Apparatus and method for determining the size and velocity of particles, droplets, bubbles or the like using laser light scattering

An apparatus for determining the direction of motion of a particle, droplet, bubble or the like, employing laser light scattering, comprising:

• laser generation means for providing first and second laser beams;
• light directing means for directing said laser beams along an axis and for causing said beams to cross said axis at a given angle to establish an interference pattern between said pair of beams;
• collection means for sensing the scattered interference signal of said pair of laser beams caused by said particle, droplet, bubble or the like passing through said interference pattern;
• signal phase determining means for determining the phase of said scattered signal sensed by said collection means as said particle, droplet, bubble or the like passes through said interference pattern;
• direction determining means coupled to said signal phase determining means for determining the direction of motion of said particle, droplet, bubble or the like from phase changes of said scattered signal;
• whereby the direction of motion of a particle, droplet, bubble or the like is determined from the phase of said scattered signal.

A method for sizing a particle, droplet, bubble or the like, employing laser light scattering, comprising the steps of:

• generating first and second laser beams;
• directing said first and second laser beams along an axis, and causing said beams to cross said axis at an angle to establish a sample volume between said pair of laser beams;
• sensing the scattered signal of said pair of laser beams caused by a particle, droplet, bubble or the like passing through said sample volume;
• determining the phase of said scattered signal as said particle, droplet, bubble or the like passes through said sample volume;
• determining the size of said particle, droplet, bubble or the like from phase changes in said scattered signal;
• whereby the size of a particle, droplet, bubble or the like is determined from the phase changes of said scattered signal.

A method for determining the direction of motion of a particle, droplet, bubble or the like, employing laser light scattering, comprising the steps of:

• generating first and second laser beams;
• directing said first and second laser beams along an axis, and causing said beams to cross said axis at an angle to establish a sample volume between said pair of laser beams;
• sensing the scattered signal of said pair of laser beams caused by said particle, droplet, bubble or the like passing through said sample volume;
• determining the phase of said scattered signal as said particle, droplet, bubble or the like passes through said sample volume;
• determining the direction of motion of said particle, droplet, bubble or the like from phase changes in said scattered signal;
• whereby the direction of motion of a particle, droplet, bubble or the like passing through said sample volume is determined.