Method for dosing a biological or chemical sample

A method of assaying a biological or chemical sample, which comprises:

• placing said sample in a chamber having transparent sides;
• illuminating the sample using a light beam coming from a source;
• producing an image of the light beam diffused by the sample, wherein said image comprises an illuminated volume zone, a light beam point of entry zone, a light beam point of exit zone, a meniscus zone, and an artefact zone;
• recording the spatial structure of the image;
• examining the spatial structure of the image and distribution of light energy in the image with respect to one or more references, measuring noise created by the step of illuminating the sample, and defining one or more regions of interest so that measuring information can be extracted;
• extracting the measuring information, wherein the extracted information is specific to the interaction of the light beam with the sample;
• recording the measuring information;
• and
• calculating the assay with respect to the measuring information.