Image Number 4 for United States Patent #4919536.
A flow field seeded with small particles is illuminated by collimated, monochromatic laser light sheet 16. Doppler shifted scattering from particle motion is imaged by an optical system 22. An optical frequency-to-intensity converter 24 is located at the image plane such that the transmitted image contains a simultaneous two-dimensional measurement of flow velocity along a direction determined by a laser beam and observer (converter) direction. These images can be observed directly or through a TV-2-D array camera and monitor or processed through a computer system 28.