以光斑對比擷取生物組織內的光動態擴散影像

Imaging the Dynamic Light Propagation in Biological Tissue by Speckle Contrast

陳世偉(Shih-Wei Chen)

指導教授 ： 蔡正倫

中原大學/工學院/醫學工程研究所/碩士(2003年)

https://doi.org/10.6840/cycu200300067

摘要

生理訊號的光學量測方法，正隨著光學元件與技術的發展，迅速地進步與普及，而同調光在生物組織內的散射性干涉是許多利用干涉做為原理之生醫光學量測的基礎，或者是造成了量測上的限制，研究光的同調性在生物組織中的改變將有助於開發新的應用，或突破原有量測的限制。且使用低同調光干涉原理來量測光在生物組織內散射及擴散情形，藉以瞭解光在生物組織內分佈的範圍與光的擴散路徑。
此量測系統架設是Mach-Zender干涉儀，利用雷射二極體（光波長659nm ± 10nm）驅動電流的大小來改變光源的同調程度，將其照射在散射樣本表面的邊緣後，此同調光先經過組織的多重散射再從側面射出時，由樣本的側面可觀察到所形成的斑點干涉分佈影像，再以另一束參考光形成光在組織中的動態擴散影像。
量測的結果並將與利用蒙地卡羅模擬方法發展出來之數學模型的模擬結果做比較，藉由反覆比對與嘗試，以找出光在生物組織內的分佈範圍、光的擴散路徑與生物組織的光學係數。

關鍵字

光學係數 ； 同調性 ； 散射性干涉 ； 蒙地卡羅模擬 ； 低同調光干涉

並列摘要

Applications of optical measurement methods for physiological signals have become very popular because of the great progress in optical components and techniques. The interference of scattering coherence light inside biological tissues is the basic working principle of many biomedical optics measurements. But sometimes, it causes a restriction of measurement range. A better understanding of the interaction between coherence light and biological tissue will be helpful in developing new measurement techniques or overcome the restrictions. A low coherent interferometer system was used to detect the dynamic migration of photon in biological tissues. This measurement would be helpful in understanding how photons propagate in biological tissues.
The structure of the measurement system is Mach-Zender interferometer. The coherence of a semiconductor laser will be adjusted by controlling its driving current. Light will be injected into a scattering sample close to the edge of front surface. The injected photons will encounter multiple scattering before they are absorbed or escape from the front surfaces. Speckle distribution images will be observed on the front surfaces. Using an another reference beam to make the dynamic light propagation in biological tissue.
The measurement image also will be compared with the result of Monte Carlo simulation. Comparison between measurement and simulation results has to be done repeatedly with modification of mathematical model until the best fit between them is found.

並列關鍵字

Monte Carlo simulation ； Coherence ； Low coherence interference ； Scattering interference

參考文獻

1.Aizu, Y., K. Ogino, T. Koyama, N. Takai, and T. Asakura, “ Evaluation of retinal blood flowusing laser speckle,” J. Jpn. Soc. Laser Med., vol. 8, 89-90, 1987.

2.Briers, J. D., “Wavelength dependence of intensity fluctuations in laser speckle patterns from biological specimens,” Opt. Commun., vol. 13, 324-326, 1975.

3.Briers, J. D., “Laser Doppler and time-varying speckle: a reconciliation,” J. Opt. Soc. Am., vol. 13(2), 345-350, 1996.

4.Chiang, H. P., Wang J., “Imaging through animal tissues with CW diode laser based broadband interferometry.” optics communications, vol. 130, pp.317-326, 1996.

5.Dunn, A. K., H. Bolay, M. A. Moskowitz, and D. A. Boas, “Dynamic Imaging of Cerebral Blood Flow Using Laser Speckle,” J Cereb. Blood Flow Metab., vol. 21(3), 195-201, 2001.