Crossed grating stuck to metal surface was used as a strain sensor in the present work, and stress as well as strain were then investigated by accurately determining the change in the position of diffraction spot befo...Crossed grating stuck to metal surface was used as a strain sensor in the present work, and stress as well as strain were then investigated by accurately determining the change in the position of diffraction spot before and after deformed. A hardware testing system for linear CCD array, data gathering and processing was therefore developed for this purpose. Experimental results showed that the system has a good accuracy and can be used to measure stress and strain of metal surface in a real-time and quantitative manner.展开更多
Spatial filtering velocimetry(SFV)has the advantages of simple structure,good stability,and wide applications.However,the traditional linear CCD-based SFV method requires an accurate angle between the direction of lin...Spatial filtering velocimetry(SFV)has the advantages of simple structure,good stability,and wide applications.However,the traditional linear CCD-based SFV method requires an accurate angle between the direction of linear CCD and the direction of moving object,so it is not suitable for measuring a complex flow field or two-dimensional speed in a granular media.In this paper,a new extension of spatial filtering method(SFM)based on high speed array CCD camera is proposed as simple and effective technique for measuring two-dimensional speed field of granular media.In particular,we analyzed the resolution and range of array CCD-based SFV so that the reader can clarify the application scene of this method.This method has a particular advantage for using orthogonal measurement to avoid the angle measurement,which were problematic when using linear CCD to measure the movement.Finally,the end-wall effects of the granular flow in rotating drum is studied with different experimental conditions by using this improved technique.展开更多
A real-time auto-focusing system with auto-collimation method is introduced, which is used in auto-detecting the focus of the space camera with long focus. Auto-focusing is the key technique to ensure high quality in ...A real-time auto-focusing system with auto-collimation method is introduced, which is used in auto-detecting the focus of the space camera with long focus. Auto-focusing is the key technique to ensure high quality in space imaging. It can measure and compensate the defocus caused by the change of temperature and air pressure etc. in space. To solve the problem of auto-focusing with auto-collimation method of the camera whose axis is perpendicular to the ground, it is designed that two small caliber pentagonal prisms are placed in the area of aperture suitable to the camera’s relative aperture based on the theory of auto-focusing with auto-collimation, which can replace the big caliber plane reflector used in other cameras. Using the characteristic of pentagonal prism refracting light vertically, the target slit is imaged in CCD through the two-separated lens. It transforms the detecting of the axial defocusing quantity to the landscape orientation measurement of the faculae’s position in the direction of CCD pixels. The defocusing quantity is obtained by measuring the opposite position of the two faculae on the CCD. The Centroid method is adopted to measure the position of the auto-collimation faculae. The arithmetic error is analyzed especially, and the causation is given. Experiments show that this real-time auto-focusing system using centroid method is reliable and the focusing precision can reach ±0.01 mm.展开更多
文摘Crossed grating stuck to metal surface was used as a strain sensor in the present work, and stress as well as strain were then investigated by accurately determining the change in the position of diffraction spot before and after deformed. A hardware testing system for linear CCD array, data gathering and processing was therefore developed for this purpose. Experimental results showed that the system has a good accuracy and can be used to measure stress and strain of metal surface in a real-time and quantitative manner.
基金Project supported by the National Natural Science Foundation of China(Grant No.11902190)the Construction Project of Shanghai Key Laboratory of Molecular Imaging(Grant No.18DZ2260400)the Fund from the Shanghai Municipal Education Commission,China(Class II Plateau Disciplinary Construction Program of Medical Technology of SUMHS,2018-2020).
文摘Spatial filtering velocimetry(SFV)has the advantages of simple structure,good stability,and wide applications.However,the traditional linear CCD-based SFV method requires an accurate angle between the direction of linear CCD and the direction of moving object,so it is not suitable for measuring a complex flow field or two-dimensional speed in a granular media.In this paper,a new extension of spatial filtering method(SFM)based on high speed array CCD camera is proposed as simple and effective technique for measuring two-dimensional speed field of granular media.In particular,we analyzed the resolution and range of array CCD-based SFV so that the reader can clarify the application scene of this method.This method has a particular advantage for using orthogonal measurement to avoid the angle measurement,which were problematic when using linear CCD to measure the movement.Finally,the end-wall effects of the granular flow in rotating drum is studied with different experimental conditions by using this improved technique.
文摘A real-time auto-focusing system with auto-collimation method is introduced, which is used in auto-detecting the focus of the space camera with long focus. Auto-focusing is the key technique to ensure high quality in space imaging. It can measure and compensate the defocus caused by the change of temperature and air pressure etc. in space. To solve the problem of auto-focusing with auto-collimation method of the camera whose axis is perpendicular to the ground, it is designed that two small caliber pentagonal prisms are placed in the area of aperture suitable to the camera’s relative aperture based on the theory of auto-focusing with auto-collimation, which can replace the big caliber plane reflector used in other cameras. Using the characteristic of pentagonal prism refracting light vertically, the target slit is imaged in CCD through the two-separated lens. It transforms the detecting of the axial defocusing quantity to the landscape orientation measurement of the faculae’s position in the direction of CCD pixels. The defocusing quantity is obtained by measuring the opposite position of the two faculae on the CCD. The Centroid method is adopted to measure the position of the auto-collimation faculae. The arithmetic error is analyzed especially, and the causation is given. Experiments show that this real-time auto-focusing system using centroid method is reliable and the focusing precision can reach ±0.01 mm.
