A Method For Determining The Size Of Particles

Abstract: According to the present invention there is provided a method for determining the size of particles, the method comprising the steps of, (a) providing a substrate which has a non-metallic surface having particles on said non-metallic surface; (b) depositing a layer of metal on the non-metallic surface of the substrate and said particles which are on said non-metallic surface of the substrate, so that each of said particles is provided with a respective single layer of metal and an area of the said non-metallic surface which is without particles is provided with a layer of metal, wherein, for each particle there is a gap between the layer of metal on that particle and the layer of metal on said non-metallic surface; (c) illuminating said layers of metal on said particles and said layer of metal on said non-metallic surface of the substrate with electromagnetic rays, so that said electromagnetic rays are scattered by the layers of metal on said particles to produce respectively scattered electromagnetic rays; or illuminating said layers of metal on said particles and said layer of metal on said non-metallic surface of the substrate, so that at least a portion of said electromagnetic rays are absorbed by layers of metal on said particles and another portion of said electromagnetic rays are reflected by said layer of metal on said non-metallic surface of the substrate to produce reflected electromagnetic rays; (d) receiving the scattered electromagnetic rays at an array of photodiodes; or receiving the said reflected electromagnetic rays at an array of photodiodes; (e) forming an image which comprises pixels, wherein each pixel in the image corresponds to a respective photodiode in said array, wherein the colour of each pixel in said image corresponds to the intensity and/or frequency of the electromagnetic rays which photodiode corresponding to that pixel received; (f) processing said formed image to determine the size of the particles.

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