The “Monitoring City Walls” research project by the University of Pisa approaches planned conservation as a process that pursues an in-depth understanding of historic city walls and their surroundings to define a sy...The “Monitoring City Walls” research project by the University of Pisa approaches planned conservation as a process that pursues an in-depth understanding of historic city walls and their surroundings to define a system of effective risk prevention. This multidisciplinary research adopts monitoring strategies and technologies at the large scale and in relationship to natural and urban conditions. The underlying logic frames the conservation of these historic fortifications within the more general mitigation of risks generated by context. The research aims to develop an innovative approach to monitoring ancient defensive structures in historical towns. The integrated use of advanced technologies allows for the control and, most importantly, advance identification of possible risks. These new technologies, in particular satellite interferometry, make it possible to improve and increase the operational capacity of monitoring processes by facilitating the acquisition and investigation of data relative to the system defined by ancient city walls and their surroundings. These technologies also represent a cost-effective tool for managing the important transition from the observation and study of individual monuments to the monitoring of large monumental complexes or even entire historical centers.展开更多
The paper presents a number of signal processing approaches for the spectral interferometric interrogation of extrinsic Fabry-Perot interferometers(EFPIs). The analysis of attainable microdisplacement resolution is pe...The paper presents a number of signal processing approaches for the spectral interferometric interrogation of extrinsic Fabry-Perot interferometers(EFPIs). The analysis of attainable microdisplacement resolution is performed and the analytical equations describing the dependence of resolution on parameters of the interrogation setup are derived. The efficiency of the proposed signal processing approaches and the validity of analytical derivations are supported by experiments. The proposed approaches allow the interrogation of up to four multiplexed sensors with attained resolution between 30 pm and 80 pm, up to three times improvement of microdisplacement resolution of a single sensor by means of using the reference interferometer and noisecompensating approach, and ability to register signals with frequencies up to 1 kHz in the case of 1 Hz spectrum acquisition rate. The proposed approaches can be used for various applications, including biomedical, industrial inspection, and others, amongst the microdisplacement measurement.展开更多
Three dimensional（3D） displacements, which can be translated further into 3D strain, are key parameters tor design, manufacturing and quality control. Using different optical setups, phase-shift methods, and algorit...Three dimensional（3D） displacements, which can be translated further into 3D strain, are key parameters tor design, manufacturing and quality control. Using different optical setups, phase-shift methods, and algorithms, several different 3D electronic speckle pattern interferometry（ESPl） systems for displacement and strain measurements have been achieved and commercialized. This paper provides a review of the recent developments in ESPI systems for 3D displacement and strain measurement. After an overview of the fundamentals of ESP! theory, temporal phase-shift, and spatial phase-shift techniques, 3D deformation measurements by the temporal phase-shift ESPI system, which is suited well for static measurement, and by the spatial phase-shift ESPI system, which is particularly useful for dynamic measurement, are discussed. For each method, the basic theory, a brief derivation and different optical layouts are presented. The state of art application, potential and limitation of the ESPI systems are shown and demonstrated.展开更多
Laser Ultrasonic Testing(LUT)holds great promise for industrial applications,particularly in Nondestructive Testing(NDT)of aerospace composites.It offers advantages such as non-contact,high-resolution,and real-time de...Laser Ultrasonic Testing(LUT)holds great promise for industrial applications,particularly in Nondestructive Testing(NDT)of aerospace composites.It offers advantages such as non-contact,high-resolution,and real-time defect detection.Traditional NDT methods struggle with the complex shapes of structural parts and in-situ testing,limiting their detection efficiency and sensitivity.We review the principles of excitation,optical detection,and laser parameter selection for LUT.It also compares applicability of LUT with other NDT techniques.We discuss strengths and limitations of LUT in detecting defects,characterizing material properties,and monitoring the health of aerospace composites.LUT has proven effective in detecting defects in aerospace materials under extreme conditions such as high temperature and pressure during manufacturing and service.However,challenges remain in defect localization,rapid identification,signal extraction in noisy environments,and micro-defect characterization.Despite these limitations,LUT stands out for its non-contact real-time capabilities and its ability to detect defects in harsh industrial conditions.This paper enhances the understanding for potential and future development of LUT,including improvements in laser generators,non-contact inspection equipment,modular inspection device design,and high-accuracy real-time inspection technologies.展开更多
基金Thanks to Jacinto E.Canivell Garcia De Paredes,Emilio Jose Mascort Albea and Rocio Romero Hernandez at the University of Seville for the support provided in defining the digital mapping instruments.
文摘The “Monitoring City Walls” research project by the University of Pisa approaches planned conservation as a process that pursues an in-depth understanding of historic city walls and their surroundings to define a system of effective risk prevention. This multidisciplinary research adopts monitoring strategies and technologies at the large scale and in relationship to natural and urban conditions. The underlying logic frames the conservation of these historic fortifications within the more general mitigation of risks generated by context. The research aims to develop an innovative approach to monitoring ancient defensive structures in historical towns. The integrated use of advanced technologies allows for the control and, most importantly, advance identification of possible risks. These new technologies, in particular satellite interferometry, make it possible to improve and increase the operational capacity of monitoring processes by facilitating the acquisition and investigation of data relative to the system defined by ancient city walls and their surroundings. These technologies also represent a cost-effective tool for managing the important transition from the observation and study of individual monuments to the monitoring of large monumental complexes or even entire historical centers.
文摘The paper presents a number of signal processing approaches for the spectral interferometric interrogation of extrinsic Fabry-Perot interferometers(EFPIs). The analysis of attainable microdisplacement resolution is performed and the analytical equations describing the dependence of resolution on parameters of the interrogation setup are derived. The efficiency of the proposed signal processing approaches and the validity of analytical derivations are supported by experiments. The proposed approaches allow the interrogation of up to four multiplexed sensors with attained resolution between 30 pm and 80 pm, up to three times improvement of microdisplacement resolution of a single sensor by means of using the reference interferometer and noisecompensating approach, and ability to register signals with frequencies up to 1 kHz in the case of 1 Hz spectrum acquisition rate. The proposed approaches can be used for various applications, including biomedical, industrial inspection, and others, amongst the microdisplacement measurement.
基金supported by National Natural Science Foundation of China(Grant Nos.51275054,51075116)
文摘Three dimensional（3D） displacements, which can be translated further into 3D strain, are key parameters tor design, manufacturing and quality control. Using different optical setups, phase-shift methods, and algorithms, several different 3D electronic speckle pattern interferometry（ESPl） systems for displacement and strain measurements have been achieved and commercialized. This paper provides a review of the recent developments in ESPI systems for 3D displacement and strain measurement. After an overview of the fundamentals of ESP! theory, temporal phase-shift, and spatial phase-shift techniques, 3D deformation measurements by the temporal phase-shift ESPI system, which is suited well for static measurement, and by the spatial phase-shift ESPI system, which is particularly useful for dynamic measurement, are discussed. For each method, the basic theory, a brief derivation and different optical layouts are presented. The state of art application, potential and limitation of the ESPI systems are shown and demonstrated.
基金co-supported by the Natural Science Foundation of China(NSFC)(Nos.52305139 and 52175124)Zhejiang Provincial Natural Science Foundation,China(Nos.LQ23E050017 and LZ21E050003)+1 种基金the Fundamental Research Funds for the Provincial Universities of Zhejiang,China(No.RF-A2024001)the China Postdoctoral Science Foundation(No.2025M771342)。
文摘Laser Ultrasonic Testing(LUT)holds great promise for industrial applications,particularly in Nondestructive Testing(NDT)of aerospace composites.It offers advantages such as non-contact,high-resolution,and real-time defect detection.Traditional NDT methods struggle with the complex shapes of structural parts and in-situ testing,limiting their detection efficiency and sensitivity.We review the principles of excitation,optical detection,and laser parameter selection for LUT.It also compares applicability of LUT with other NDT techniques.We discuss strengths and limitations of LUT in detecting defects,characterizing material properties,and monitoring the health of aerospace composites.LUT has proven effective in detecting defects in aerospace materials under extreme conditions such as high temperature and pressure during manufacturing and service.However,challenges remain in defect localization,rapid identification,signal extraction in noisy environments,and micro-defect characterization.Despite these limitations,LUT stands out for its non-contact real-time capabilities and its ability to detect defects in harsh industrial conditions.This paper enhances the understanding for potential and future development of LUT,including improvements in laser generators,non-contact inspection equipment,modular inspection device design,and high-accuracy real-time inspection technologies.
