Micromeritics Instrument Corporation

William B Conklin

Michael Strickland

James P Olivier

Warren P Hendrix

Ronnie W Camp

An apparatus and method are disclosed for obtaining and analyzing light scattering data to determine the size distribution of a group of dispersed particles that scattered the light. The apparatus and method use a two-dimensional array of photosensitive pixels such as a charge-coupled device (CCD) or an array of solid-state photodiodes. The analyzer illuminates the particles with a dose of light in a collimated beam from a light source so as to scatter light of the beam, and at least a portion of the light interacting with the particles is detected with the photosensitive pixel array. The pixels are functionally equivalent and the analyzer dynamically configures and re-configures at least a portion of the pixels into a variable number of data collection areas which correspond to a selected set of scattering angles. The analyzer also determines whether and, from the pixel output data, where an unscattered center of the incident light beam intersects the pixel array. Thus, no precision mechanical alignment of the light source and the pixel array detector is required prior to operation of the analyzer. Furthermore, the ability of the analyzer to determine the unscattered beam center allows the analyzer to classify each of at least a portion of the pixels to data collection areas according to a function of the geometric relationship the pixel bears to the location of the beam center.

Apparatus and method for determining the size distribution of particles

The invention provides improvements in a system for carrying out volumetric sorption analysis of porous materials. According to one aspect of the invention, the saturation pressure of the adsorbate gas is measured after dosing of the sample during an actual run has brought the adsorbate gas to a saturation condition above the sample, and this measured saturation pressure is then used by the system to determine the relative pressures at which data will be taken during desorption. In accordance with another aspect of the invention, the system automatically adds extra adsorbate gas to the dosing manifold until the analysis proceeds beyond a selected relative pressure, so that far fewer doses are required to reach initial target relative pressures in the case of materials which adsorb large amounts of gas at low relative pressures.

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Lawrenceville, GA, United States of America

William B Conklin