Measurement of statistical parameters of a distribution of suspended particles

Apparatus for measuring the mean of the area distribution of a collection of particles comprising:

• means for passing a light beam through said collection of particles,
• means for filtering the light diffracted from said beam through a first filter which transmits light flux diffracted from each particle proportional to the second power of its radius,
• means for filtering the light diffracted from said beam through a second filter which transmits light flux diffracted from each particle proportional to the third power of its radius,
• means for producing a first and second signal (X.sub.2 and X.sub.3, respectively) in response to the integral of the light flux detected passing through the respective first and second filters due to all of the particles of said collection,
• means for calculating the mean of the area distribution (M.sub.A) of the particles in said collection as a number proportional to the ratio X.sub.3 /X.sub.2.

Apparatus for measuring the mean of the volume distribution of a collection of particles comprising:

• means for passing a light beam through said collection of particles,
• means for filtering the light diffracted from said beam through a first filter which transmits light flux diffracted from each particle proportional to the third power of its radius,
• means for filtering the light diffracted from said beam through a third spatial filter which transmits light flux diffracted from each particle proportional to the fourth power of its radius,
• means for producing a first and second signal (X.sub.3 and X.sub.4, respectively) in response to the integral of the light flux detected passing through the respective first and second filters due to all of the particles of said collection,
• means for calculating the mean of the volume distribution (M.sub.v) of the particles in said collection as a number proportional to the ratio X.sub.4 /X.sub.3.

Apparatus for continuously measuring the mean of the area distribution, the mean of the volume distribution, and the standard deviation of the area distribution of a flowing sample of fluid suspended particles comprising:

• means for directing a light beam through said sample;
• means for sequentially filtering the light diffracted by said particles said means including a rotating mask having spaced thereon radially oriented spatial filters including
• a first spatial filter which transmits light flux diffracted from each particle proportional to the second power of its radius,
• a second spatial filter which transmits light flux diffracted from each particle proportional to the third power of its radius,
• a third spatial filter which transmits light flux diffracted from each particle proportional to the fourth power of its radius, and
• a stationary chopping blade operable to block the diffracted light in sectors other than that occupied by that one of the spatial filters as sequentially selected;
• means for producing a first, second and third signal (X.sub.2, X.sub.3 and X.sub.4, respectively) in response to the integral of the light flux detected passing through the respective first, second and third spatial filters due to all of the particles of said sample and summed over a predetermined time, and
• computer means for
• calculating the mean of the area distribution (M.sub.A) of the particles in said sample as a number proportional to the ratio X.sub.3 /X.sub.2,
• calculating the mean of the volume distribution (M.sub.v) of the particles in said sample as a number proportional to the ratio X.sub.4 /X.sub.3, and
• calculating the standard deviation of the area distribution of the particles in said sample as the square root of the product M.sub.A (M.sub.v -M.sub.A).

Apparatus for continuously measuring the mean of the area distribution of a flowing sample of fluid suspended particles comprising:

• means for directing a light beam through said sample;
• means for sequentially filtering the light diffracted by said particles said means including a rotating mask having spaced thereon radially oriented spatial filters including
• a first spatial filter which transmits light flux diffracted from each particle proportional to the second power of its radius,
• a second spatial filter which transmits light flux diffracted from each particle proportional to the third power of its radius, and
• a stationary chopping blade operable to block the diffracted light in sectors other than that occupied by that one of the spatial filters as sequentially selected;
• means for producing a first and second signal (X.sub.2 and X.sub.3, respectively) in response to the integral of the light flux detected passing through the respective first and second spatial filters due to all of the particles of said sample and summed over a predetermined time, and
• computer means for calculating the mean of the area distribution (M.sub.A) of the particles in said sample as a number proportional to the average value of ratio X.sub.3 /X.sub.2 over a predetermined period of time.