Methods for modulation and synchronous detection in a flow cytometer and systems for same

A particle analyzer for determining one or more parameters of a particle in a flow stream, the particle analyzer comprising:

• a light source comprising:
• a laser;
• an input polarizer;
• and
• an electro-optical modulator,
• wherein the light source is configured to generate a polarized frequency-modulated beam of laser light at a reference frequency;
• a flow cell for conveying the particle through the flow stream;
• an output polarizer;
• a light detection system comprising a photodetector configured to detect scattered light from an irradiated particle in the flow stream conveyed through the output polarizer;
• and
• a processor comprising memory operably coupled to the processor wherein the memory comprises instructions stored thereon, which when executed by the processor, cause the processor to:
• generate a reference frequency signal comprising a reference waveform;
• generate a frequency-encoded data signal from the detected polarized scattered light;
• synchronize the frequency-encoded data signal with the reference frequency to generate a synchronized frequency-encoded data signal by multiplying the frequency-encoded data signal with the reference waveform;
• and
• determine one or more parameters of the particle based on the synchronized frequency-encoded data signal.