A method of counting particles (S1-S5) passing through a passageway, the method comprising: generating a first number of light channels at a defined spacing across the passageway transverse to a longitudinal axis of the passageway, the first number of light channels collectively defining a first light plane, each of the first number of light channels generated by a corresponding one of a first number of LED emitters disposed on a first side of the passageway, each of the first number of LED emitters having a known spacing and each producing a light intensity; with a first number of photodiodes disposed on a second side of the passageway and with each one of the first number of photodiodes disposed opposite to one of the first number of LED emitters, generating raw output signal values proportional to the light intensity of each of the first number of light channels; as the particles (S1-S5) pass through the first light plane, recording the raw output signal values generated across each of the first number of light channels in parallel relation over a series of sequential data scans, the raw output signal values (V raw) being stored in data cells within a first data set; normalizing the raw output signal values in each of the data cells of the first data set such that each data cell of the first data set has a Normalized Output Signal, NOS, value; the method being characterized in that it further comprises: analyzing the NOS values of each of the data cells of the first data set to identify data cells joined as a cluster by at least one NOS value within a predefined range of NOS values, each of the identified clusters of joined data cells of the first data set defining a separate first plane Event corresponding to at least one particle passing through the first light plane; identifying each said separate first plane Event with a unique first plane identifier; summing the NOS values of each said identified first plane Event; determining a group speed of each said identified first plane Event; determining for each said identified first plane Event, an Event Volume by multiplying the NOS value sum from step by said group speed from step for each said identified first plane Event; determining a particle count of each said identified first plane Event by characterizing the Event Volume. generating a first number of light channels at a defined spacing across the passageway transverse to a longitudinal axis of the passageway, the first number of light channels collectively defining a first light plane, each of the first number of light channels generated by a corresponding one of a first number of LED emitters disposed on a first side of the passageway, each of the first number of LED emitters having a known spacing and each producing a light intensity; with a first number of photodiodes disposed on a second side of the passageway and with each one of the first number of photodiodes disposed opposite to one of the first number of LED emitters, generating raw output signal values proportional to the light intensity of each of the first number of light channels; as the particles (S1-S5) pass through the first light plane, recording the raw output signal values generated across each of the first number of light channels in parallel relation over a series of sequential data scans, the raw output signal values (V raw) being stored in data cells within a first data set; normalizing the raw output signal values in each of the data cells of the first data set such that each data cell of the first data set has a Normalized Output Signal, NOS, value; analyzing the NOS values of each of the data cells of the first data set to identify data cells joined as a cluster by at least one NOS value within a predefined range of NOS values, each of the identified clusters of joined data cells of the first data set defining a separate first plane Event corresponding to at least one particle passing through the first light plane; identifying each said separate first plane Event with a unique first plane identifier; summing the NOS values of each said identified first plane Event; determining a group speed of each said identified first plane Event; determining for each said identified first plane Event, an Event Volume by multiplying the NOS value sum from step by said group speed from step for each said identified first plane Event; determining a particle count of each said identified first plane Event by characterizing the Event Volume.