Calculation Method for the Geometric Dimensions of a Scanning Near-Field Optical Microscope Optical Fiber Probe and Experimental Verification

掃描近場光學光纖探針之幾何尺寸計算方法和實驗驗證

林榮慶(Zone-Ching Lin) ； 周明和(Ming-Ho Chou)

《中國機械工程學刊》 40卷6期 (2019/12) Pp. 557-569

摘要

This study proposes an innovative calculation method for the geometric dimensions of a scanning near-field optical microscope (SNOM) optical fiber probe. We employ molecular mechanics and vibration theory to construct a simulative measuring model of a SNOM. We use a complex Boolean operation to arrange the probe and the sample atom-by-atom and then establish an atomic model for the simulative measuring model of SNOM. We conduct a scanning electron microscopy (SEM) photographing experiment to measure the geometric dimensions of the probe and then draw a relational diagram of the geometric dimensions and deduce their relational equations. We also find the potential energy parameter values of the Morse potential energy model among different atoms in order to solve the problem of the unknown potential energy parameter value by using the Lorenz-Berthelot mixing rule. We combine the optimal search of the Levenberg-Marquardt method with a reasonable convergence criterion to acquire the optimal geometric dimensions. In addition, a SNOM optical fiber probe is used to compare the results of the experimental and simulative measurements.

關鍵字

SNOM ； optical fiber probe ； simulative measurement ； geometric dimension

並列摘要

本文建立一個掃描近場光學（SNOW）光纖探針之幾何尺寸計算方法。我們應用分子力學和振動理論去建立一個SNOW的模擬量測模式。在建立SNOW的模擬量測模式中的原子模式，我們使用布林運算去安排探針和量測試片的原子模式。我們先做掃描電子顯微鏡（SEM）實驗，量測出探針的幾何尺寸並繪出光纖探針幾何尺寸的關係圖，進而推導出光纖探針的幾何尺寸的相關公式。我們並使Lorenz-Berthelot mixing rule去得到不同種類原子間的Morse potential energy的參數值。我們再用Levenberg-Marquardt方法進行最佳化的搜尋，配合合理的收斂準則，進而獲得最佳的光纖探針的幾何尺寸。此外，我們也使用SNOW的光纖探針進行幾何尺寸量測實驗，並比較實驗所得的光纖探針幾何尺寸和模擬所得的光纖探針幾何尺寸，驗證本文所建立的非破壞性光纖探針幾何尺寸計算方法為可行的。