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The Automatic Filter Analysis System of JOMESA:
Cleanliness Analysis, Measurement Process, The patented Metal-Nonmetal recognition, Evaluation Samples, Oil Cleanliness

JOMESA HFD: Metal-Nonmetal Recognition

Metallic particles:









When analyzing the residue particles on a filtermembrane, the detection of metallic particles is of outstanding importance.
JOMESA recognized very early (2006) the significance of metal detection and developed a system based on polarized light, which was quickly accepted as a patent

It starts with the illumination of the sample: JOMESA uses polarized light to illuminate the filter.

LED ringlight

LED ringlight with linear polarization attached

Ringlight, polarization with driving belt







Usual light sources emit non polarized light. The light contains all oscillation directions.

By passing through a linear polarizing foil the light has one (linear) osciallation direction.

JOMESA automated polarization system

The human eye is incapable of recognizing polarization.
Samples illuminated with polarized and unpolarized light look the same.


The way how metal and nonmetal particle scatter polarized light is the key of metal-nonmetal detection





Metal surfaces reflect the incident light, like mirrors. Incident and reflected light have the same oscillation direction.

Nonmetal substances modify or disturb the incident light direction (mostly because light can intrude into the material),
Light scattered from nonmetal particles is no more polarized.

What happens if the scattered light enters a second polarization device ?







Polarized light can go through polarizers which have the same direction.

When polarized light and grate have orthogonal orientation, light cannot pass the polarizer.

Unpolarized light can pass any polarizer (with diminshed intensity)


JOMESA has harnessed this physical effect in an automated system since 2006.
Pictures of the particles, illuminated with polarized light, recorded in two polarization situations are compared and then
used to discriminate between metallic and nonmetallic particles.

















Metal with parallel polarizer

Metal with orthogonal polarizer

Nonmetal with parallel polarizer

Nonmetal with orthogonal polarizer

Comparison of images (parallel polarisator position versus orthogonal polarizer postion):
Reflexion in orthogonal polarizer position gets black ---------------------> It is a metal.
Reflexion in orthogonal polarizer position gets some sort of grey ---> It is a nonmetal

Now that we have all essential information (particle sizes, metal-nonmetal) collected from the particles on the filter membrane,
we printout the results: Evaluation