Method, system and apparatus for monitoring variations in the size of particles present in a fluid

A method of detecting an onset of a variation in particle size in a fluid, the method comprising:

• splitting an optical signal of a predetermined wavelength from an optical source onto first and second optical paths, wherein the first optical path does not pass through the fluid and the second optical path passes through the fluid;
• monitoring the first optical path for optical source drift;
• measuring intensity attenuation with an optical detector at the predetermined wavelength by the fluid with respect to time, wherein the intensity attenuation is observed substantially along an axis of the second optical path;
• adjusting the measured intensity attenuation to reflect the optical source drift;
• determining a rate of change of intensity attenuation from the adjusted sampling data;
• and
• detecting the onset of the variation in particle size by detecting whether the rate of change of the intensity attenuation has passed a threshold rate of change.