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Methods and systems for signal processing in particle detection systems

  • US 7,242,009 B1
  • Filed: 06/22/2005
  • Issued: 07/10/2007
  • Est. Priority Date: 06/22/2005
  • Status: Active Grant
First Claim
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1. A method of using laser-induced fluorescence to distinguish (a) a presence of threat particles interspersed with background particles from (b) an absence of threat particles, the threat particles representing fluorescent biological substances, comprising:

  • using a multiple-wavelength detection-band laser-induced fluorescence sensor to acquire a measurement set of particles for laser-induced fluorescence analysis, the sensor providing threat-present and threat-absent particle signals in response to the acquired measurement set of particles;

    defining a grey-scale weighting function formulated on competing sensitivity and false positive rate factors, the sensitivity factor representing sensitivity of detecting threat particles against non-threat particles and the false positive rate factor representing a probability of falsely concluding that the acquired measurement set of particles contains threat particles;

    using the weighting function to assign weights to particles in the measurement set, based on a numerical characterization of a particle and a weight associated with that characterization;

    assigning weights to each particle in the measurement set, based on the weighting function; and

    processing the weights assigned to the particles and producing an indication whenever a result obtained from the processing of the weights represents a likelihood of concluding correctly that the measurement set of particles contains threat particles.

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