Comb Light Source/Imaging spectrometer for advanced Spectral Domain Optical Coherence Tomography

用于先进谱域光学相干断层扫描的梳状光源/成像光谱仪

• 批准号: 10242951
• 负责人: Brian E. Applegate
• 金额: $ 19.36万
• 依托单位: UNIVERSITY OF SOUTHERN CALIFORNIA
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-01 至 2023-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10242951
• 关键词: Address; Algorithmic Software; Algorithms; Area; Auditory; Blast Injuries; Blood flow; Code; Comb animal structure; Complex; Coupled; Custom; Detection; Development; Ear; Ensure; Environment; Floor; Functional Imaging; Hearing; Human; Image; Labyrinth; Lasers; Length; Light; Measures; Methods; Modality; Morphologic artifacts; Neurons; Noise; Optical Coherence Tomography; Output; Patients; Performance; Phase; Reproducibility; Resolution; Signal Transduction; Source; System; Systems Development; Systems Integration; Techniques; Time; Validation; awake; base; detector; elastography; experience; imaging approach; interest; mechanical properties; middle ear; molecular imaging; mouse model; normal aging; novel; optical fiber; vibration

There is a growing interest in the development of functional imaging with Optical Coherence Tomography (OCT). Many of these approaches to functional imaging rely on the exquisite phase sensitivity of the OCT interferometer. These include well established techniques like Doppler OCT for measuring blood flow as well as emerging applications like OCT elastography for measuring mechanical properties, and Magnetomotive OCT and Photothermal OCT for molecular imaging. Our own interest lies in the area of vibrometry. Swept laser systems are advantageous because they enable the use of Mach-Zehnder type interferometers with balanced detectors. This provides for cancelation of common mode noise, the DC component, and autocorrelation artifacts. The most advanced commercially available swept lasers also have a very long coherence length (>1 m), hence signal roll-off as a function of depth is negligible. Taken together these qualities result in images that have fewer artifacts and increased signal-to-noise with concomitant high phase stability and vibrational sensitivity. Most commercially available swept lasers suffer from instabilities in the laser sweep such that every sweep needs to be calibrated in order to maintain high phase-stability. Ourselves and others have developed methods to accomplish this, but at the expense of substantial hardware complexity and sophisticated algorithms to ensure that wavenumber as a function of time, k(t), is known precisely for each sweep. In our experience, small changes in the system, environment, and the normal aging of the laser, forces frequent “tweaking” of the system to maintain the highest phase-stability. One company has developed a swept laser, where k(t) is linear and highly reproducible. We have shown that this source provides high phase- stability without the need of the complex hardware/software algorithms. The drawback to this laser system is its limited spectral bandwidth (typically 90-95 nm) and its limited availability. On the other hand, spectrometer based systems offer high-phase stability, but typically with relatively short coherence lengths (1-3 mm) and without the advantages of balanced detection. However, they can provide wide spectral bandwidth with concomitant higher resolution while maintaining high phase-stability. Here we propose to develop a novel comb light source spectrometer based system that has all of the advantages of a swept laser system, but with the inherent phase-stability of a spectrometer based system. Aim 1: Develop a comb laser source centered at ~1300 nm, with a bandwidth of 125-150 nm, and 1024 discrete lines over ~200 nm. The coherence length of each line will be at least 8 cm, providing a 4 cm 3 dB roll-off. Aim 2: Develop an imaging spectrometer with a magnification of 0.5 that disperses the light linearly (in k) over the 200 nm bandwidth using a custom compound prism, having a line rate of 147 kHz. Aim 3: Integrate the light source and spectrometer into a balanced spectral domain OCT system, validate performance, and develop FPGA code for pipelined real-time computation of the differential signal.

光学连贯性层析成像的功能成像的发展越来越感兴趣 （OCT）。这些功能成像的方法中有许多依赖于OCT的独家阶段灵敏度 干涉仪。这些包括良好的技术，例如多普勒OCT，用于测量血流以及 新兴应用，例如用于测量机械性能的OCT弹性图和磁性OCT 和用于分子成像的光热OCT。我们自身的兴趣在于振动法。 扫掠激光系统是有利的，因为它们可以使用Mach-Zehnder类型的干涉仪 平衡探测器。这提供了取消公共模式噪声，直流组件和 自相关工件。最先进的市售激光器也有很长的 相干长度（> 1 m），因此信号滚动随深度的函数而言是可忽略的。综合这些品质 导致图像较少的伪影且随之增加的高相位稳定性增加了信噪比 和振动灵敏度。大多数市售的扫掠激光器都遭受激光扫荡的不稳定性 因此，为了保持高相位稳定性，需要校准每次扫描。我们自己和他人 已经开发了实现这一目标的方法，但以实质性的硬件复杂性为代价 精致的算法确保波数作为时间k（t）的函数，恰好是每种算法 扫。根据我们的经验，激光的系统，环境和正常老化的力量很小 通常“调整”系统以保持最高的相位稳定性。一家公司已经发展了 激光，其中k（t）是线性且高度可重现的。我们已经表明，该来源提供了高相 - 稳定性无需复杂的硬件/软件算法。该激光系统的缺点是 其有限的光谱带宽（通常为90-95 nm）及其有限的可用性。另一方面， 基于光谱仪的系统具有高音稳定性，但通常具有相对较短的相干长度（1-3 mm），没有平衡检测的优势。但是，它们可以提供宽光谱带宽 在维持高相位稳定性的同时，伴随着更高的分辨率。 在这里，我们建议开发一个具有所有优点的基于梳子光源光谱仪的系统 扫描激光系统，但具有基于光谱仪的系统的继承相位稳定性。目标1：开发一个 梳子激光源以〜1300 nm为中心，带宽为125-150 nm，1024个离散线超过200行 NM。每条线的相干长度至少为8厘米，提供4厘米3 dB的滚动。目标2：开发一个 成像光谱仪的放大倍数为0.5，在200 nm上线性分散（以k）的光线 使用自定义复合棱镜的带宽，线路速率为147 kHz。目标3：整合光源 光谱仪和光谱域OCT系统，验证性能并开发FPGA代码 用于管道的差分信号实时计算。