Abstract: The method of measuring at least two distinct properties of a single particle comprising: a) accelerating a particle having a certain velocity in at least one acceleration region, the acceleration region being a region in which the velocity of the particle changes, to cause the velocity of the particle to vary; b) detecting a passage of the particle at each of three or more locations within or near an acceleration region; c) measuring a set of time-of-flight values for the particle, each time-of-flight value being equal to a time interval between the passage of the particle at two locations; and d) determining the values of at least two properties of the particle by comparing the set of time-of-flight values for the particle with calibration data.

Abstract: A method or device is useful for measuring at least two motion parameters of a particle for motion in at least one specified direction at or near at least one specified time and location, or determining from such measurements at least one motion parameter of a fluid element containing a particle for motion in at least one specified direction at or near at least one specified time and location, at least one property of a particle or of a fluid at or near at least one specified time and location, or at least one external force acting on a particle in a specified direction at or near at least one specified time and location.

Abstract: A new class of methods for characterizing particles is described along with associated apparatuses. These methods are called modulated dynamic light scattering (MDLS) methods because they utilize time and space modulations of the incident or scattered light as well as modulations caused by random Brownian motions of the particles, for example, to measure particular properties. The autocorrelation function of the scattered light signal from a particle is measured to provide a highly resolved signature even when the signal is buried in noise. The dynamics of the scattered light signal from a suspended particle undergoing random Brownian translations and rotations is analyzed to obtain the relationship of the particle's properties to its autocorrelation function signature. By comparison of the theoretical and measured functions, properties of a particle suspended in a (1) liquid, (2) gas, or (3) rarefied gas can be determined.

Abstract: A new class of methods for characterizing particles is described along with associated apparatuses. These methods are called modulated dynamic light scattering (MDLS) methods because they utilize time and space modulations of the incident or scattered light as well as modulations caused by random Brownian motions of the particles, for example, to measure particular properties. The autocorrelation function of the scattered light signal from a particle is measured to provide a highly resolved signature even when the signal is buried in noise. The dynamics of the scattered light signal from a suspended particle undergoing random Brownian translations and rotations is analyzed to obtain the relationship of the particle's properties to its autocorrelation function signature. By comparison of the theoretical and measured functions, properties of a particle suspended in a (1) liquid, (2) gas, or (3) rarefied gas can be determined.

Abstract: Apparatus, intended primarily for use in an aerodynamic particle sizing system, for generating a pair of closely-spaced light beams, each having a thin, elongated cross-sectional shape. Particle sizes are determined by directing a particle stream through the light beams and measuring the times of flight of particles between the two light beams. The apparatus for generating the light beams includes a laser source and beam forming optics. In one embodiment, a first light beam is formed at the particle stream by a cylindrical lens. After passing through the particle stream, the first light beam is reflected and focused to form a second light beam at the particle stream that is displaced from the first light beam. The first light beam can be reflected and focused by a concave cylindrical mirror or, alternatively, by a flat mirror and a convex cylindrical lens.

Abstract: Debris suppression is effected in a sealed disk unit, of the kind having a generally enclosed record element/cover sheet inter-space, by controlling the temperature gradient across the inter-space so that thermophoretic forces, exerted by air molecules, drive ablative debris particles toward the cover sheet.

Abstract: Suspended particles which may be small solids or liquid particles or particles consisting of both solid and liquid components or relatively heavy molecules suspended in a lighter suspending gas are formed into a continuum source particle beam upon expansion of the suspension through a nozzle into a vacuum environment. The flow of the particle containing gas into the nozzle is confined by a flow of clean, particle free gas, as between a core and a sheath thereof, such that the particles have the same position at the inlet of the nozzle or at some location downstream of the inlet, such as the exit of the nozzle, thereby allowing only those particles containing the trajectory corresponding to the selected particle properties to be transmitted through one or more collimator holes or skimmers which are disposed a sufficient distance from the nozzle exit. The particle properties which determine their trajectory are particle mass and dimensions.