Fast image processing with a microcomputer applied to speckle photography
Abstract
An automated image recognition system is described for speckle photography investigations in fluid dynamics. The system is employed for characterizing the pattern of interference fringes obtained using speckle interferometry. A rotating ground glass serves as a screen on which laser light passing through a specklegraph plate, the flow and a compensation plate (CP) is shone to produce a compensated Young's pattern. The image produced on the ground glass is photographed by a video camera whose signal is digitized and processed through a microcomputer using a 6502 CPU chip. The normalized correlation function of the intensity is calculated in two directions of the recorded pattern to obtain the wavelength and the light deflection angle. The system has a capability of one picture every two seconds. Sample data are provided for a free jet of CO2 issuing into air in both laminar and turbulent form.
- Publication:
-
Applied Optics
- Pub Date:
- November 1985
- DOI:
- 10.1364/AO.24.003838
- Bibcode:
- 1985ApOpt..24.3838E
- Keywords:
-
- Computer Techniques;
- Flow Visualization;
- Image Processing;
- Photography;
- Speckle Patterns;
- Autocorrelation;
- Diffraction Patterns;
- Jet Flow;
- Microcomputers;
- Refractivity;
- Instrumentation and Photography;
- SPECKLE PHENOMENA;
- FLOW;
- PATTERN RECOGNITION;
- IMAGE PROCESSING