Page 28 - EngineerIt April 2021

How Fujikura developed Arc Fusion Splicing Machines with PAS

In the early days of fibre communication, distance was important and voice communication was the
number one consideration. Today speed plays a pivotal role and fibre is used for voice and Petabytes
of data information, which include audio, broadband internet, video on demand, live streaming
services and many more.
Fujikura Ltd, a Japanese company, was founded in February 1885 by
Zenpachi Fujikura. The company started by manufacturing silk and
cotton insulated winding electrical wires. Since then, Fujikura has
grown to an industrial giant with over 50 000 employees and clocking over USD7 Billion per annum
and has become one of the largest cable manufacturers in the world. Fujikura developed the first arc
fusion splice machine in 1978 and the world’s first core-alignment unit in 1985.
With the advent of optical fibre cables, one of the challenges that presented itself was the joining of
two fibres. The first technology available to join the fibres was mechanical splices, which used a
connecting jelly in a casing; however, these type of connections were not suitable for long distance
transmission.

A new method had to be found to join the fibres in a way that minimized
transmission loss, and to be more permanent and stable. In 1978 Fujikura
developed the first Arc Fusion Splice Machine, the Fujikura FR-1. The unit was
comprised out of an electro-mechanical component and a microscope.

By 1980 Single Mode (SM) fibres were developed and in 1985 Fujikura launched
the world’s first fully automated Arc Fusion Splicing Machine, the F-20 Series. This
was the first splicer to use the Fujikura Profile Alignment System (PAS), now
common in all modern splicing machines. The "FSM-20CS" was recognized
worldwide as being excellent and was put into mass production that moved Fujikura into the no. 1
world market position. Today, 4 decades later, Fujikura still remains the world leader in splice
equipment.
PAS is the intelligent recognition of the core of the fibre. The splicer detects
the refraction of light caused at the core-cladding interface. Images are
taken in two orthogonal planes so that the core can be located precisely.
The unit uses 6 high precision stepping motors to align the fibre on the X-
axis and Y-axis. The camera focus point on the fibre is also adjusted. PAS
information is also used to determine the fibre-type, i.e. SM, MM, DS, NZ
or BIF.

In just microseconds, the splicer reads the cleave angle at the edges of the fibre and checks for foreign
anomalies like dust or moisture and does a cleaning arc to remove any. The final splice-arc is at DC
8000 Volts across two electrodes and is carefully controlled by a very sophisticated (secret) algorithm
which sets the arc frequency, arc power and duration. Stepping motors move the fibre in whilst the
unit arcs and a perfect joint is achieved.
Environmental information, i.e. temperature, humidity and altitude is used before and during the
splice arc to automatically adjust the algorithm. Any adjustments are stored and used for the next arc.
This keeps the Fujikura splicer accurate even if environmental changes occur.

EngineerIT | April 2021 | 26