Patent ID: 6369881
Filing Date: 2002-04-09
Classification: G01F,G01P

Abstract:
An optical flow sensor for measuring gas flow velocity in a predetermined direction of gas flow comprising:an optical transmitter that generates a collimated optical beam across said gas flow; an optical receiver including a plurality of receiving lenses all located in optical communication with said optical transmitter and in the path of said optical beam and separated from each other in a direction parallel to said predetermined direction of gas flow, a separate optical photodetector for each of said receiving lenses that produces an electronic output that varies in response to scintillations occurring in said optical beam, a separate signal-controlled gain amplifier circuit coupled to each of said optical photodetectors; a separate analog-to-digital converter coupled to each of said gain amplifier circuits for separately digitizing outputs from each of said gain amplifier circuits; and a digital signal processor coupled to receive inputs from all of said gain amplifier circuits to determine the temporal cross correlation of said digitized outputs for scintillation events detected separately by all of said photodetectors using a logarithmic time delay function of the differences of positive and negative time delays of the covariance function of said inputs to measure flow rate independent of both pressure and temperature of said gas flow, and to provide therefrom a path integrated flow rate in said predetermined direction of gas flow.