How to control optical fiber polishing with the help of microscope

Polishing of the edges of the optical connector ferrules determines in many respects the quality of the optical connection. That's why, it is very important to examine the quality of polishing by means of a microscope. Check for microscratches and the glue residues on the ferrule and fiber. Fiber shift, deep shearing or, vice versa, the insufficiently processed edge may be observed. If polishing is performed well, a uniformly dark (or uniformly light) inner circle may be seen in the microscope.

Good quality of polishing

Satisfactory quality of polishing
Glue residues and dirt may be seen		Glue residues may be seen; the fiber core is inconsiderably damaged
Inadequate quality of polishing
Alcohol stains may be seen clearly		The fiber is shifted to the edge of the glue channel (glue crescent from the left)
Numerous scratches resulting from overpolishing using coarse polishing paper	A shearing at the fiber core
Dirt may be seen	Excess adhesive, scratches