How to Monitor the Optical Fiber Splicing Quality?

For optical fiber cable splicing quality monitoring, at present in the engineering mainly have three kinds of monitoring methods，

First, using the display screen of the welding machine to monitor

Second, using OTDR to monitor the splicing point

Third, using light source, optical power meter to weld loss to cut or insert test, but direct cut or insert belong to destructive testing, so it is not usually using in engineering.