Patent ID: 6061131
Filing Date: 2000-05-09
Classification: G01N

Abstract:
A light scattering particle size distribution measuring apparatus comprising:a light source for providing a beam of light along an optical axis;a sample cell for holding a specimen and receiving the beam of light for scattering and/or diffraction by particles in the specimen;a detector assembly including a first set of detector elements for receiving the scattered and/or diffracted light from the sample cell, a second set of detector elements positioned in a common plane between the first set of detector elements and a third centroid detector element for positioning on the optical axis, the first set of detector elements extend radially outward from the optical axis and are radially spaced from each other with a radially innermost detector element positioned adjacent the third centroid detector element to enable a measurement of relatively large diameter particles, the second set of detector elements are spaced about the third centroid detector element;a scattering and/or diffracting target member removably positioned on the optical axis, between the light source and the detector assembly, at a predetermined position to provide a predetermined diffraction pattern to the detector assembly to contact the second set of detector elements when aligned on the optical axis;means for automatically moving the target member onto the optical axis for a calibration operation;means for moving one of the light source and the detector assembly to align them on the optical axis;first means for providing a measurement of the particle size distribution from output signals of the first set of detector elements when the scattering and/or diffracting target member is removed from the optical axis;second means for measuring the predetermined scattered and/or diffraction pattern from output signals of the second set of detector elements when the scattering and/or diffracting target member is positioned on the optical axis to enable a movement of one of the light source and the detector assembly to align them on the optical axis, andmeans for automatically moving the target member off of the optical axis after the calibration operation.