使用雷射繞射儀與計量型原子力顯微鏡以從事奈米量測

Abstract

雷射繞射儀因為能校正奈米線距、二維標準片的角度與量測液體折射率，所以在實驗方面是一種重要的儀器。且光的繞射在物理中是大家熟知的現象，其量測的原理是把產生的繞射光反射對準原入射光的Littrow裝置，再經接收器量取繞射角度。線距的大小可以從產生的繞射角度與雷射光源的波長所決定。本研究還提出一種新方法來校正二維試片的角度，至於液體折射率則從浸潤在液體中的試片所產生的繞射光，經旋轉反射後量測產生的一階繞射角度而得。雷射繞射儀其對準與量測的過程都比其他儀器還來的簡單。雖然雷射繞射儀有非常準確的量測能力，不過僅能量測其線距的平均值，無法得知單一線距的大小與線距的圖案。所以建立完雷射繞射儀後，本研究還利用追溯式的原子力顯微鏡來量測線距。這兩者量測系統都基於不同的量測原理，且兩者方法都有不一樣的計量特性，因此可以相互印證。在比較兩種量測方法所產生的結果之後，利用雷射繞射儀所量測出來的結果，證明了使用追溯式原子力顯微鏡量測出來的結果。最後實驗結果顯示，本研究對於量測液體的折射率可以準確到小數點以下五位。此外，本研究還將昂貴的雷射光源換成雷射二極體，不僅大大地降低成本，也造就了自混頻繞射儀。

A laser diffractometer can calibrate grating pitch, 2D grating angle, and measure the refractive index of liquids. The measurement principle is based on the Littrow configuration, in which a reflective diffraction beam coincides with an incident beam. The pitch value is determined by the diffraction angle and laser wavelength. This study proposes a DAR method to calibrate the 2D grating angle. The refractive index is determined by rotating a reflective grating that is immersed in the fluid, and measuring the first-order Littrow diffraction angle. The alignment and measurement processes are easier than other instruments. Although the laser diffractometer is highly accurate, it can measure mean pitch value only. After establishing the laser diffractometer, in this study a traceable atomic force microscope (TAFM) is also used to measure the grating pitch. Comparing two kinds of measurement results show consistency between TAFM results and laser diffractometer results. Experimental results reveal that the proposed approach can be as precise as 0.00001 for the refractive index of liquids. Moreover, this work uses laser diodes as light source to develop self-mixing diffractometry, which significantly decreases cost.