Abstract: Apparatus and method wherein particles in a liquid stream are hydrodynamically focused to pass through an impedance sensing orifice, a low frequency current source provides a current through the orifice to produce a signal representative of the particle's size, a high frequency source provides a current through the orifice to produce a signal representative of the particle's size and internal resistance, a detector determines the particle's length, and a digital computer correlates the signals for each particle and calculates its shape factor, degree of deformation or natural shape, true volume and internal resistivity.

Abstract: An apparatus and method for illuminating particles, wherein a source of illumination provides a beam of illuminating radiation which perpendicularly intersects a stream of liquid having the particles suspended therein. The illuminator apparatus comprises a concave reflector surface having a center of curvature and an optical axis which is disposed perpendicularly relative to the stream and with the beam being positioned thereon. The stream of liquid defines a cylindrical lens having a focus positioned at the center of curvature. In operation, the illuminating radiation illuminates the particles, is refracted by the stream so as to converge to a focus, passes from that focus to a concave reflector surface, and reflects from the concave reflector surface back to the focus, so as to impinge upon the stream for a second time, to further illuminate the particles.

Abstract: A method and apparatus for correcting a particle pulse count subject to coincidence error is disclosed wherein particle pulses, developed in response to passage of particles in a particulate system through a sensing zone, are counted for a predetermined period of time. The predetermined period of time is increased or extended in response to each pulse counted by a time increment that is related to a characteristic of the counted pulse, such as the pulse width, duration, or amplitude. The total additional time period allows the counting of additional particle pulses such that the total count at the end of the extended time period is an error corrected count for the number of particles detected in the predetermined time period.

Abstract: A particle analyzer of the Coulter type has at least first and second sensing zone arrangements, each having substantially the same dimensions and each generating a train of particle pulses in response to passage through the respective sensing zone of a sample containing a plurality of particles to be counted. A summing circuit connected to the output of each sensing zone sums together each of the trains of particle pulses to develop a summed train of pulses. Additional circuitry is connected to each sensing zone and the summing circuitry. This circuitry is operative to change mathematically at least the number of particle pulses in the summed train of particle pulses. The mathematically changed summed train of pulses and the train of pulses from the first and second sensing zones then are accumulated to produce an error corrected particle pulse count.

Abstract: In both the method and system for clearing the debris from the aperture of a particle study device combinations of pulses of predetermined, waveform amplitude and frequency are developed and coupled through the conductive fluid passing through the particle study device aperture. The pulses cause the fluid in the aperture to vaporize and form a gas. The gas explodes away any debris clogging the aperture as it escapes from the aperture.

Abstract: A particle analyzer for obtaining a narrow distribution of particles suspended in a liquid wherein electric pulses are produced by moving the liquid through a sensing zone. The analyzer includes elements for differentiating the pulses, short circuiting to ground pulse portions of one state and measuring the heights of pulse portions of another state as indications of particle sizes.

Abstract: By creating at least two related raw counts N.sub.1 and N.sub.2, of particles in a fluid suspension either as two physcially derived particle counts, or one physical count and an artificial count derived from the physical count, there can be developed a mathematic function relationship by which the "scanning constant" K of a particle analyzer, for example of a Coulter type, can be factored out and a resultant equation obtained. The resultant equation is employable in operating upon the input N.sub.1 and N.sub.2 raw counts for generating the ultimately desired corrected particle count N.sub.0, which eliminates particle coincidence errors. The disclosure encompasses several methods and apparatuses by which the raw counts are developed and by which the related mathematic functions are defined and then employed to obtain corrected counts.

Abstract: An apparatus for determining the correct particle sizes at predetermined percentiles of the size distribution of a particulate system having a known size distribution characteristic such as for example a normal or log-normal size distribution, wherein a portion of the particles are too small to be measured. The particulate system is first passed through a particle detecting device which can be of the Coulter type. The particle detecting device produces particle pulses proportional to the size of the particles in the particulate system which can be measured. At least three percentile size determining circuits receive the particle pulses and develop first, second and third particle size signals respectively, indicating the size of the particles in the particulate system at the first, second and third predetermined percentiles.

Abstract: The electrical sensing circuitry includes a power supply and a signal-detecting circuit which are coupled through the resistance of an electrolyte in a liquid in an aperture of a particle-analyzing device between sensing electrodes positioned on either side of the aperture. The liquid containing an electrolyte and the passage of a liquidborne particle through the aperture causes a change in the resistance of the aperture thereby generating a signal which is detected by the signal-detecting circuit. The parameters of the circuit elements are chosen to provide circuit relationships which render the particle-generated signal independent of the diameter of the aperture. This is achieved by utilizing a power source having a low output impedance and a signal-detecting circuit which has a low input impedance for both D.C. and A.C., namely, at the signal frequencies of the signals sensed.

Abstract: A method and apparatus for correcting a particle pulse count subject to coincidence error is disclosed wherein particle pulses, developed in response to passage of particles in a particulate system through a sensing zone, are counted for a predetermined period of time. The predetermined period of time is increased or extended in response to each pulse counted by a time increment that is a function of a characteristic of the counted pulse, such as the pulse width, duration, or amplitude. The total additional time period allows the counting of additional particle pulses such that the total count at the end of the extended time period is an error corrected count for the number of particles detected in the predetermined time period.

Abstract: An apparatus which includes circuitry for automatically sampling each pulse in a series of pulses a predetermined average number of times, sequentially storing the samples for a period of time, and reproducing the pulses from the samples, delayed in time.A method of operation is encompassed within the invention as well as use of the above apparatus in a particle study device.