波長可調之可見光奈秒雷射及其於功能性光學解析度之光聲顯微術的應用

Wavelength-tunable visible pulse generation for functional optical resolution photoacoustic microscopy

陳映如(Chen, Ying Ju)

指導教授 ： 楊尚達

國立清華大學/電機資訊學院/光電工程研究所/碩士(2015年)

摘要

近年來，跨領域的科學研究備受關注，其中生醫光電也是個熱門的議題，此研究主要是開發可調式波長之可見光奈秒脈衝雷射應用於血氧濃度的估測以及光學解析度的光聲顯微術。由於血氧濃度的估測需要包含等消光點在內的兩個波長、窄線寬(數奈米)、足夠的能量(100奈焦耳)以及穩定良好的模態(TEM00)的脈衝雷射，故此光源利用串聯非線性波長轉換(倍頻、光參震盪器、和頻)並結合光纖耦合的方式得到所需脈衝光源。其中，扇形週期性反轉鈮酸鋰晶體、致冷晶片的應用，使得此光源能夠快速的變換波長。
在光聲實驗中分別利用波長545 奈米(等消光點)、552奈米的脈衝雷射打入仿體中，藉由不同波長的光聲訊號進而得知仿體的濃度變化。實驗結果顯示仿體濃度估測誤差值可以小於8%，而掃描解析度可達約5微米。

關鍵字

準相位匹配 ； 光參震盪器 ； 光學解析度光聲顯微術

並列摘要

Recently, interdisciplinary science researches have been paid much attention, and biophotonics is a popular topic. This thesis focuses on the development of wavelength-tunable visible pulse generation for hemoglobin oxygen saturation (SO2) estimation and optical resolution photoacoustic microscopy (OR-PAM). SO2 estimation requires a tunable laser possessing two wavelengths which include an isosbestic point, narrow linewidths (1-2 nm), enough pulse energy (100 nJ), and stable transverse mode (TEM00) . Therefore, our laser light source uses a cascaded nonlinear wavelength conversion; second harmonic generation(SHG), optical parametric oscillator(OPO), sum frequency generation SFG) with single mode fiber (SMF) coupling. Moreover, we are able to convert wavelengths fast with the aid of a fan-out periodically poled lithium niobate (PPLN) crystal and thermoelectric cooler (TEC).
In photoacoustic experiments, the pulse laser at 545 nm (an isosbestic point) and 552 nm is sent into a phantom, respectively. Variation of concentration in a phantom is obtained through photoacoustic (PA) signals from different wavelengths. Experimental results shows that errors of SO2 estimation in a phantom are below 8%, and the spatial resolution is around 5 um.

並列關鍵字

Quasi-phase matching ； Optical parametric oscillator ； Optical resolution photoacoustic microscopy

參考文獻

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