Method and systems for determining drop delay using scatter signals across spatially separated lasers

A method for adjusting a droplet charge timing for a particle in a flow stream in a particle analyzer, the method comprising:

• irradiating in a cuvette a sample comprising the particle in the flow stream with a first laser in a first interrogation region within the cuvette and a second laser in a second interrogation region within the cuvette;
• detecting light from the particle in a first photodetector channel and a second photodetector channel;
• generating a first photodetector signal pulse in response to the light detected in the first photodetector channel;
• generating a second photodetector signal pulse in response to the light detected in the second photodetector channel;
• determining the first order moment of the first photodetector signal pulse and the second photodetector signal pulse;
• calculating a velocity for the particle in the flow stream based on the first order moment of the first photodetector signal pulse and the second photodetector signal pulse;
• determining the drop delay of the particle based on the calculated velocity for the particle;
• and
• adjusting the droplet charge timing for the particle based on the drop delay.

A method for adjusting a droplet charge timing for a particle in a flow stream in a particle analyzer, the method comprising:

• irradiating in a cuvette a sample comprising the particle in the flow stream with a first laser in a first interrogation region and a second laser in a second interrogation region and a third laser in a third interrogation region, wherein the distance between the first interrogation region and the second interrogation region is different from the distance between the second interrogation region and the third interrogation region;
• detecting light from the particle in a plurality of photodetector channels;
• generating a photodetector signal pulse in response to the detected light in each of the photodetector channels;
• calculating a velocity for the particle in the flow stream based on the photodetector signal pulses in two or more of the photodetector channels based on one or more of a distance between the first interrogation region and the second interrogation region, and a distance between the second interrogation region and the third interrogation region;
• determining the drop delay of the particle based on the calculated velocity for the particle;
• and
• adjusting the droplet charge timing for the particle based on the drop delay.