Fabrication Procedure of Thin Sections for Polarizing Microscopes
Preparation Process of Thin Sections for Polarizing Microscopes
When observing under a polarizing microscope, specimens need to be made into qualified thin sections or polished sections, collectively referred to as thin sections. The preparation procedure is as follows:
(1) Sampling: Select representative areas of the sample according to observation and analysis requirements, cut them into 10×10×10 mm cubes, and clean thoroughly.
(2) Mounting or potting: Small-sized samples require mounting. Samples with porous or loose structures shall be impregnated first.
(3) Rough grinding: Place the flatter side of the sample on a grinding machine, grind the surface with coarse abrasive powder to trim the profile and remove sharp edges and corners.
(4) Fine grinding: Grind with fine abrasive powder until all marks left by rough grinding are eliminated.
(5) Pre-polishing: Use finer abrasive powder for grinding until the surface becomes flat. Faint light reflection can be observed on the surface under bright light.
(6) Polishing: Place the specimen on a polishing machine, add polishing compound (polishing powder) for polishing until the specimen surface
is bright and no obvious scratches are visible under a reflected-light microscope.
(7) Labeling: Number the ground specimens and attach labels to specify their source and name.
(8) Etching: Select appropriate etching methods and conditions to etch the specimen according to observation and analysis requirements.
If microstructural analysis needs to be performed under both transmitted and reflected light, the specimen shall be fabricated into a thin section or even an ultra-thin section (<0.02 mm). For thin section preparation, first grind the specimen into a 0.03 mm-thick slice without covering it with a coverslip. Then polish the pre-ground slice surface on a polishing machine to complete the thin section.
