Abstract: An integrated particle detection apparatus for optical detection of particles in an air stream. The particle detection apparatus includes a scalper for removing large particles from the air stream, a concentrator for separating out small particles and increasing the concentration of particles of interest, and a fluorescence sensor system for detecting the particles present in the air stream. The scalper, concentrator and sensor may include a single integrated unit, such that the scalper is fluidly contiguous with the concentrator and the concentrator is fluidly contiguous with the sensor.

Abstract: A particle separation apparatus is disclosed. The particle separation apparatus may be for sample air stream preparation and delivery in particle detection systems. The particle separation apparatus may include a first vortex separator coupled to a second vortex separator for selecting particles in the air stream that are within a desirable size range for particle detection. The second vortex separator may further increase the concentration of particles within the desirable size range per unit volume. The particle separation apparatus may deliver the size-selected air stream to a detector, such as a laser-induced fluorescence detection system.

Abstract: Fluid-based particle detection exhibits improved light collection and image quality from a light collection system that uses immersed optics on a flow-through cell for collecting and detecting scattered light from particles carried by the fluid. The flow-through cell includes first and second body sections that are coupled to form a unitary article and have opposed interior surface portions configured to form opposed walls of a flow channel through which the fluid flows. First and second optical elements are associated with the respective first and second body sections. In certain embodiments, at least one of the first and second optical elements is an integral part of its associated body section. A lens element constructed as an integral part of the unitary flow-through cell eliminates additional interfaces or bonding joints that cause scattering and absorption of light.

Abstract: A method for statistically distinguishing between two or more populations, such as between samples containing background and threat particles, is disclosed. According to one embodiment, the method for statistically distinguishing is a method for processing a signal in a particle detection system. The method may include characterizing each particle detected by a signal vector. The method may further include calculating a weight of each particle detected using a weighting function of the signal vectors. The weighting function may be a functional of a threat particle probability distribution and a background particle probability distribution. The method may also include summing a total weight of all particles tested and generating an alarm signal if the total weight exceeds an alarm level.

Abstract: A mixer for analytical application mixes a container of fluid without a magnetic stir bar. A device for testing a liquid for particles can use the mixer. The mixing can occur in a sealed container, and liquid can be transmitted to the device from the sealed container.

Abstract: An integrated particle detection apparatus for optical detection of particles in an air stream. The particle detection apparatus includes a scalper for removing large panicles from the air stream, a concentrator for separating out small particles and increasing the concentration of particles of interest, and a fluorescence sensor system for detecting the particles present in the air stream. The scalper, concentrator and sensor comprise a single integrated unit, such that the scalper is fluidly contiguous with the concentrator and the concentrator is fluidly contiguous with the sensor.

Abstract: Fluid-based particle detection exhibits improved light collection and image quality from a light collection system that uses immersed optics on a flow-through cell for collecting and detecting scattered light from particles carried by the fluid.

Abstract: A light-extinction-type optical particle detection system comprises a laser producing a beam in response to a drive current amplitude reaching a lasing threshold, a view volume, and a light-extinction detector. The beam is characterized by mode-hopping noise energy produced by spurious switching of laser operating modes. The system comprises a signal generator producing the drive current such that its amplitude transitions across the threshold by a selected amount and at a selected frequency to cause the beam to operate simultaneously in multiple modes. The selected amount and frequency cooperate to spread the mode-hopping noise energy over a spectral range established by the number of modes, such that the detector does not appreciably respond to the mode-hopping noise energy.