5. Sample preparation

5.1 Consideration of the number of particles to be counted

As with all direct measurement techniques, the particles imaged and measured represent only a tiny fraction of the population studied. It is therefore essential to question the representativeness of the population actually measured. Obviously, the greater the number of particles imaged, the more representative the population will be of the sample. However, for practical reasons, the number of particles imaged must remain limited, as measuring several thousand particles requires images to be taken over long periods of time. Consequently, it is necessary to determine the error associated with the limited number of particles measured.

The latter has been evaluated in several works