Polarization-Maintaining Fiber Collimator is assembled precisely by PM fiber pigtail and a focus lens, which can convert the divergent light into a parallel beam (Gaussian beam) from fiber export , or couple space parallel light into the fiber. It can be used singly to achieve a specified beam size at the required position, or paired with other optical components such as filters and isolators in between two collimators to meetspecific customer needs.                                                                                                                                                                          In fiber optic interferometric sensors based on optical coherence detection, the use of polarization-maintaining fibers can ensure the unchanged polarization direction, improve the coherence signal-to-noise ratio, and achieve high-precision measurement of physical quantities.