Design of a beam condense system with simple structure

In order to detect weak magnetic field, the demonstration based on all-fiber full polarization Sagnac magnetic sensor was used in our scheme. Beam condense system(BCS) is very meaningful as one of the key technologies in this magnetic sensor. In the paper, we introduce a simple way to design a BCS. Because of the restriction of the system space, the BCS can't take too much space. However, the common product of beam condense system is kind of complex and will take much space, these disadvantages can't meet the application. We choose small lenses, design the simple workpiece by ourselves and coupling into our detection system. The workpiece including pressure rings and sleeves. In our plan, we choose telescope system as optical path. After passing the beam condense system, the diameter of beam can be smaller and reflect in magnetic-optical crystal (MOC) many times. In this way, the sensitivity of detection system can be magnified for about 11 times. Overall, the most obvious advantages of this beam condense system are simple structure, small space and low cost. There are two important parameters of beam condense system: The first is called condense ratio, which can be controlled by the choice of lenses. The second is called final beam diffusion angle, which depended on both the condense ratio and beam diffusion angle of collimating lens.