- 學位論文
像素射線法之應用研究：光場相機、共軛焦顯微鏡、波前感測器的共通技術平台
Applied Research on Pixel Ray Method: Common Technology Platform of Light Field Camera, Confocal Microscope, Wavefront Sensor
摘要
像素射線可被用來描述光線在空間中的傳遞方式。因此，取得像素射線資訊，再透過適當的分析，就可用以建構可對不同物理參數進行檢測的各種量測系統。運用像素射線來建構此類量測系統正是本論文的研究主軸。 Shack-Hartmann波前感測器是一種能夠取得像素射線資料的儀器，因此，本研究首先改良Shack-Hartmann波前感測器，由於微透鏡結構受到光學透鏡的限制，其直徑僅僅只能達到數百個微米的等級。也就是說，量測像素射線的解析度會受限於微透鏡之尺寸大小。利用研究團隊過去對於次波長圓環孔徑(SAA)結構研究，將其長焦深、次波長聚焦能力之特色應用於波前感測器，此設計能夠提升波前感測器之空間解析度，增加像素射線量測的精確度。 對於像素射線的應用，在本論文之中以兩個儀器的發展方向為目標來進行。首先，次波長圓環孔徑結構陣列被用來改良傳統的Shack-Hartmann波前感測器。這個改良後波前感測器隨即被用來量測與重建650 nm波長的二極體波前，透過比較實驗量測所得波前和理論計算，不僅證明了像素射線法可以應用於波前量測與重建，同時也說明了運用SAA替代微透鏡陣列來建構波前感測器所能得到的性能提昇。 隨後，本論文將像素射線的概念應用於提昇顯微鏡系統的功能。在傳統顯微鏡系統中，景深隨著放大倍率的提升而降低。因此在顯微鏡下能夠看到清晰全貌的物體，通常只有數微米厚。對於較厚的觀測目標來說，顯微鏡不僅無法觀測到清楚的全貌，當然也無法取得觀測物體整個的立體外形。本研究利用光場相機的技術來截取像素射線資訊。所得成果證實此一創新技術，不僅可以突破以往顯微鏡景深的限制來取得各個焦平面的清楚影像，更可以利用其景深圖重建出待測物的三維外觀。 綜觀本論文的成果，此類方法的成功開發，除了可以開發各種量測儀器外，由於所完成的方法，可以將物體的3D外型及空間座標以極快的速度數位化，因此本論文所發展的方法，將可解決目前方興未艾的3D Printing，其前端物件空間座標不易快速取得的困境。
並列摘要
Pixel ray is a method that can be used to describe the light propagation behavior. Analyzing pixel ray information thus can lead to the development of various metrology systems. Some of the system developed based on pixel ray approach are the main foci of this thesis. Shack-Hartmann wavefront sensor is an instrument capable of retrieving pixel ray information. This thesis started by improving Shack-Hartmann wavefront sensor through circumventing the limitation imposed by the microlens array. More specifically, as the diameter of the microlens is around several hundred micrometers, the resolution achievable in traditional Shack-Hartmann wavefront sensor is also in the range of several hundred micrometers. More specifically, the resolution is limited by the size of the microlens. Following our prior research on sub-wavelength annular aperture (SAA), which possesses properties such as long depth of focus and sub-wavelength focusing capability, an improved wavefront sensor was developed. This design can improve the spatial resolution of wavefront sensor and also improve the precision of the pixel ray measurement. Two instrument based on pixel ray method were developed throughout the course of this research. First, sub-wavelength annular aperture was used to replace the microlens array in order to improve the performance of Shack-Hartmann wavefront sensor. This improved system was then used to measure and reconstruct the wavefront of a 650 nm wavelength diode laser. Comparing the measured wavefront with that of the theoretical value confirms that pixel ray method can be adopted to perform wavefront measurement. In addition, the improvement obtained by replacing the microlens array with SAA was also demonstrated. Secondly, the concept of pixel ray was implemented to pursue enhanced microscope system. In traditional microscope, depth of field decreases when higher magnification ratio objective is used. Thus, only few micrometer thickness of object can be observed under microscope clearly. For object with thickness large than this range, image will blur and object profile cannot be clearly reconstructed. This thesis applied the microlens array based light field camera technology to capture pixel ray information. The results confirmed that the microscope depth of field of system can be increased. The images obtained in different focusing plan can then be used to reconstruct the object’s full 3D profile In summary, the successful implementation of the pixel ray based approaches in this thesis can facilitate the development of various metrology instrument. In addition, since the 3D profile of arbitrary objects can be digitized quickly by using the methods developed in this thesis, data input that hindered the development of 3D printing can potentially be circumvented.