橢圓偏光儀在生物感測之擴展應用

Abstract

為了擴展光彈調變式橢圓偏光儀之應用，我們結合了表面電漿共振技術 (SPR) 以量測生物反應之橢圓偏光參數，藉以提高偵測生物系統之靈敏度。本系統提供一種雙頻道的量測方法: (1) 運用鎖相放大技術可以量測即時反應；(2) 使用數據擷取卡 (DAQ) 擷取調變之光學訊號，事後以快速傅立葉轉換技術分析，此量測方法僅需40μs。 而雙頻道的即時頻道可提供生物變化的時間參考以作事後分析的基礎。 利用光彈調變器為時序基礎來調變半導體雷射光源而形成頻閃照射模式 (stroboscopic illumination)，此技術可藉由電荷耦合元件 (CCD) 拍攝四個調變相位的光強度而達成二維橢圓偏光影像儀。 本實驗除了詳述系統的校正方法外，更進一步的展現蝕刻後之二氧化矽薄膜的三維影像與油滴在矽晶片上滑落的動態量測。此橢圓偏光影像儀可做較慢 (13 秒/面) 的變化。

This work is an extended application of photoelastic modulator (PEM) ellipsometry. This surface plasmon resonance technique combined with PEM ellipsometry provides higher sensitivity and temporal resolution to investigate the chemical activation and antibody immobilization process on thin gold films. We set up two detection channels in this configuration: one for real-time monitoring with a data rate of 1 set per second, and the other for post flight analysis with a data rate of 25000 sets per second. When a stroboscopic illumination technique is applied in a PEM ellipsometry, it can be conquered the slow imaging processing of charge-coupled device camera system and form a fast imaging ellipsometry. The synchronized ultrastable short pulse is used to freeze the intensity variation of the PEM modulated signal. The laser diode is modulated by a programmable pulse generator for triggering four short pulses at their specific temporal phase angle. The two-dimensional (2D) ellipsometric parameters can be deduced from those recorded four images. Therefore, the 2D thickness profile of a patterned sample can be measured.