Abstract: An apparatus and method are disclosed for determining electrophoretic mobility using scattering light phase analysis comprising emitting a laser light along a path and transmitting a first portion of the laser light and reflecting a second portion of the laser light. The apparatus and method can also comprise deflecting one of the first and second portions of the laser in response to a drive signal, holding a sample to receive at least one of the first and second portions of the laser light under an electric field and output a composite light wave, outputting a photopulse signal based on the composite light wave, and measuring the electrophoretic mobility of the sample based on a phase shift analysis using cross-correlation of the photopulse signal with the drive signal.

Abstract: A single-particle optical sensor, which has high sensitivity and responds to relatively concentrated suspensions, uses a relatively narrow light beam to illuminate an optical sensing zone nonuniformly. The zone is smaller than the flow channel so that the sensor responds to only a fraction of the total number of particles flowing through the channel, detecting a statistically significant number of particles of any relevant diameter. Because different particle trajectories flow through different parts of the zone illuminated at different intensities, it is necessary to deconvolute the result. Two methods of deconvolution are used: modified matrix inversion or successive subtraction. Both methods use a few basis vectors measured empirically or computed from a theoretical model, and the remaining basis vectors are derived from these few. The sensor is compensated for turbidity. Several embodiments are disclosed employing light-extinction or light-scattering detection, or both.

Abstract: A single-particle optical sensor, which has high sensitivity and responds to relatively concentrated suspensions, uses a relatively narrow light beam to illuminate an optical sensing zone nonuniformly. The zone is smaller than the flow channel so that the sensor responds to only a fraction of the total number of particles flowing through the channel, detecting a statistically significant number of particles of any relevant diameter. Because different particle trajectories flow through different parts of the zone illuminated at different intensities, it is necessary to deconvolute the result. Two methods of deconvolution are used: modified matrix inversion or successive subtraction. Both methods use a few basis vectors measured empirically or computed from a theoretical model, and the remaining basis vectors are derived from these few. The sensor is compensated for turbidity. Several embodiments are disclosed employing light-extinction or light-scattering detection, or both.

Abstract: A single-particle optical sensor, which has high sensitivity and responds to relatively concentrated suspensions, uses a relatively narrow light beam to illuminate an optical sensing zone nonuniformly. The zone is smaller than the flow channel so that the sensor responds to only a fraction of the total number of particles flowing through the channel, detecting a statistically significant number of particles of any relevant diameter. Because different particle trajectories flow through different parts of the zone illuminated at different intensities, it is necessary to deconvolute the result. Two methods of deconvolution are used: modified matrix inversion or successive subtraction. Both methods use a few basis vectors measured empirically or computed from a theoretical model, and the remaining basis vectors are derived from these few. The sensor is compensated for turbidity. Several embodiments are disclosed employing light-extinction or light-scattering detection, or both.

Abstract: An automatic dilution system and method provides optimal dilution factor DF for a sample suspension containing particles mixed with a diluent. A diluent flows into a mixing chamber, and the sample is injected into the chamber. A sensor, such as a single particle optical sensor (SPOS), measures the value of a particular characteristic, which characteristic Rmax(0) is the initial rate of increase of a quantity related to particle concentration. A CPU/Controller calculates from Rmax(0) the optimal value of DF, and develops a control signal which adjusts the flow of the sample to provide the optimal value of DF. In a first embodiment, all of the diluted sample passes through the sensor. In a second embodiment, only a portion of the sample is directed through the sensor to shorten the time to reach equilibrium. The time to reach equilibrium is further reduced in a third embodiment in which the mixing means is a static mixer, having relatively small volume, inserted in series with a diluent flow tube.

Abstract: An optical sensor for counting and sizing particles, including a light extinction (LE) signal representative of the particles, and a light scattering (LS) signal representative of the particles. The light scattering signal and the light extinction signal are combined to form a single composite signal. The single composite signal has a substantially similar output to the light extinction (LE) signal for particle sizes in an upper range of particle sizes typically measured by the light extinction sensor. The single composite signal has a substantially similar output to the light scattering (LS) signal for particle sizes in a lower range of particle sizes typically measured by the light scattering sensor. The single composite signal has an output representing the combined light extinction (LE) signal and light scattering (LS) signal for particle sizes in a middle range of particle sizes.