光纖光柵壓力計之研發

Abstract

本研究主要目的是研發使用光纖光柵做壓力感測器並應用於地下水壓之監測技術，使其成為兼具解析度與穩定度的監測系統。 地層中水壓的量測為監測系統中，極為重要的一項數據，水壓力的改變往往可作為地層變化的重要依據。但在深層土壤中使用傳統電子式水壓計有其困難性及高成本，這都會影響到量測的品質。光纖光柵感測器，具有體積小、不受電磁波幹擾、可長距離傳輸訊號與可分佈式之優點。本研究所研發之光柵壓力感測器有兩種，分別為漸變式光柵壓力感測器與拉伸式光柵壓力感測器，漸變式感測器具有多功的特性；拉伸式感測器，具有構造簡單和體積小的優點，較不受空間限制的特性。 本論文包括以上兩種光柵壓力感測器之設計原理，並以彈性力學為理論探討感測器量測上的效能，與感測器之室內標定檢驗並與理論相比較。

The objective of this research is to develop an optic fiber Bragg grating (FBG) pressure sensor that can be applied in the field for ground water monitoring. The sensor should have the resolution and stability required for the field applications. Water pressure/level can be an important part of the field monitoring system for purposes such as ground subsidence and slope stability. The use of conventional electronic pressure sensors can have drawbacks that relate to electronic devices. If properly designed, FBG sensors have the advantages of small size, light weight and immune to electromagnetic interference. This research develops two types of FBG pressure sensors. The first type modulates the pressure by chirping of FBG (the chirp sensor). The other design is based on uniform stretching of FBG (the stretch sensor). The chirp sensor has the potential of multi-purpose as it can be used a load cell or displacement sensor. The stretch sensor is compact. The thesis describes the design principles of the two FBG pressure sensors, predict the performance of the sensors based on linear elastic analysis of the sensor components. The developed sensors were tested in the laboratory, and the results were compared with the linear elastic analysis.