In a conventional moire method, achieving both measurement accuracy and dynamic measurement and balancing field of view and measurement accuracy have been difficult. The present invention makes it possible to handle conventional moire fringes as a grating for generating phase-shifted second-order moire fringes, use a spatial phase shift method algorithm to accurately analyze the phases of the second-order moire fringes before and after deformation, and determine shape from the phase differences between gratings projected onto the surface of an object of measurement and a reference surface and determine deformation and strain from the phase differences between the second-order moire fringes, before and after deformation, of a repeating pattern on the object surface or a produced grating. As a result, it is possible to measure the three-dimensional shape and deformation distribution of an object accurately and with a wide field of view or dynamically and with a high degree of accuracy.

Three-dimensional shape, displacement, and strain measurement device and method using periodic pattern, and program therefor

The invention discloses an X-ray grating differential phase contrast imaging method and device based on a two-dimensional dislocation absorption grating. The method comprises the following steps: arranging a Talbot-Lau imaging structure according to a novel two-dimensional dislocation absorption grating provided in the invention; acquiring a two-dimensional intensity image of X rays passing through an object by virtue of the previous structure; and separating three images from the acquired two-dimensional intensity image by a Fourier analysis method, namely an X-ray absorption contrast image,a differential phase contrast image and a scattering contrast image. Compared with the traditional method, the method in the embodiment of the invention has the advantages that the grating does not need to be moved, the three contrast images can be acquired by virtue of single exposure, the imaging time is greatly shortened, the imaging dose is reduced, and the imaging efficiency and stability ofthe system are improved.

X-ray grating differential phase contrast imaging method and device based on two-dimensional dislocation absorption grating

The invention discloses a displacement measurement method combining a digital image correlation technology and a moire sampling method. The digital image correlation method is used for assisting the moire sampling method to perform displacement measurement. The method comprises the following steps of (1) acquiring a mark point displacement sequence image with a grating pattern through a camera; (2) computing mark point displacement and a phase change value frame by frame by adopting the digital image correlation method; (3) computing moire fringe phase by adopting the moire sampling method; and (4) computing a grating mark displacement value in the sequence image. The method has the following beneficial effects of being high in displacement measurement precision, large in measuring range,simple and convenient to calculate, wide in applicability, free of camera calibration and the like.

Displacement measurement method combining digital image correlation technology and moire sampling method

The invention provides a method for monitoring a tower crane by utilizing high-speed photogrammetric technology. The method comprises the following steps: acquiring images in a cargo beam movement process of a standard crane tower by using a high-speed camera so as to form a monitoring image; computing a relationship between the cargo beam movement speed and an image matrix change coefficient in the adjacent image interval, and establishing a mathematical model; acquiring the cargo beam movement speed and the theoretical image matrix change coefficient in the interval between the first image and the second image in the carbo beam movement process of the current crane tower; computing the actual image matrix change coefficients of the current two images; and giving an alarm to a user side when the difference between the theoretical image matrix change coefficient and the actual image matrix change coefficient is greater than a predetermined threshold. The cargo beam movement image is shot through the high-speed photogrammetric technology, and the image parameters are modelled and monitored, thereby monitoring the state of the crane tower when the cargo beam moves, and improving thesecurity of the crane tower.

Method for monitoring tower crane by utilizing high-speed photogrammetric technology

PROBLEM TO BE SOLVED: To solve a problem that, though a scan moire method and a sampling moire method have many advantages in a displacement strain distribution measurement in a static state, it takes a time to obtain a high resolution image when a scanning type laser microscope is used in the case of performing a dynamic displacement strain distribution measurement, and alternately, in the measurement of plane deformation, it is necessary to rotate a sample stage or a main scan line of a microscope by 90°, and there is a problem that during that time the sample is affected by deformation, and hence, a secondary deformation strain distribution of a structural material cannot be measured promptly and correctly.SOLUTION: The number of scan lines is reduced, and a moire image is acquired at a higher speed without lowering a measurement sensitivity of displacement and strain. Scan point intervals in two directions of x and y are appropriately arranged by using a crossed grating for a sample grating and separated into primary scan moire fringes from one moire fringe image acquired without rotating the sample, and a secondary displacement strain distribution of the structural material is promptly and correctly combined with a high speed moire method.SELECTED DRAWING: Figure 1

Ri Shien

Papers

High speed displacement/strain distribution measurement method by moire method and measurement device