TIME-RESOLVED SPECTROSCOPY BY AMPLITUDE MODULATION INDEX

通过调幅指数进行时间分辨光谱

• 批准号: 3501911
• 负责人: MAO-ZHU ZHANG
• 金额: $ 5万
• 依托单位: NEAR INFRARED MONITORING, INC. (NIM)
• 依托单位国家: 美国
• 财政年份: 1990
• 资助国家: 美国
• 起止时间: 1990-08-01 至 1991-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3501911
• 关键词: biomedical equipment development; human tissue; interferometry; spectrometry; visible light

The use of phase modulation in recording the time constant for the decay of the photons exiting f rom human organs such as brain and limbs has led to the development of several successful devices, in which precise control of oscillator frequencies has resulted in photon migration measurements accurate to a few millimeters using frequencies of 220 MHz. Recent improvements in sensors employing silicon diode detectors suggest that frequencies approaching 500 MHz can be used. At this frequency the amplitude modulation index of the emergent photons depends upon the path length as, for example, in the attenuation characteristic of a parallel RC network. Whereas the phase characteristic Of such an RC network for tissue studies has been previously emphasized, in this case we propose a novel development in which the amplitude charaCteristic of the photon migration is studied. In this grant application we propose to evaluate measurement of the amplitude index at 440 MHz with 140 MHz as a reference frequency. The proposed instrument measures the ratio (or difference) of the amplitude modulation index at a low and a high frequency and at two wavelengths. The attenuation characteristic at the two frequencies and two wavelengths becomes, a measure of path length changes. Demonstrations in a model system and in human tissues at 97 and 220 MHz ensure the feasibility of the proposal.

相位调制在记录衰减时间常数中的应用 从人体器官如大脑和四肢发出的光子导致 几个成功的设备的发展，其中精确控制的 振荡器频率导致光子迁移测量 使用220 MHz的频率精确到几毫米。最近 采用硅二极管检测器的传感器的改进表明， 可以使用接近500 MHz的频率。在这个频率下， 出射光子的振幅调制指数取决于路径 例如，在并联RC的衰减特性中， 网络然而，这种用于组织的RC网络的相位特性 研究已经强调，在这种情况下，我们提出了一个新的 光子迁移的振幅特性 研究了 在这项资助申请中，我们建议评估 振幅指数为440 MHz，参考频率为140 MHz。的 所提出的仪器测量振幅的比率（或差 在低频和高频以及在两个波长处的调制指数。的 双频双波长衰减特性 成为，路径长度变化的度量。模型系统中的演示 在97和220 MHz的人体组织中， 提议