Abstract: An L2F velocimeter comprises a probe for insertion into a fluid, the probe having an open area therein to allow the fluid to pass through. The probe comprises an illumination system to direct a pair of light beams, separated by a distance, through the open area, and a collection system to collect forward scattered light scattered from particles in the fluid. The collection system has an optical axis in common with the illumination system. The velocimeter further comprises an electro optical assembly connected to the probe to provide light to the illumination system, to receive light collected from the collection system, to measure a lapse time in fluctuations of the forward scattered light created by particles passing through the pair of light beams and to calculate the velocity of the fluid based on the lapse time and the separation distance.

Abstract: An L2F velocimeter comprises a probe for insertion into a fluid, the probe having an open area therein to allow the fluid to pass through. The probe comprises an illumination system to direct a pair of light beams, separated by a distance, through the open area, and a collection system to collect forward scattered light scattered from particles in the fluid. The collection system has an optical axis in common with the illumination system. The velocimeter further comprises an electro optical assembly connected to the probe to provide light to the illumination system, to receive light collected from the collection system, to measure a lapse time in fluctuations of the forward scattered light created by particles passing through the pair of light beams and to calculate the velocity of the fluid based on the lapse time and the separation distance.

Abstract: An optical system design for measuring the velocity of fluids flowing through pipes or other conduits is disclosed. The optical system is comprised of a means for delivering two beams through a window in the wall of the pipe, focused to two points aligned along an axis of the pipe and separated by a known distance, and means for detecting light that is scattered by particles carried in the fluid stream through a second window, that is disposed on the opposite side of the pipe. By measuring the time delay between detected signals, the velocity of the fluid can be determined. The delivered light beams are focused in a shallow cone of light and are blocked by an obstruction disposed behind the second window. The scattered light passes through an aperture behind the second window that surrounds the obscuration, and is focused on to a detector surface.

Abstract: The invention provides a fiber optic sensing system for use in environments hostile to electronics. The system comprises an optical module comprising a light source and a photodetector, a probe comprising a glass optical fiber core, preferably with a transducer sensitive to the measurement parameter coupled thereto, an extension comprising a plastic optical fiber core, a first connector configured to optically couple the extension to the probe and a second connector configured to optically couple the extension to the optical module. Light emitted from the light source is transmitted to the transducer on the probe and returned to the photodetector by the extension.