Analysis of Misalignment Sensitivity of a Hi-Bi Fiber-Based Interferometric Displacement Sensor
The use of birefringent (Hi-Bi) optical fibers makes it possible to implement interferometric displacement sensors which are miniaturized, flexible, and accurate over an extended measuring range. With respect to ordinary interferometric systems based on free propagation of light, these sensors provide a higher geometrical flexibility, which is particularly appealing with reconfigurable measuring machines. As recently presented1, it is possible to keep the laser source and the photodetectors remote from the measuring head using a HiBi optical fiber. Theoretically, the approach presented has proven to be insensitive to fiber bending and to fiber temperature changes. In fact, HiBi fibers provide adequate control of the polarization state of the beams, if the input polarization state is correctly adjusted with respect to the orientation of the fiber polarization axes. However, residual angular misalignment of the fiber ends due to the complex procedure needed to identify the fiber optical axis2,3, and a non perfect polarization separation of the laser beam may result in a sensitivity of the measuring system to fiber perturbations. The sensitivity to such misalignments must therefore be taken into account for high precision measurements: in this work an analysis of the residual sensitivity to fiber thermal and mechanical stresses due to angular misalignment fiber end is presented.
KeywordsDrawing Plane Angular Misalignment Grin Lens Interferometric Signal Input Polarization State
Unable to display preview. Download preview PDF.