Fluid-borne particle detector

An apparatus for detection of a fluid borne particle and for measuring the particle size, comprising:

• i. a pair of coaxially opposed concave reflective surfaces separated by three times focal length of the concave reflective surfaces about a zone whereby flow means are provided for delivering a fluid flow comprising the fluid borne particle through the zone;
• ii. a laser arranged to illuminate the fluid flow in the zone;
• iii. a first and second detector wherein the first detector is arranged to detect scattered and/or emitted light of a first wavelength band emanating from the zone, the second detector is arranged to detect scattered and/or emitted light of a second wavelength band emanating from the zone and the second detector is capable of detecting back or side scattered light;
• iv. a first and second light source wherein the first source is arranged to illuminate the zone with light of a third wavelength band and the second source is arranged to illuminate the zone with light of a fourth wavelength band;
• and
• v. a third detector arranged to detect forward scattered light as a result of illuminating the particle by the laser and/or the first or second light source to provide an assessment or identification of particle shape
• whereby the laser and the first and second light source are each arranged in a plane substantially orthogonal to the direction of the fluid flow provided for by the flow means, the second detector and the third detector are capable of recording size measurement through light scattering, and
• the apparatus further comprises a feedback system between the second detector and the third detector that combines output from the second and third detector to reduce the effect of Mie oscillations in a sizing response curve in order to provide accurate measurement and identification of a single particle size.