近場掃描式光學顯微鏡提供了空間解析度小於繞射極限的光學資訊，而光纖式近場掃描式光學顯微鏡由於光纖易受到其截止效應、熱傷害等現象影響到其解析度，故發展出了無孔徑的近場掃描式光學顯微鏡。
本論文主要研究目的在於以原子力顯微鏡為基礎，建立一套無孔徑近場掃描式光學顯微鏡，藉由自差式干涉與外差式干涉技術的使用擷取光學訊號。而擷取的光學散射信號包含了探針與奈米結構交互作用的近場光學信號以及結構表面散射等作用產生的背景信號，將此信號經過鎖相放大器之解調變以獲得奈米結構的近場光學資訊。藉由資料擷取卡或數位信號處理器嵌入式系統做為控制核心，整合周邊的操控元件，並對此系統目前的穩定度進行校正以及針對量測得到的實驗結果進行訊噪比之評估。

Near-field scanning optical microscopy (NSOM) provides an optical spatial resolution below the diffraction limit. However, the resolution of the conventional aperture NSOM with a metal-coated fiber is confined greater than 50nm due to waveguide cut-off effect and thermal noise. In order to improve the spatial resolution, an apertureless NSOM (aNSOM) has been developed.
In this thesis, an aNSOM based on a commercial AFM is attempted to develop by intergrading a nanopositioning stage and other opto-electronic instruments. The near field optical information is detected by utilizing homodyne and heterodyne modulation detections. The optical signal includes the light scattered by the tip, interacted with sample in near-field, scattered by sample to induce background signal. The far field signal is detected by avalanche photodiode, and then the near-field optical information from the tip interacted with the sample is demodulated by a lock-in amplifier. All the signals and instruments are collected and controlled by using a data acquisition (DAQ) card and an embedded system based on a digital signal processing (DSP) board. Finally, the stability of system is calibrated and the signal-to-noise ratio is evaluated.

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