Modern Particle Characterisation under the Microscope

The microscope retains a vital and wide-ranging role in modern industrial processes.

For instance, the pressure to optimise the quality of cast components requires a means of examining large, polished sections for defects both large and small whilst the identification of wear particles in lubricated systems is commonplace for many manufacturing companies. At the same time, continuing miniaturisation, higher packing densities and ever more rigorous quality assurance means that the physical size of particles capable of adversely affecting industrial processing and product quality is diminishing rapidly and making their characterisation more difficult.

And, many manufacturers need to microscopically examine their finished product to verify the absence of contaminating particles of all sizes, particularly in foodstuffs and pharmaceuticals. Indeed, many sectors, including pharmaceuticals and the automotive supply industry, need to document their complicity with guidelines and standards, such as CFR 21 part 11 and ISO 16232.

Miniaturisation and increasingly rigorous quality standards mandate the use of analysis systems able to rapidly detect, measure and categorise increasingly small particles, of the order of a few micrometers, whilst still being able to cope with large particles or fragments. However, the data volumes involved in acquiring high-resolution images of these increasingly small particles within a large and heterogeneous sample field overwhelms the available memory in even high-specification computers and workstations.

Until now, the only answer has been to measure twice – at high resolution for small particles and, separately, at lower resolution for larger particles. A fast and accurate method to characterise the whole population of particles and their possible origins would bolster product confidence and boost company revenues, through decreased production downtime and quality assurance man-hours.

PARTICLE ANALYSER Particle Analyser images complete samples in a single step, using either the SteREO Discovery range of stereomicroscopes (Carl Zeiss) for particles larger than 25 microns or the Axio Imager range of upright microscopes (Carl Zeiss) for particles down to 2.5 microns (Figure 1). The system measures whole heterogeneous populations of particles to allow automatic classification of particle types, and deliver fully resolved images on demand.