The principle of optical fiber fusion machine is that when parallel light is illuminated from the side to the optical fiber, the light and dark images between the core and cladding and between the cladding and air can be observed due to the refraction of the optical fiber. The horizontal and vertical images of the optical fiber can be observed by the moving microscope. The analog video signal is obtained by focusing the objective lens on the charge coupler, and then converted into digital signal by analog/digital conversion circuit. The image is processed and recognized by the microprocessor in the welder, so that the alignment of the core and cladding can be visually displayed.

Electrode pre-discharge cleans the end face of optical fibers. Electrode discharge melts the end face of docking optical fibers, and makes use of the force of quartz molecules to connect optical fibers. The working principle diagram is as follows:

There are three main principles for the splicing of optical fiber fusion machine: the basic principle of welding, the alignment principle (PAS system), and the principle of estimating loss.

1. Basic Principles of Splicing

The fusion principle of the optical fiber fusion machine is relatively simple. First, the optical fiber fusion machine should find the core of the optical fiber correctly and align it accurately. Then, the optical fiber can be melted by the high voltage discharge arc between the electrodes and then fused. As shown in the figure:

2. Alignment Principle (PAS System)

As shown above, the big circle is the optical fiber cladding and the small circle is the optical fiber core; f is the focal point of the optical fiber cladding, F'is the focal point of the core; and L is the focal length of the objective lens.

3. Principle of Estimating Loss

The estimation of the welding loss of the optical fiber fusion machine is based on the factors such as the dislocation, deformation of the core joint and whether there are bubbles or not. The real loss is not measured by light source, optical power meter or OTDR.