Abstract: A method for determining a characteristic of particles in a fluid sample and/or a contamination characteristic of the fluid sample includes: (a) depositing a metallic film on a surface of a substrate; (b) bringing the fluid sample into contact with the metallic surface; (c) removing the fluid sample from the metallic surface; (d) depositing a layer of metal on the metallic surface and the particles which remained on the metallic surface; (e) illuminating the layers of metal on the particles and metallic surface with electromagnetic rays; or illuminating the layers of metal with electromagnetic rays; (f) receiving the scattered electromagnetic rays at an array of photodiodes; or receiving the reflected electromagnetic rays at an array of photodiodes; (g) forming an image which includes pixels; and (h) processing the formed image to determine a characteristic of the particles and/or a contamination characteristic of the fluid sample.