Patent ID: 6587208
Filing Date: 2003-07-01
Classification: G01N,G01P

Abstract:
A method of measuring a diameter, distribution and so forth of micro gas bubbles, said method comprising the steps of:applying a sheet-shaped parallel laser beam to a liquid space in which micro gas bubbles are floating; capturing out-of-focus images of micro gas bubbles irradiated with the laser beam from a lateral direction which is at an angle &thgr; to a direction of travel of the laser beam; measuring the number N of interference fringes in the out-of-focus image corresponding to each micro gas bubble; and determining a diameter D of the micro gas bubble from the following relationship: D=(2&lgr;N/n&agr;)[cos(&thgr;/2)âˆ’sin(&thgr;/2)Ã·{square root over ( )}{n2+1âˆ’2n cos(&thgr;/2)}]âˆ’1â€ƒâ€ƒ(4) where &lgr; is a wavelength of the laser beam; &agr; is an angle subtended at the micro gas bubble by an objective lens used to capture the image of the micro gas bubble; and n is a relative index of refraction of a liquid in which the micro gas bubble is present.