Tsi, Inc.

Peter P Hairston

Frank D Dorman

Stanley L Kaufman

Frederick R Quant

James L Blesener

Jugal K Agarwal

Gilmore J Sem

David B Blackford

Tyler Beck

Darrick L Niccum

Dahu Qi

Jim Evenstad

Darrick Niccum

An apparatus and method for improving aerosol particle characterization and detection accuracy in clean room applications that includes an optical particle sizer that receives a particle containing aerosol sample at a higher flow rate which is operatively coupled to an inertial aerosol concentrator for concentrating particles received from the optical particle sizer and delivering a lower flow rate, particle enriched output. The system further includes an optical sensor for sensing of intrinsic particle fluorescence of the lower, particle-enriched flow, since intrinsic fluorescence is a useful indicator of biological particles and biological particle viability, including bacterial particles. The system as a whole provides a measure derived from a single inlet flow both of total particles and of viable microbial particles based on their spectroscopic properties.

Apparatus and system for simultaneously measuring particle concentration and biocontaminants in an aerosol particle flow

Particle analyzing systems with fluorescence detection are disclosed, primarily in connection with particle sizing based on scattered light intensity or time-of-flight measurement. In one system, emission of fluorescence is used as a threshold for selecting particles for further analysis, e.g. mass spectrometry. In another embodiment, laser beams arranged sequentially along an aerosol path are selectively switched on and off, to increase the useful life of components, and diminish the potential for interference among several signals. Other embodiments advantageously employ color discrimination in aerodynamic particle sizing, single detectors positioned to sense both scattered and emitted fluorescent radiation, and laser beam amplitude or gain control to enhance the range of fluorescence detection.

Analysis systems detecting particle size and fluorescence

An electro-optical aerosol characterizing system includes a continuous wave laser for generating two beams in the red wavelength range, intersecting a particle stream at slightly spaced apart locations. A pulsed UV laser generates a beam that intersects the particle stream at a third location downstream. Laser energy scattered by each particle as it passes the first two locations, is used to compute aerodynamic sizes and UV laser pulsing times, so that in each case the UV beam irradiates the particle at the downstream location. Particles containing biological materials or other fluorescing components emit fluorescence signals in response to the irradiation. Accordingly, the system provides information about particle composition as well as particle size.

System for detecting fluorescing components in aerosols

An aerodynamic particle size measuring device includes a laser energy source and beam splitting, shaping and polarizing optics for forming two parallel, peripherally overlapping beams. The beams are caused to intersect a gas stream perpendicular to the direction of gas flow, thus to form a measuring volume at the intersection of the beams and flow. Single particles are carried through the measuring volume with the gas flow, each particle scattering and extinguishing light according to the beam profile, as predetermined by the degree of beam overlap and the Gaussian intensity distribution of each beam. A photodetector, responsive either to scattered light or light extinction, generates a time-dependent voltage profile that tends to replicate the intensity profile. The resulting electrical signal is processed to determine an amplitude, set a threshold for minimally acceptable amplitudes, and to derive two negative-going zero crossings for an unambiguous time/velocity determination. Logic circuitry employs the threshold in combination with the zero crossings to reject velocity readings based on single trigger or coincidence events.

Apparatus for measuring particle sizes and velocities

A particle flux counter apparatus utilizing light extinction. The apparatus utilizes two oppositely disposed cylindrical mirrors (21a, 21b) to bounce a beam back and forth between them, the beam traversing the length of the cylindrical mirrors (21a, 21b) in incremental steps. A plane mirror (22) is cooperatively located to reflect the beam back between the system to traverse the length of the cylindrical mirrors (21a, 21b) a second time in incremented steps. The two sets of steps interleaving such that the beam forms a sheet of light. A detector (60) monitors the intensity of the beam. As particles in a sample aerosol intersect the beam, the light is extinguished and the beam intensity changes. The detector (60) transmits a signal to a microprocessor (108) analyzation. The apparatus also utilizes a feedback circuit (300) to regulate the beam intensity and alternatively provides for modulating the beam to provide for higher peak power into the detector (60) and elimination of common mode noise.

Growing community of inventors

Saint Paul, MN, United States of America

Peter P Hairston