Fusion-splicing polarization maintaining optical fibers includes the steps of: observing a polarization maintaining optical fiber containing stress applying members in a predetermined direction, using a core direct monitoring method to obtain a reference image; aligning the pair. Fusion-splicing polarization maintaining optical fibers includes the steps of: observing a polarization maintaining optical fiber containing stress applying members in a predetermined direction, using a core direct monitoring method to obtain a reference image; aligning the pair. The TUNE PM 500 Splicer is an innovative device designed for fusion splicing polarization-maintaining (PM) fibers., temperature, stress, magnetic fields). Precise alignment (especially polarization axis matching) by fusion splicers minimizes polarization crosstalk at splice points. As a high-precision optical fiber processing equipment, the polarization-maintaining fiber fusion splicer plays a key role in the application of optical gyroscopes, fiber hydrophones, fiber fan-in and fan-out devices, and fiber couplers. The following is an overview of its specific application. Polarization-Maintaining Fiber (PM Fiber) plays a vital role in various applications that require optimal signal integrity and polarization stability, such as telecommunications, fiber optic sensing, and laser systems. With this technique, the most common types of PM fibers can be precision aligned even elliptical core, without end launch or.