurement steps based on the time-of-flight method and synthetic wavelength interferometry,respectively.To overcome the speed limitation of the optical spectrum analyzer,the spectrograms are stretched and detected by a fast photodetector and oscilloscope and consequently mapped into the time domain in real time.The experimental results indicate that the measurement uncertainty can be well within±2μm,compared with the reference distance meter.The Allan deviation can reach 0.4μm at 4 ns averaging time and 25 nm at 1μs and can achieve 2 nm at 100μs averaging time.We also measured a spinning disk with grooves of different depths to verify the measurement speed,and the results show that the grooves with about 150 m∕s line speed can be clearly captured.Our method provides a unique combination of non-dead zones,ultrafast measurement speed,high precision and accuracy,large ambiguity range,and only one single comb source.This system could offer a powerful solution for field measurements in practical applications in the future.
基金supported by the CNPC-SWPU Innovation Alliance Technology Cooperation Project(2020CX020000)the National Natural Science Foundation of China(42022028)+1 种基金the Natural Science Foundation of Sichuan Province(24NSFSC0808)the China Scholarship Council(202306440144)。
文摘In common practice in the oil fields,the injection of water and gas into reservoirs is a crucial technique to increase production.The control of the waterflooding front in oil/gas exploitation is a matter of great concern to reservoir engineers.Monitoring the waterflooding front in oil/gas wells plays a very important role in adjusting the well network and later in production,taking advantage of the remaining oil po-tential and ultimately achieving great success in improving the recovery rate.For a long time,micro-seismic monitoring,numerical simulation,four-dimensional seismic and other methods have been widely used in waterflooding front monitoring.However,reconciling their reliability and cost poses a significant challenge.In order to achieve real-time,reliable and cost-effective monitoring,we propose an innovative method for waterflooding front monitoring through the similarity analysis of passive source time-lapse seismic images.Typically,passive source seismic data collected from oil fields have extremely low signal-to-noise ratio(SNR),which poses a serious problem for obtaining structural images.The proposed method aims to visualize and analyze underground changes by highlighting time-lapse images and provide a strategy for underground monitoring using long-term passive source data under low SNR conditions.First,we verify the feasibility of the proposed method by designing a theoretical model.Then,we conduct an analysis of the correlation coefficient(similarity)on the passive source time-lapse seismic imaging results to enhance the image differences and identify the simulated waterflooding fronts.Finally,the proposed method is applied to the actual waterflooding front monitoring tasks in Shengli Oilfield,China.The research findings indicate that the monitoring results are consistent with the actual devel-opment conditions,which in turn demonstrates that the proposed method has great potential for practical application and is very suitable for monitoring common development tasks in oil fields.
基金supported by the National Natural Science Foundation of China(No.42374177)。
文摘Passive surface wave imaging has been a powerful tool for near-surface characterization in urban areas,which extracts surface wave signals from ambient seismic noise and then estimates subsurface shear wave velocity by inversion of the measured phase velocity.The high-frequency(approximately>1 Hz)seismic noise fields in urban environments are dominantly induced by human activities such as the vehicle traffic.Traffic seismic sources are nonrandomly distributed in time and space.Applying standard interferometric techniques to recordings from these nonrandom noise sources makes the Green’s function liable to estimation errors.We analyze the influence of using nonrandom traffic seismic sources for surface wave imaging.With nonrandom traffic seismic sources in time,spurious signals are generated in the cross-correlation function.With nonrandom traffic seismic sources in space,surface-wave phase velocities could be overestimated in the dispersion measurement.We provide an overview of solutions for surface-wave imaging with nonrandom traffic seismic sources in time and space,aiming to improve the retrieval of high-frequency surface waves and achieve reliable results from ultrashort(tens of seconds)observations for near-surface characterization.
基金supported by the National Natural Science Foundation of China (Grant No. 12005106)support from the National Natural Science Foundation of China (Grant No. 11974189)+1 种基金support from the National Natural Science Foundation of China (Grant No. 12175106)the Postgraduate Research and Practice Innovation Program of Jiangsu Province (Grant No. JSCX23-0260)。
文摘We propose a quantum-enhanced metrological scheme utilizing unbalanced entangled coherent states(ECSs) generated by passing a coherent state and a coherent state superposition through an unbalanced beam splitter(BS). We identify the optimal phase sensitivity of this scheme by maximizing the quantum Fisher information(QFI) with respect to the BS transmission ratio. Our scheme outperforms the conventional scheme with a balanced BS, particularly in the presence of single-mode photon loss. Notably, our scheme retains quantum advantage in phase sensitivity in the limit of high photon intensity, where the balanced scheme offers no advantage over the classical strategy.
基金supported by the Anhui Zhongchuang Energy New Energy Technology Co.,Ltd.,Entrusted Project.
文摘The semiconductor bridge(SCB)ignites through bridge film discharge,offering advantages such as low ignition energy,high safety,and compatibility with digital logic circuits.The study uses laser interferometry to investigate the gas dynamics of the bridge film after SCB plasma extinction.Interferometric images of the SCB film gas were obtained through a laser interferometry optical path.After the degradation model of digital image processing,clearer images were produced to facilitate analysis and calculation.The results show that the gas temperature at the center of the SCB film reaches a maximum of 1000 K,and the temperature rapidly decreases along the axial direction of the bridge surface to room temperature at 300 K.The maximum diffusion velocity of the plasma is 1.8 km/s.These findings provide critical insights for SCB design and ignition control.
基金funded by Natural Science Foundation of Shanghai,China(No.23ZR1426100)SAAS program for Excellent Research Team(No.G202203)。
文摘The taste presentation and receptor perception mechanism of the salty peptide of Stropharia rugosoannulata were predicted and verified using peptide omics and molecular interaction techniques.The combination of aspartic acid(D)and glutamic acid(E),or peptide fragments composed of arginine(R),constitute the characteristic taste structural basis of salty peptides of S.rugosoannulata.The taste intensity of the salty peptide positively correlates with its concentration within a specific concentration range(0.25–1.0 mg/mL).The receptor more easily recognizes the first amino acid residue at the N-terminal of salty peptides and the aspartic acid residue in the peptides.GLU513,ASP707,and VAL508 are the critical amino acid residues for the receptor to recognize salty peptides.TRPV1 is specifically the receptor for recognizing salty peptides.Hydrogen bonds and electrostatic interactions are the main driving forces for the interactions between salty peptides and TRPV1 receptors.KSWDDFFTR has the most potent binding capacity with the receptor and has tremendous potential for application in sodium salt substitution.This study confirmed the taste receptor that specifically recognizes salty peptides,analyzed the receptor-peptide binding interaction,and provided a new idea for understanding the taste receptor perception of salty peptides.
基金supported by the National Natural Science Foundation of China(Grant No.62275188)the Central Guidance on Local Science and Technology Development Fund(Grant No.YDZJSX2024D019)+1 种基金the International Scientific and Technological Cooperative Project in Shanxi Province(Grant No.202104041101009)the Natural Science Foundation of Shanxi Province of China through Research Project(Grant No.20210302123195).
文摘We propose pattern self-referenced single-pixel common-path holography(PSSCH),which can be realized using either the digital-micromirror-device(DMD)based off-axis scheme or the DMD-based phaseshifting approach,sharing the same experimental setup,to do wavefront reconstructions.In this method,each modulation pattern is elaborately encoded to be utilized to not only sample the target wavefront but also to dynamically introduce the reference light for single-pixel common-path holographic detection.As such,it does not need to intentionally introduce a static reference light,resulting in it making full use of the pixel resolution of the modulation patterns and suppressing dynamically varying noises.Experimental demonstrations show that the proposed method can not only obtain a larger field of view than the peripheral-referenced approach but also achieve a higher imaging resolution than the checkerboardreferenced approach.The phase-shifting-based PSSCH performs better than the off-axis-based PSSCH on imaging fidelity,while the imaging speed of the latter is several times faster.Further,we demonstrate our method to do wavefront imaging of a biological sample as well as to do phase detection of a physical lens.The experimental results suggest its effectiveness in applications.
基金support of the following research Projects (Nos.GZ:LE 992/14-3 and LE 992/18-1)by the Deutsche Forschungsgemeinschaft and the EMPIR program (project TracOptic,20IND07)co-financed by the European Union’s Horizon 2020 Research and Innovation Program.
文摘We present a unified electromagnetic modeling of coherence scanning interferometry,confocal microscopy,and focus variation microscopy as the most common techniques for surface topography inspection with micro-and nanometer resolution.The model aims at analyzing the instrument response and predicting systematic deviations.Since the main focus lies on the modeling of the microscopes,the light–surface interaction is considered,based on the Kirchhoff approximation extended to vectorial imaging theory.However,it can be replaced by rigorous methods without changing the microscope model.We demonstrate that all of the measuring instruments mentioned above can be modeled using the same theory with some adaption to the respective instrument.For validation,simulated results are confirmed by comparison with measurement results.
