發光二極體(light emitting diode, LED)具備省電、壽命長、色彩多變、環保、以及反應速度快等優點，已取代傳統光源，成為備受矚目的新一代光源科技。為了滿足LED於不同應用上需求(例如，光電顯示與照明科技等)，準確地檢測或鑑定LED輻射樣本(radiation pattern)是非常重要的。例如，測定LED的輻射樣本，能妥善且有效地利用LED的視角(viewing angle)與發光效率(lighting efficiency)，並藉此改善LED熱耗散(thermal dissipation)或能量消耗(power consumption)、以及使用人員安全性的問題。因此，發展LED光輻射分佈特徵量測技術在光電顯示與照明科技與產業有相當重要的意義。
本論文的研究目的主要可區分為以下兩個重點：
(1) 首先，我們針對以光二極體(photodiode, PD)感測技術為基礎的系統組態，來進行理論分析與數學描述。我們利用角空間頻率(angular spatial frequency)之概念來詮釋系統的量測解析度，並經由實驗來驗證PD感測技術的空間濾波效應(spatial filtering effect)，以及LED輻射樣本的空間頻率。亦針對不同的量測方法(如，二維照度量測法)，經由實驗驗證的方式來進行量化分析，並比較出各種方法之間的優劣點。
(2) 再者，我們根據性能評估的結果，提出一套快速且較準確的量測系統，來測定各種不同亮度LED的輻射樣本。在此論文中，一個快速鎖定放大(lock-in amplifier, LIA)技術被呈現出來，此技術的功能在於能有效地即時濾除雜訊/雜光，避免系統受外界雜訊干擾而增加量測的不確定性。
本論文所提出的系統架構僅含有一個PD感測電路、兩個步進馬達、一個快速LIA裝置、以及一組數位訊號處理(digital signal processing, DSP)平台，其系統結構簡單，且具有高成本效益。針對此系統，論文中我們利用漸進的方式，依循學理、模擬、實驗與系統製作的方法，並且說明整體的可行性分析。實驗的結果顯示此方法所量測的結果是相當令人滿意的。
最後，我們利用此系統來進行多顆LED光源模組的均勻度測試，經由此系統我們能有效地測定光源模組的均勻性，並決定較佳的LED陣列排列方式。相信此一論文對於LED顯示/照明技術之學術研究與產業發展將有相當大的助益。

For years, light-emitting diodes (LEDs) have been recognized as a generation of new light sources because they possess the properties of energy-saving, environmental friendly, and long lifetime, and those surpassing in traditional lighting. To satisfy the requirements for different applications, such as for displays and illuminations, determining LED radiation patterns is important to utilizing their viewing angle and lighting efficiency, so that the difficulties of thermal dissipation (power consumption) and safety are resolved.
To achieve the objectives, a fast LED radiation pattern characterization system is proposed. In this thesis, we focus on two major works as follows. The first is to give a mathematical formulation for the PD sensing measurement methods and to quantitatively analyze the different methods (e.g., two-dimensional irradiation measurement) through experiments. In the experiments, the spatial bandwidth of LED radiation patterns and the spatial filtering effect due to PD sensing are to be verified. The second is to design and develop a fast measurement system for the radiation patterns of wide-range brightness LEDs. Due to the real-time noise suppression performance of the proposed system, the requirements of fast of quality control and classification for a variety of LEDs will be achieved.
In this thesis, a fast lock-in amplifier (LIA) technique has been presented to perform real-time noise suppression. The LIA scheme of the system simply employs a PD sensing circuit, two stepping motors, a fast analog dual LIA device, and a DSP-platform to achieve the measurement. Thus, the configuration of such a system is quite simple and it is consequently cost-effective. The system has been achieved and verified through the experiments. Experimental results indicate that the proposed system gives a satisfactory result. It appears that the proposed approach can establish an accurate optical modeling for LED devices. Finally, the proposed system can evaluate the uniformity of the multiple-LED module to determine the optimum packing density of LED arrays for display/illumination technologies. We expect that it would be highly beneficial to the development of related industries for the techniques of LED applications/manufacturing.

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