單秋成臺灣大學：機械工程學研究所林志郎Lin, Chih-LangChih-LangLin2007-11-282018-06-282007-11-282018-06-282004http://ntur.lib.ntu.edu.tw//handle/246246/61401本論文包含兩個主題：光纖布拉格光柵(FBG)感測器和雷射趨動式高分子微感測器.在第一部份中，主要提出分析一個作用於非均佈應變場的FBG反射頻譜的架構，和量測微裂縫尖端應變的實驗結果，並且檢驗FBG 的gauge length在量測應用上的影響，本實驗的結果可用來做為推斷或分析非均佈應變場的參考資訊。第二部份乃是研究雷射趨動式高分子感測器在黏度計，流速計和微幫浦等之應用。這些感射器是以低成本的雙光子吸收高分子化技術快速地製成，可自由地在液體中游動，而以線性極化雷射光鉗抓取和控制，在雷射焦聚處產生光扭矩，得以藉此方式測量該處之流體特性。黏性和流速感測器具平板形狀並都會依極化方向排列。其中，黏性的量測可藉由轉動線性極化方向所產生的最大旋轉頻率得到，而液體流速則是藉由量測光扭矩和拖曳扭矩的平衡角度所得，這些實驗結果與理論計算所得非常吻合。最後，微幫浦具阿基米得螺旋形狀的微尺寸，當其被雷射抓取於焦聚時會依其長軸方向旋轉，此旋轉的原理是由於雷射光射散到螺旋上所轉換成的光扭矩所造成。This work involves two topics which are fiber Bragg grating (FBG) sensors and laser driven microsensors. In the first part, a framework for the interpretation of reflected FBG spectra under a non-uniform strain field is proposed and experimental results for a crack tip strain field are presented. The effect of FBG gauge lengths on the measurements is examined and interpreted. The results are analyzed to see what information can be derived and how accurate the interpreted strain results are. In the second part, the fabrication of laser driven polymer microsensors for viscosimetry, velocimetry and micropump applications is considered. These sensors are readily made with a low-cost polymerization technique based on two-photon absorption. A linearly polarized optical tweezers is used to trap one sensor, freely floating in the liquid to be characterized, at the laser focal point and to generate the optical torque needed for local hydrodynamic measurements. Viscosity and velocity microsensors have slab shapes that align in the polarization direction. The local viscosity is deduced from the maximum rotation frequency generated by the rotating linear polarization, while the fluid velocity is obtained by measuring the maximum angle that equilibrates the optical and drag torques. The experimental results are in good agreement with the theoretical calculations. Micropumps are micron-size Archimedes screws that rotate around their long axis when trapped at the focal point. The rotation is due to the optical torque that is transferred by the laser scattering on the screw.Outline Part 1 Fiber Bragg grating sensors 1 I. Fundamentals of fiber Bragg grating sensors 3 1. Introduction to fiber Bragg grating sensors..…. 4 1.1 Fiber Bragg gratings (FBGs) .................... 4 1.1.1 Optical fibers ................................. 4 1.1.2 Principle of FBGs .............................. 6 1.2 Principle of fiber Bragg grating sensors ....... 8 1.2.1 Uniform strain applications .................... 8 1.2.2 Non-uniform strain applications ............... 11 2. State of the applications of FBG sensors....... 14 2.1 Smart structure applications ................... 14 2.2 Structure damage monitoring ..................... 16 2.3 Composite fabrication process monitoring …..…………………….17 2.4 The objectives of this thesis …………………………………... 18 II. Applications of FBG sensors 23 1. Fabrication of FBG sensors ……………………………………..… 24 1.1 Introduction to the fabrication of FBGs …………………….…….…. 24 1.2 Our FBGs ………………………………………………………….… 25 1.2.1 Materials and experimental setup …………………………….… 25 1.2.2 Fabrication procedures ……………………………………….… 26 2. Fundamental tests for FBG sensors ……………………………………... 27 2.1 Mechanical tests …………………………………………………….. 27 2.1.1 Mechanical properties of our optical fiber ……………………... 27 2.1.2 The effect of embedded optical fibers for laminated composites. 29 2.2 Calibration of FBG sensors ……………………………………. 30 2.2.1 Strain (Kε) and temperature (KT) coefficients ………………….. 30 2.2.2 Feasibility tests for the embedded FBG sensor …………………. 32 3. The feasibility studies of FBG sensor applications ……………………… 35 3.1 Dynamic strain measurement ………………………………………...… 35 3.1.1 Experiments ………..……………………………………………. 35 3.1.2 Results and discussion …..………………………………………. 35 3.2 Manufacture process monitoring ……………………………………….. 36 3.2.1 Experiments ………………..……………………………………. 36 3.2.2 Results and discussion …………..………………………………. 37 3.3 Holed specimen monitoring …………………………………………..... 40 3.3.1 Experiments ………………………………..……………………. 40 3.3.2 Results and discussion ………..…………………………………. 41 3.4 Monitoring of strain field induced by crack tips ……………………….. 43 3.4.1 Experiments …..……………………………………………...….. 43 3.4.2 Results and discussion ………………………………………....... 44 Part 2 Laser-driven polymer micro-sensors 51 I. Background of optical laser tweezers 53 1. Introduction to optical tweezers …………………….………………..… 54 1.1 History of optical tweezers ……………………………………………... 54 1.2 Principle of optical tweezers …………………………………………… 55 1.2.1 Ray optics model …………………………………………….…. 56 1.2.2 Electromagnetic model ………………………………………..... 60 2. Laser driven micro-rotors …………......………………………………... 63 2.1 State of the art ………………………………………………………….. 63 2.2 Our objectives ………………………………………………………….. 70 II. 3D micro-fabrication by two-photon initiated polymerization 73 1. Principle of two photon initiated polymerization ………...…………... 74 1.1 Principle of two-photon absorption (TPA) microfabrication ………...… 74 1.1.1 Photopolymerization …………………………………………… 74 1.1.2 Two-photon absorption …………………………………………. 75 1.1.3 Spatial resolution ……………………………………………….. 75 1.1.4 Process of TPA microfabrication ……………………………….. 76 1.2 State of the art ………………………………………………………...… 77 2. TPA 3D microfabrication ……………………………………………….. 82 2.1 Our TPA resin ………………………………………………………...… 82 2.2 Sample preparation ……………………………………………………... 82 2.3 Experimental setup ……………………………………………………... 83 2.4 Demonstration of TPA fabrication ……………………………………… 85 2.4.1 Optimization of experimental parameters …………………….…... 85 2.4.2 3D structure demonstration ………………………………….……. 87 III. Rotational properties of laser driven microstructures 91 1. Principle of laser driven microstructures …………………………...…. 92 1.1 Optical torque ……………………………………………………… 92 1.2 Equation of motion ........................................................................... 96 2. Experimental procedures …………………………………………….... 100 2.1 Experimental setup …………………………………………………. 100 2.2 Sample preparation ………..………………………………………... 101 2.3 Laser manipulation and measurements ……..…………………….... 101 3. Results and discussion ………………………………………………….. 103 3.1 Observation of slab rotation …………………………………………. 103 3.2 Quantitative study of rotation ……………………………………….. 104 3.2.1 Linear relationship of rotational frequency and optical power .. 104 3.2.2 Measurement of phase delay ………………………………….. 106 3.2.3 Critical conditions for rotation ………………………………… 105 4. Summary …………………………………………………………………. 109 IV. Applications of laser driven microstructures 111 1. Micro-viscosimeter …………………………………………………..… 112 1.1 Principle of micro-viscosimeter …………………………………...… 112 1.1.1 Rotation characteristics ………………………………………. 112 1.1.2 Equation of motion …………………………………………… 113 1.1.3 Viscosity measurements …………………………………… 114 1.2 Experimental results and discussion ………………………………… 114 2. Micro-velocimeter ……………………………………………………. 118 2.1 Flag-shaped microsensor ………………………………………… 118 2.2 Principle of measurement ……………………………………………. 119 2.3 Experimental validation …………………………………………. 122 3. Micro-pumps ………………………………………………………….. 123 3.1 Principle of the photon-driven micro-pump ………………………. 123 3.2 Micropump fabrication …………………………………………….… 124 3.3 Experiments ………………………………………………………….. 126 3.3.1 Rotation observation …………………………………………. 126 3.3.2 Experimental validation ……………………………………… 127 3.3.3 Horizontal pump application ………………………………… 128 4. Summary ……………………………………………………………… 130 Conclusion 133en-US阿基米德螺旋非均佈應變場微幫浦光鉗高分子雙光子吸收FBG感測器光譜微黏度計高分子化微感測器光纖布拉格光柵micropumpnon-uniform strain fieldpolymermicrosensorspectrumFBG sensormicro-velocimetrytwo-photon absorptionpolymerizationmicro-viscosimetryArchimedes screwfiber Bragg gratingsoptical tweezersthesis