Fiber fusion splicer is used for the construction and maintenance of optical cables in optical communication. The principle of fiber fusion splicer is relatively simple. First, the fiber fusion splicer must correctly find the core of the optical fiber and align it accurately, and then melt the optical fiber through the high-voltage discharge arc between the electrodes and then promote the fusion.
Working principle of fiber fusion splicer
When parallel light is irradiated on the optical fiber from the side, due to the refraction of the optical fiber, the light and dark images between the core and the cladding and the cladding and the air can be observed. The horizontal and vertical images of the optical fiber can be observed by moving the microscope. It is focused on the charge coupler through the objective lens to obtain an analog video signal, which is then converted into a digital signal through the analog/digital conversion circuit. The image is processed and identified by the microprocessor in the fiber fusion splicer, so that the alignment of the core and the cladding can be intuitively displayed. The electrode pre-discharge cleans the end face of the optical fiber, the electrode discharge melts the end face of the butt optical fiber, and the force between the quartz molecules is used to connect the optical fibers.
The fiber fusion splicer mainly follows three principles for fusion: the basic principle of fusion, the alignment principle (PAS system), and the loss estimation principle.
1. Basic principle of fusion splicing
The principle of fusion splicing of optical fiber fusion splicer is relatively simple. First, the optical fiber fusion splicer must correctly find the core of the optical fiber and align it accurately, and then melt the optical fiber through the high-voltage discharge arc between the electrodes and then promote the fusion splicing.
2. Alignment principle (PAS system)
The large circle is the optical fiber cladding, and the small circle is the optical fiber core; the straight line formed by the focus of the optical fiber cladding and the focus of the core is the focal length of the objective lens.
3. Principle of estimated loss
The estimation of the fusion loss of the optical fiber fusion splicer is calculated based on the misalignment, deformation, and whether there are bubbles of the fiber core joint. The real loss is not measured by special optical meters such as light source, optical power meter or OTDR.
Structure of optical fiber fusion splicer
The optical fiber fusion splicer uses arc discharge to generate a high temperature of more than 2000℃ to fuse two optical fibers into one optical fiber. A high-performance optical fiber fusion splicer must be configured for optical fiber fusion splicing projects. However, the structure of the optical fiber fusion splicer consists of the following parts.
Fiber fusion splicer display screen:
Fiber fusion splicer uses infrared light source and display screen to observe the entire fiber fusion process, and the magnification of fiber can reach 200-300 times. In the past, many domestic brands of machines changed the focal length to observe the X and Y directions of the fiber respectively, and the fusion speed was very slow. Now the fiber fusion splicer generally uses the fiber core direct viewing method (PAS) to monitor the alignment. The LCD display can simultaneously display the fiber fusion process in the X and Y directions to observe the fiber status and fusion quality, and the fusion speed is fast.
Fiber fusion splicer controller:
Fiber fusion splicer controllers usually include two parts: monitoring unit and microprocessor. The monitoring unit is the monitoring of local optical power, and the microprocessor completes automatic adjustment and connection loss estimation. The discharge time and discharge current of the starting end can be adjusted by changing the microcomputer program. The third-generation machine uses a high-resolution camera to observe the fiber vertically, and then displays the fiber image on the fluorescent screen, and uses the lens effect of the fiber cladding to directly display the alignment of the connected fiber core. At the same time, the camera provides this observation information to the ZX microprocessor controller, which controls the fine-tuning mechanism for automatic alignment, and controls the indirect estimation of discharge and fiber connection loss.
High-voltage source of the heating furnace of the optical fiber fusion splicer:
There are two main types of high-voltage sources. One is to boost the 50Hz, 220V AC to 3000-4000V and the current is about 20mA; the other is a 20kHz or 40kHz high-frequency power supply. The high-frequency high-voltage source has the characteristics of small transformer size, high efficiency, and integrated circuits, so it is used most in actual engineering practice.
Discharge electrode of optical fiber fusion splicer:
A pair of electrodes processed from tungsten rods into a 300 cone shape are installed on the electrode rack of the optical fiber fusion splicer, and the electrode spacing is generally 0.7mm. When the optical fiber is connected, the discharge of the electrode generates an arc between the electrodes, and the instantaneous temperature reaches about 2000℃, so that the optical fiber at the ZX position of the arc melts. After the electrode has been used for a period of time, there will be an oxide adhesion layer on the surface, and the electrode should be cleaned regularly. The discharge life of common electrodes is 2000 times. If the electrodes are used continuously after excessive consumption, the quality of fiber splicing will be affected.
Core adjustment frame of optical fiber fusion splicer:
Core adjustment device of optical fiber fusion splicer is also called debugging frame, which usually uses "lever" type fine adjustment mechanism. The three-dimensional fine adjustment of V-groove is achieved by screw micrometer installed at the end of long rod. The optical fiber placed in the V-groove is fixed by mechanical pressure plate. X and Y direction fine adjustment is driven by servo motor, and the lever mechanism is to make the adjustment more precise. Axial (Z direction) adjustment is moved by screw micrometer.