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Apparatus and method for phase resolved fluorescence lifetimes of independent and varying amplitude pulses

  • US 5,317,162 A
  • Filed: 09/09/1992
  • Issued: 05/31/1994
  • Est. Priority Date: 05/23/1991
  • Status: Expired due to Term
First Claim
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1. An instrument to measure phase fluorescence lifetimes of signals representative of characteristics of subpopulations of particles by determining phase shift between a reference signal and emissions from the particles, the instrument comprising:

  • delivery means for moving particles through an interrogation window of the instrument;

    a source of modulated light at a predetermined frequency, the source positioned to direct and focus the modulated light onto individual particles in the window;

    detection means responsive to emissions from the individual particles illuminated by the source of modulated light, the detection means for generating an output signal;

    means for filtering the output signal and producing a filtered signal thereby passing a frequency band centered at the modulation frequency;

    an amplifier for setting the signal level above a preset level thereby producing a filtered, amplified signal;

    a limiting circuit to limit the filtered, amplified signal thereby producing a limited signal;

    a filter to remove from the limited signal, harmonics above the modulation frequency and an envelope below a preset frequency thereby producing a filtered limited signal, anda mixer to mix the filtered limited signal with a reference signal thereby relating the reference signal and the filtered limited signal to determine the relative phase shift of the fluorescence emissions.

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