Method and apparatus for determining particle characteristics utilizing a plurality of beam splitting functions and correction of scattered light

A method for determining particle characteristics comprising:

• a) illuminating at least one particle,
• b) at least one performance of detecting light,
• c) at least one performance of a first beam splitting, wherein said first beam splitting occurs in a path of light between said light source and said particles,
• d) at least one performance of a second beam splitting, wherein said second beam splitting occurs in the path of scattered light between said particles and said detector, wherein said scattered light is scattered from said particles, wherein light derived from said first beam splitting is combined with scattered light by said second beam splitting and wherein said detecting measures said combined light to create an optical interference light detecting signal which is derived from motion of said particles,
• e) determining particle characteristics from said light detecting signal.

A method for correcting a detector signal or a function of a detector signal, wherein said signal is derived from combination of particle scattered light with light from an illumination means to produce an optical interference signal on said detector, wherein said correcting generally reduces components of said signal or said function which are not caused by light scattered from particles of interest, comprising utilizing at least two steps from the group consisting of steps (a) through (h), and step (i) and step (j):

• a) measuring a first scatter detector signal, as a function of time, with particles in a volume of dispersant which volume is viewed by said detector,
• b) calculating a first function of said first scatter detector signal,
• c) measuring a second scatter detector signal, as a function of time, with generally no particles of interest in a volume of dispersant which volume is viewed by said detector,
• d) calculating a second function of said second scatter detector signal,
• e) measuring a third signal, as a function of time, from a detector which monitors a signal which is proportional to a light flux of an illuminating means, the third signal being derived while said first scatter detector signal is measured,
• f) calculating a third function from said third signal,
• g) measuring a fourth signal, as a function of time, from a detector which monitors a signal which is proportional to a light flux of an illuminating means, the fourth signal being derived while said second scatter detector signal is measured,
• h) calculating a fourth function from said fourth signal,
• i) utilizing at least one item selected from the group consisting of a signal correction and a function correction, wherein said signal correction utilizes said first scatter detector signal and at least one of the group consisting of said third detector signal, mean value of said first scatter detector signal, and mean value of said third detector signal, and wherein said function correction utilizes said first function and at least one item selected from the group consisting of said second function, said third function, said fourth function, mean value of said first scatter detector signal, mean value of said third detector signal, said first scatter detector signal, said second scatter detector signal, said third detector signal, said fourth detector signal, and total power in at least one frequency band for at least one of the group consisting of said first scatter detector signal and said second scatter detector signal, wherein said function correction does not consist of only subtracting said second function from said first function, and
• j) determining particle information from said corrected function or corrected signal, wherein each of said calculated or corrected functions comprises a power spectrum or autocorrelation function.