Abstract: A fiber grating that is written into birefringent optical fiber may be placed between two loading plates and bonded in place. The principal polarization axes of the fiber grating written into birefringent optical fiber are approximately 45 degrees relative to the plane of the loading plates and utilizing spacers of a thickness approximately equal to the diameter of the fiber grating written onto birefringent fiber between the plates to measure shear. The principal polarization axes of the fiber grating written onto birefringent optical fiber at approximately 90 degrees relative to the loading plates may be used to measure pressure. When the top and bottom loading plates are of unequal size adhesive and strain relief tubes may be used in conjunction with the loading plates to provide strain relief to the shear and pressure sensors.

Abstract: A fiber grating strain sensor package that is optimized for axial strain sensitivity and usage on a civil structure that may be a bridge or building is described in this invention. Transverse strain effects are minimized and axial strain sensitivity is enhanced through the design of a substrate with an optimized geometry. These sensors have been deployed and tested on a bridge demonstrating very high sensitivity and the ability of this design to be packaged in an environmentally rugged housing necessary for a commercially successful product.