Method and apparatus for measuring the displacements of particle images for multiple exposure velocimetry
First Claim
1. A method of measuring the displacement of compact images comprising the steps of:
- (a) providing a source of spatially separated compact images, said images having intensity distribution;
(b) compressing the images in separate, one-dimensional X and Y directions, including integrating the image intensity in said X and Y directions to produce respective electrical signals;
(c) analyzing the electrical signals resulting from the separate one dimensional compressions to determine the X and Y image displacements respectively.
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Abstract
A hybrid optical/digital method for measuring the displacements of compact images, in particular, particle images recorded on photographic or other recording media in multiple exposure photography. The method compresses the two-dimensional image field of the particles into two one-dimensional line images that are perpendicular to each other. The mean particle displacement between multiple exposures is determined by digitizing the one dimensional images, computing their autocorrelations, and locating the peaks of those autocorrelations. This method is particularly adapted to measure the velocity fields in fluids containing many small particles. Alternatively, when the first and second images of a single particle are the only images in the image field, the displacement is found by locating the peak of each image.
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Citations
20 Claims
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1. A method of measuring the displacement of compact images comprising the steps of:
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(a) providing a source of spatially separated compact images, said images having intensity distribution; (b) compressing the images in separate, one-dimensional X and Y directions, including integrating the image intensity in said X and Y directions to produce respective electrical signals; (c) analyzing the electrical signals resulting from the separate one dimensional compressions to determine the X and Y image displacements respectively. - View Dependent Claims (2)
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3. A method of measuring the displacement of compact images comprising the steps of:
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(a) periodically illuminating a record medium containing said images with a light beam; (b) splitting the images into two individual images along the X and Y directions respectively; (c) forming compressed images by projecting the individual images onto respective linear diode arrays; (d) measuring the compressed images using integration by linear detector arrays to yield resulting detector array output signals; and (e) analyzing the resulting detector array output signals to determine the X and Y image displacements respectively. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10)
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11. A system of measuring the displacement of compact images comprising:
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(a) means for providing a source of spatially separated compact images, said images having intensity distribution; (b) means for compressing the images in separate, one-dimensional X and Y directions, including means for integrating the image intensity in said X and Y directions to produce respective electrical signals; and (c) means for analyzing the electrical signals resulting from the separate one-dimensional compressions to determine the X and Y image displacements respectively. - View Dependent Claims (12)
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13. A system of measuring the displacement of compact images comprising:
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(a) means for periodically illuminating a record medium containing said images with a light beam; (b) means for splitting the images into two individual images along the X and Y directions respectively; (c) means for forming compressed images by projecting the individual images onto respective linear diode arrays; (d) means for measuring the compressed images using integration by said linear detector arrays to yield resulting detector array output signals; and (e) means for reading the resulting detector array output signals. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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Specification