Residual stress induced during manufacturing of injection molded components such as polymethyl methacrylate （PMMA） affects the mechanical and optical properties of these components. These residual stresses can be vi...Residual stress induced during manufacturing of injection molded components such as polymethyl methacrylate （PMMA） affects the mechanical and optical properties of these components. These residual stresses can be visualized and quantified by measuring their birefringence. In this paper, a low birefringence polariscope （LBP） is used to measure the whole-field residual stress distribution of these injection molded specimens. Detailed analytical and experimental study is conducted to quantify the residual stress measurement in these materials. A commercial birefringence measurement system was used to validate the results obtained to our measurement system. This study can help in material diagnosis for quality and manufacturing purpose and be useful for understanding of residual stress in imaging or other anolications.展开更多
Digital Holography (DH) has brought a new impetus to the field of holography. The fields of imaging, microscopy and metrology have all benefited from these developments. In this paper some of these developments will b...Digital Holography (DH) has brought a new impetus to the field of holography. The fields of imaging, microscopy and metrology have all benefited from these developments. In this paper some of these developments will be described with some applications in the fields of color imaging, amplitude and phase microscopy and dynamic metrology. It is envisaged that this field will rapidly advance in the next couple of years and become an expected imaging and measurement modality especially in the field of micro, nano and bio sciences.展开更多
his paper adopts the 3-3-2 information processing method for the capture of moving objects as its premise, and proposes a basic principle of three-dimensional (3D) imaging using biological compound eye. Traditional bi...his paper adopts the 3-3-2 information processing method for the capture of moving objects as its premise, and proposes a basic principle of three-dimensional (3D) imaging using biological compound eye. Traditional bionic vision is limited by the available hardware. Therefore, in this paper, the new-generation technology of microlens-array light-field camera is proposed as a potential method for the extraction of depth information from a single image. A significant characteristic of light-field imaging is that it records intensity and directional information from the lights entering the camera. Herein, a refocusing method using light-field image is proposed. By calculating the focusing cost at different depths from the object, the imaging plane of the object is determined, and a depth map is constructed based on the position of the object’s imaging plane. Compared with traditional light-field depth estimation, the depth map calculated by this method can significantly improve resolution and does not depend on the number of light-field microlenses. In addition, considering that software algorithms rely on hardware structure, this study develops an imaging hardware that is only 7 cm long based on the second-generation microlens camera’s structure, further validating its important refocusing characteristics. It thereby provides a technical foundation for 3D imaging with a single camera.展开更多
In this paper a Fiber Bragg Grating (FBG) Strain Rosette is designed, developed and tested. Traditional FBGs measure strain in only one direction. However, in-plane strain at a point consists of two normal strains and...In this paper a Fiber Bragg Grating (FBG) Strain Rosette is designed, developed and tested. Traditional FBGs measure strain in only one direction. However, in-plane strain at a point consists of two normal strains and one shear strain. Hence a FBG strain rosette needs to be designed. The sensing principle of FBGs as a strain and temperature sensor and fundamental principles of strain transformation and strain gage rosettes are discussed.FBG strain rosettes are fabricated and embedded in two materials namely, Silicon Gel RTV 146-9 and Glass Fiber Composite Laminates. Experiments were conducted on the FBG strain rosette structures that were embedded in Silicon Gel (RTV 146-9). Initial findings from the experiments as well as preferred embedding material are presented.展开更多
Recently, optical techniques have attracted great attention due to their excellent non-destructive, non-contact, high-resolution, and full-field characteristics. Applications can be found in diverse fields such as pre...Recently, optical techniques have attracted great attention due to their excellent non-destructive, non-contact, high-resolution, and full-field characteristics. Applications can be found in diverse fields such as precision mechanics and manufacturing, aerospace and automotive testing and inspection, materials science, and biomedical engineering. Advances in Optical Techniques for Me- chanical Measurements presents the latest research progresses in several widely used optical techniques with applications in preci- sion mechanical engineering.展开更多
In-line digital holography helps to relax the spatial resolution requirement on charge-coupled device sensors for digital recording of holograms and to utilize the full sensing area for image reconstruction which prov...In-line digital holography helps to relax the spatial resolution requirement on charge-coupled device sensors for digital recording of holograms and to utilize the full sensing area for image reconstruction which provides larger field of view and better imaging resolution. In this letter, a lensless in-line digital holographic microscopy is presented for dynamic metrology of micro-electro-mechanical system devices. The methodologies of interferometry and time-averaged in-line digital holography are presented for dynamic measurements, which are also useful for simultaneous suppression of in-line waves from real image wave. The experimental results are presented for dynamic thermal characterization of microheater and vibration analysis of cantilevers.展开更多
Infrared thermography determines the surface temperature of an object or human body. It is a promising imaging technology for medical and biological observations due to its contactless and completely non- invasive pro...Infrared thermography determines the surface temperature of an object or human body. It is a promising imaging technology for medical and biological observations due to its contactless and completely non- invasive properties. However, traditional two-dimensional （2D） infrared thermography cannot retain the spatial information, and thus provides only qualitative diagnosis information. A novel real-time three- dimensional （3D） infrared imaging system which takes full advantages of high-speed, high-quality, high- sensitivity, and low-cost in 3D thermograph is presented. We demonstrate the real-time 3D thermal imaging at the speed of 24 frmnes per second （fps）, with resolution of 640 ×480 points. Experimental results demonstrate quantitatively measurement of temperature distribution of 3D surfaces in real-time is realized with this system.展开更多
This article focuses on health monitoring of structures using multiple smart materials.In this research,two fiber-optic sensors,namely fiber Bragg grating(FBG)and fiber-optic polarimetric sensor(FOPS),are investigated...This article focuses on health monitoring of structures using multiple smart materials.In this research,two fiber-optic sensors,namely fiber Bragg grating(FBG)and fiber-optic polarimetric sensor(FOPS),are investigated for damage detection in the beam specimen.FBG is used for local strain measurement while FOPS is used for global strain measurement.Both FBG and FOPS show significant changes in the strain due to damages in the specimen.Also,at the center of the specimen,piezoelectric wafer active sensor(PWAS)is attached.The electromechanical admittance(EMA)signature of the specimen beam is recorded by PWAS.The changes in the amplitudes of the peaks obtained at various frequencies in this EMA signature are analyzed,and it is shown that the peak amplitudes respond differently to damages and to change in loading.Thus,multiple smart materials(FBG,FOPS,and PWAS)are used to get improved information on the health of the beam.展开更多
文摘Residual stress induced during manufacturing of injection molded components such as polymethyl methacrylate （PMMA） affects the mechanical and optical properties of these components. These residual stresses can be visualized and quantified by measuring their birefringence. In this paper, a low birefringence polariscope （LBP） is used to measure the whole-field residual stress distribution of these injection molded specimens. Detailed analytical and experimental study is conducted to quantify the residual stress measurement in these materials. A commercial birefringence measurement system was used to validate the results obtained to our measurement system. This study can help in material diagnosis for quality and manufacturing purpose and be useful for understanding of residual stress in imaging or other anolications.
文摘Digital Holography (DH) has brought a new impetus to the field of holography. The fields of imaging, microscopy and metrology have all benefited from these developments. In this paper some of these developments will be described with some applications in the fields of color imaging, amplitude and phase microscopy and dynamic metrology. It is envisaged that this field will rapidly advance in the next couple of years and become an expected imaging and measurement modality especially in the field of micro, nano and bio sciences.
基金The National Major Project Research and Development Project (2017YFB0503003)The National Natural Science Foundation of China(61101157, 60602042).
文摘his paper adopts the 3-3-2 information processing method for the capture of moving objects as its premise, and proposes a basic principle of three-dimensional (3D) imaging using biological compound eye. Traditional bionic vision is limited by the available hardware. Therefore, in this paper, the new-generation technology of microlens-array light-field camera is proposed as a potential method for the extraction of depth information from a single image. A significant characteristic of light-field imaging is that it records intensity and directional information from the lights entering the camera. Herein, a refocusing method using light-field image is proposed. By calculating the focusing cost at different depths from the object, the imaging plane of the object is determined, and a depth map is constructed based on the position of the object’s imaging plane. Compared with traditional light-field depth estimation, the depth map calculated by this method can significantly improve resolution and does not depend on the number of light-field microlenses. In addition, considering that software algorithms rely on hardware structure, this study develops an imaging hardware that is only 7 cm long based on the second-generation microlens camera’s structure, further validating its important refocusing characteristics. It thereby provides a technical foundation for 3D imaging with a single camera.
文摘In this paper a Fiber Bragg Grating (FBG) Strain Rosette is designed, developed and tested. Traditional FBGs measure strain in only one direction. However, in-plane strain at a point consists of two normal strains and one shear strain. Hence a FBG strain rosette needs to be designed. The sensing principle of FBGs as a strain and temperature sensor and fundamental principles of strain transformation and strain gage rosettes are discussed.FBG strain rosettes are fabricated and embedded in two materials namely, Silicon Gel RTV 146-9 and Glass Fiber Composite Laminates. Experiments were conducted on the FBG strain rosette structures that were embedded in Silicon Gel (RTV 146-9). Initial findings from the experiments as well as preferred embedding material are presented.
文摘Recently, optical techniques have attracted great attention due to their excellent non-destructive, non-contact, high-resolution, and full-field characteristics. Applications can be found in diverse fields such as precision mechanics and manufacturing, aerospace and automotive testing and inspection, materials science, and biomedical engineering. Advances in Optical Techniques for Me- chanical Measurements presents the latest research progresses in several widely used optical techniques with applications in preci- sion mechanical engineering.
基金supported by the National Research Foundation of Singapore under Proof of Con-cept (POC) scheme (No 2008 NRF-POC0001-068)
文摘In-line digital holography helps to relax the spatial resolution requirement on charge-coupled device sensors for digital recording of holograms and to utilize the full sensing area for image reconstruction which provides larger field of view and better imaging resolution. In this letter, a lensless in-line digital holographic microscopy is presented for dynamic metrology of micro-electro-mechanical system devices. The methodologies of interferometry and time-averaged in-line digital holography are presented for dynamic measurements, which are also useful for simultaneous suppression of in-line waves from real image wave. The experimental results are presented for dynamic thermal characterization of microheater and vibration analysis of cantilevers.
基金This work was supported by the Research Fund for the Doctoral Program of Ministry of Education of China （No. 20123219110016） and the National Natural Science Foundation of China （No. 61271332）, and the Research and Innovation Plan for Graduate Students of Jiangsu Higher Education Institutions, China （No. CXZZ11_0237）. Chao Zuo gratefully acknowledges the financial support from China Scholarship Council （No. 201206840009）.
文摘Infrared thermography determines the surface temperature of an object or human body. It is a promising imaging technology for medical and biological observations due to its contactless and completely non- invasive properties. However, traditional two-dimensional （2D） infrared thermography cannot retain the spatial information, and thus provides only qualitative diagnosis information. A novel real-time three- dimensional （3D） infrared imaging system which takes full advantages of high-speed, high-quality, high- sensitivity, and low-cost in 3D thermograph is presented. We demonstrate the real-time 3D thermal imaging at the speed of 24 frmnes per second （fps）, with resolution of 640 ×480 points. Experimental results demonstrate quantitatively measurement of temperature distribution of 3D surfaces in real-time is realized with this system.
基金The authors acknowledge the financial support from NTU,Singapore.
文摘This article focuses on health monitoring of structures using multiple smart materials.In this research,two fiber-optic sensors,namely fiber Bragg grating(FBG)and fiber-optic polarimetric sensor(FOPS),are investigated for damage detection in the beam specimen.FBG is used for local strain measurement while FOPS is used for global strain measurement.Both FBG and FOPS show significant changes in the strain due to damages in the specimen.Also,at the center of the specimen,piezoelectric wafer active sensor(PWAS)is attached.The electromechanical admittance(EMA)signature of the specimen beam is recorded by PWAS.The changes in the amplitudes of the peaks obtained at various frequencies in this EMA signature are analyzed,and it is shown that the peak amplitudes respond differently to damages and to change in loading.Thus,multiple smart materials(FBG,FOPS,and PWAS)are used to get improved information on the health of the beam.
