Method and apparatus for measuring the displacements of particle images for multiple exposure velocimetry

A method of measuring the displacement of compact images comprising the steps of:

• (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.

A system of measuring the displacement of compact images comprising:

• (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.

A system of measuring the displacement of compact images comprising:

• (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.