POLARIZED-LIGHT MICROSCOPY AS A FILTER DEBRIS ANALYSIS TOOL

The use of polarized light microscopy (PLM) as an analysis tool for lu be oil filter debris examination is investigated. Reflectance PLM is s hown to be able to discriminate between metallic wear particles and no nmetallic particles present in filter debris by differentiating optica lly isotropic vs. anisotropic materials. The utility of transmittance PLM in identifying common nonmetallic materials in filter debris is al so demonstrated The identification is accomplished by estimation of th e particle's refractive indices through a technique known as dispersio n staining. That information, coupled with knowledge of the material's morphology, permits identification by comparison with literature refe rences.