Illuminate with a laser light source. The other end of that optical fib is tested by an optical pow meter, and the attenuation of the broken optical fiber is tested accord to the luminous intensity of the light source and the intensity of the light source received by the optical power meter.

Generally, the quality of optical fiber fusion is judged by fusion loss and fusion point strength, and the core evaluation criterion is fusion loss.

"Polishing" with OTDR equipment is generally used for long-distance optical fiber testing. One end of the optical fiber is connected with the equipment that emits optical signals. The equipment detects the optical signals reflected by different attenuation points and breakpoints in the optical fiber, and calculates the actual length of the point from the test point. Therefore, the position of optical fiber breakpoint or poor fusion can be quickly judged.