Now the splicer's motors align the cable ends together. Then the fusion splicer generates a small spark at the gap between two electrodes. The reason for doing this is that you need to burn off any moisture or dust which is present. Dust or moisture can cause the splicing process to fail. After this step a much larger spark is generated which raises the temperature at the cable ends above the melting point of glass. This fuses the cable ends together. The location of the spark and the amount of electricity it contains are very carefully controlled. This precise control is necessary in order to ensure that the glass fiber optic splicer and its cladding are not allowed to mix. If they mix together it results in optical loss.
After the cable ends are fused together the fusion splicers injects light through the cladding on one side of the splice and measures the light leaking from the cladding on the other side. This measurement is taken to ascertain the quantity of splice loss. Splice loss is the amount of optical power lost at the splice point as a result of the splicing process. A splice loss of less than 0.1dB is routine when using a fusion splicer.
Generally the fiber ends are inspected before and after the splicing process. This is done using the splicer display screen which provides a magnified view of the splice area.
Fusion splicers are used extensively in the telecommunications industry as well as the computer networking industry. They are a valuable tool for network technicians who maintain fiber networks.