Abstract: Two arrangements are disclosed to provide high resolution measurement of sub-micrometer and micrometer particle size distributions. In a first arrangement, scattered light is measured over a wide range of scattering angles. At the same time, light scattered at low scattering angles is measured with high angular resolution. In the second arrangment, an improved Polarization Intensity Differential Scattering (PIDS) measurement is made possible by providing an interrogating light beam of selected wavelength including a first component having a linear polarization plane and a second component having a differential linear polarization plane, wherein the linear polarizations of the components are orthogonal. Photodetecting arrays in one or more scattering planes detect light scattered by the particles at least at two scattering angles.

Abstract: Methods and apparatus for measuring the intensity of light scattered by particles suspended in a sample volume illuminated by an interrogating light beam directed along an input axis, utilizing plural Fourier optical systems having lenses arranged for illuminating multiple photodetectors. The lenses of each Fourier optical system can be of different optical powers, for providing low power and high power optical trains. A low power optical train provides high resolution measurements of light scattered within a small angular range at low angles relative to the input axis, while a high power optical train provides lower resolution measurements of light scattered within a larger angular range at higher angles.

Abstract: Two arrangements are disclosed to provide high resolution measurement of sub-micrometer and micrometer particle size distributions. In a first arrangement, scattered light is measured over a wide range of scattering angles. At the same time, light scattered at low scattering angles is measured with high angular resolution. In the second arrangement an improved Polarization Intensity Differential Scattering (PIDS) measurement is made possible by providing an interrogating light beam of selected wavelength including a first component parallel to the scattering plane and a second component perpendicular to the scattering plane. Photodetecting arrangements detect light scattered by the particles at least at two scattering angles.

Abstract: An apparatus and method which provides a measure of the size distribution of particles dispersed in a fluid based upon an optimum combination of CLS measurements and DLS measurements. The measurement is characterized by relatively high resolution particle sizing. DLS data representative of the autocorrelation function, or power spectrum, of the detected intensity of scattered light for m measurement conditions of a sample, is optimally combined with CLS data representative of the average total detected intensity of scattered light for n measurement conditions, to provide an angle-independent, high resolution size distribution v(r), where m.gtoreq.1, n.gtoreq.0, m+n.gtoreq.2, and at least two of the measurement conditions are different. The size distribution may be expressed in terms of the continuous function v(r) or the histogram v, and may represent distributions weighted by mass, volume, number, surface area, or other measures.

Abstract: An apparatus and method which provides a measure of the size distribution of particles dispersed in a fluid based upon an optimum combination of CLS measurements and DLS measurements. The measurement is characterized by relatively high resolution particle sizing. DLS data representative of the autocorrelation function, or power spectrum, of the detected intensity of scattered light at a plurality of angles about a sample, is optimally combined with CLS data representative of the average total detected intensity at those angles, to provide an angle-independent, high resolution size distribution v(r). The size distribution may be expressed in terms of the continuous function v(r) or the histogram v, and may represent distributions weighted by mass, volume, number, surface area, or other measures.

Abstract: A light scattering interfacial tension spectrometer has a laser source of light directed, as an incident beam I.sub.i, through a focusing lens and a diffraction grating. The grating divides the incident beam I.sub.i into a main beam I.sub.m, undiffracted light, and a higher order, diffracted light, reference beam I.sub.r. The beam I.sub.r is passed through an attenuator and a diffraction focusing lens to a region under test, such as a liquid surface. The main beam I.sub.m, from the grating is transmitted through the common diffraction focusing lens to the test region where it is reflected. The reference beam I.sub.r is reflected from the test surface together with scattered light I.sub.s, and directed through an aperture to a photomultipler tube. The output of the photomultiplier is coupled to a pulse amplifier-discriminator and a photon correlator. For a liquid surface under test the output of the spectrometer provides a measure of the surface tension and the viscosity of the liquid.