| 摘要 |
PURPOSE:To enable highly accurate measurement at low cost, by measuring the flow speed of a fluid by using the incoherent measuring light of a light emitting diode. CONSTITUTION:A light pervious window 5 is provided to the wall body of a pipe 4 and measuring light 7 from a light emitting diode 6 is guided to a case 6 by optical fibers 8, 9. Output lights of the optical fibers 8, 9 are condensed to measuring points A, B in the pipe 4 through a microlens 11 and the window 5. Herein, a pair of reflected lights, generated when fine particles in a fluid 3 pass the points A, B, are condensed to an optical fiber 13 through the lens 11 and a concave lens 12 and guided to a photoelectric converter 14. Reflected light, generated when fine particles pass the point A, reflected light, generated when said fine particles pass the point B, are inputted to the converter 14. These reflected lights are converted to electric pulse signals by the converter 14 to be inputted to a measuring circuit 15 and the time difference of reflected light generation time at the point A and that at the point B is measured. Because the distance between the points A, B is predetermined, the speed of fine particles is operated from the quotient of these times and a flow speed is calculated on the basis of this speed. |
