US 11,789,166 B2
Pulse counting coincidence correction based on count rate and measured live time
Susanne Vera Hering, Berkeley, CA (US); Gregory Stephen Lewis, Berkeley, CA (US); Steven Russel Spielman, Oakland, CA (US); and Mark R. Stolzenberg, Minneapolis, MN (US)
Assigned to Aerosol Dynamics Inc., Berkeley, CA (US)
Filed by Aerosol Dynamics Inc., Berkeley, CA (US)
Filed on Jun. 24, 2020, as Appl. No. 16/911,368.
Claims priority of provisional application 62/866,233, filed on Jun. 25, 2019.
Prior Publication US 2020/0408931 A1, Dec. 31, 2020
Int. Cl. G01N 15/02 (2006.01); G01T 1/17 (2006.01); G01T 1/172 (2006.01); G01N 15/06 (2006.01); G01N 15/14 (2006.01)
CPC G01T 1/171 (2013.01) [G01N 15/0205 (2013.01); G01N 15/0211 (2013.01); G01N 15/065 (2013.01); G01N 15/1459 (2013.01); G01T 1/172 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method for detecting particles, comprising:
directing a flow of gas or liquid containing particles through a sensing region illuminated by a light source;
detecting light scattered by the particles as they pass through the sensing region, the detecting comprising capturing a light intensity signal comprised of multiple pulses above a threshold level, each pulse comprising in indication of light scattered by one or more particles;
counting distinct pulses during a measurement period, each distinct pulse the signal crossing from below the threshold level to above the threshold level;
measuring a measured live time over the measurement period, the measured live time comprising a length of time the signal is below the threshold level; and
outputting a coincidence-corrected value comprising a number of particles that passed through the sensing region during the measurement period, the coincidence-corrected value calculated by dividing a number of distinct pulses counted by a first quantity, the first quantity comprising the measured live time, minus a second quantity, the second quantity comprising a constant multiplied by the number of distinctly counted pulses, where the constant is determined by comparing the number of distinct pulses against a number of distinct pulses in a known concentration to derive a mean time period added to each distinct pulse before detecting a next particle as a distinct event and has the units of time.