Characteristics Measurement and Jitter-Reduction of MEMS Scanning Mirror System

微機電製品有著輕巧、微小、堅固與快速的切換時間(通常指共振頻率)，透過光學知識與微機電技術融合，一種新的領域微光機電系統因應而生。在眾多光學元件中，微機電掃瞄面鏡藉由隨時間變化的轉動角度，使得入射到微機電掃瞄面鏡上的光線，被反射到各種不同的角度上。由於微機電掃瞄面鏡可以忽視光波長的影響，而達到高解析度和大轉動角度的特點，使得它被廣泛應用在商品、科學與工業應用上。 本論文所使用的微機電掃描面鏡為設計來取代現有雷射印表機所使用的多面鏡。由於微機電掃描面鏡在掃描過程中，因輸入訊號、系統本身及製造過程因素，會產生抖動的現象。鏡面的優劣主要決定於抖動量的多寡，如何量測鏡面的特性及有效地降低抖動的產生成為重要的研究議題。一般微鏡面的設計，須經由成品的製作，藉由實際量測數據再來修正原有設計，往往需重覆修改數次設計才能達到系統要求。本論文主要在於建立自動化量測平台，分析鏡面的動態特性。經由量測資訊來進一步設計回授控制來達成抖動量的降低。論文主要分兩部分，第一部分為量測系統的建立，量測微機電掃描面鏡的動態特性。第二部分為回授控制的設計，藉由回授控制的設計來達成抖動量的降低。實驗中，利用回授控制的方法，經由電腦擷取分析感測器輸出訊號，來控制輸入驅動訊號有效達成減少抖動量降低，並使得微機電掃描面鏡的抖動量穩定在固定範圍。Micro-Electro-Mechanical System (MEMS) has the properties of light, small, strong and fast response time. A new research territory of MOEMS is formed by the combination of optical and MEMS technology. Among these optical components, MEMS scanning mirror can be used to reflect the incident light to different angle by the time-variant rotating. Because MEMS scanning mirror provides the high resolution and large scanning angle without the limitation of wavelength, it is widely used in different application of industrial and science. The MEMS scanning mirror used in this thesis is designed to replace the polygon mirror which is commonly used in the laser printer. Because of the variation of input signal and the defect of manufacture, the MEMS scanning mirror has the problem of Jitter which is defined as the speed fluctuation. The property of MEMS scanning mirror is defined by the amount of Jitter. How to measurement the property of MEMS scanning mirror and how to reduce the Jitter become important issues. The existing method of jitter-reduction is to re-design the system. In order to achieve the requirement of specification, the design should be changed repeatedly. It costs lots time and money for manufacture. In this thesis, the measurement system is set up and the feedback control for jitter-reduction is proposed. There are two parts in the thesis. The first part is the set up of measurement system which provides automatically acquirement of the dynamic characteristic of MEMS scanning mirror. The second part is the design of feedback control for jitter-reduction. The design of feedback control provides the reduction of Jitter and stabilization of Jitter in certain range.Abstract i 摘要 ii List of Figures v List of Tables viii Chapter 1 Introduction 1 1.1 Motivation 4 1.2 Overview and Organization 5 Chapter 2 Dynamic Characteristics of MEMS Scanning Mirror 7 2.1 Mirror Dynamics 7 2.2 Performance factor of MEMS scanning mirror 12 2.3 Review on the Characteristics Measurement and control scheme of MEMS scanning mirror 14 2.3.1 Review on Characteristics measurement of MEMS mirror 15 2.3.2 Review on Control of MEMS mirror 21 Chapter 3 Characteristics Measurement of MEMS Scanning Mirror 25 3.1. Experimental Setup 25 3.1.1. Sketch of the experimental setup 26 3.1.2. Hardware Configuration 29 3.1.3. Alignment Procedure 34 3.2. Measurement Design 36 3.2.1. The Flowchart of Measurement 36 3.2.2. The Interface of Measurement 40 Chapter 4 Jitter-reduction of MEMS Scanning Mirror by Feedback Control 43 4.1 Experiment Setup 43 4.2 The Flowchart of Control Scheme 44 4.3 The Interface of Control Scheme 49 Chapter 5 Experiment Result 51 5.1 Variation of input signal 51 5.2 Measurement result of dynamic characteristics 55 5.3 The performance of Jitter-reduction by feedback control 56 Chapter 6 Conclusion 60 References 6