NOVEL METHOD FOR OPTICAL COHERENCE TOMOGRAPHY AND MULTIPLEXED SENSING

光学相干层析成像(OCT)允许高深度分辨率成像，在过去的5年里受到了人们的极大关注，使运算速度提高了100倍，并扩展到了各种成像问题。OCT主要有两种类型：时域(TD)和谱域(SD)。最近在速度上的进步是由SD-OCT领域的开发人员实现的。然而，SD-OCT也有一些TD-OCT所没有的缺点。SD-OCT的研究也促进了新型快速可调谐激光器的发展，即所谓的扫频源(SS)。为了理解和控制用于SS-OCT的光源所用的包含光放大器的闭合光环中的现象，人们已经付出了巨大的努力。本方案提出了一种新型的OCT和一种新型的光学干涉仪。这是由于需要解决TD-OCT方法在速度方面的限制、内面OCT的潜力(迄今尚未研究)、产生3D OCT勘探的潜力、SD-OCT方法的范围和动态焦点方面的限制以及所有OCT方法的色散补偿。所提出的新方法和装置是受扫频源和SS-OCT的发展启发而提出的。作为TD-OCT和SD-OCT方法的结合体，研究了一类新的OCT系统。新的OCT方法消除或改进了SD-OCT方法的缺点。该方法具有与TD-OCT和SD-OCT兼容的通用性。申请人已经证明了保证研究成功的操作原则。然而，这里将要研究的SD-OCT和TD-OCT之间的联姻所承诺的远比迄今为止的演示装置所展示的要多得多，因此寻求研究支持来探索新方法的多种途径。这可能会给OCT领域带来革命性的变化，以及目前OCT技术无法实现的开放应用，例如深度超过1厘米(眼睛)的物体的SD-OCT，或者移动器官或组织的面部成像(以秒为单位的整个视网膜体积的成像，在所有方向上的采样都比最先进的SD-OCT设置更好)。要研究的方法将允许扫描制度和操作模式的组合，以在测量、诸如眼睛、心脏或运动胚胎的3D成像中实现多功能，或者通过利用角度合成或偏振来实现功能/低噪声成像。新的方向是在确定血管中的液体(血液)流动轮廓时瞬时消除组织的运动影响、跟踪物体(角膜或视网膜)的轴向位置、自动色散补偿以及在轴向扫描中改善相干门和焦点之间的同步性(这两种SD-OCT方法都存在问题)。该方法同样适用于传感器的多路复用。在多个路径长度上同时测量成为可能。将组装三个概念验证演示器，使用内面TD-OCT、快速和远程跟踪以及用于长轴向扫描的源系统在不同深度进行多次成像。

Optical coherence tomography (OCT) allows high depth resolution imaging and has received considerable interest in the last 5 years, which resulted in a 100 times increase in the speed of operation and extension to a large variety of imaging problems. There are two main types of OCT: time domain (TD) and spectral domain (SD). The recent progress in speed has been achieved by developers working in the SD-OCT field. However, SD-OCT has several disadvantages, non present in TD-OCT. The research in SD-OCT has also stimulated the development of novel fast tunable lasers, the so called swept sources (SS). Tremendous effort has been put in understanding and controlling the phenomena in closed optical loops containing optical amplifiers for optical sources to be used in SS-OCT. The present proposal puts forward a novel type of OCT and a novel class of optical interferometers. This is driven by the needs to address the limitations in terms of speed of the TD-OCT method, by the potential of the en-face OCT, not investigated so far, in producing 3D OCT exploration and by the limitations in terms of range and dynamic focus of the SD-OCT methods as well as dispersion compensation of all OCT methods. The novel method and devices proposed are inspired by the progress in swept sources and SS-OCT. A new class of OCT systems is researched, as a marriage between the TD-OCT and SD-OCT methods. The new OCT method eliminates or ameliorate the disadvantages of the SD-OCT method. The novel method presents the generality of being compatible with both TD-OCT and SD-OCT. The applicant has demonstrated the principle of operation which guarantees the success of research. However, the marriage between the SD-OCT and TD-OCT to be researched here promises much more than what the demonstrator set-up has shown so far, therefore research support is sought to explore the multiple avenues of the novel method. This may revolutionise the field of OCT and open applications not currently possible with the present OCT technology, such as SD-OCT of objects extended in depth by more than 1 cm (eye), or en-face imaging of moving organs or tissue (of the whole retina volume in fractions of a second, with better sampling in all directions than achievable with the most advanced SD-OCT set-up). The method to be researched will allow combination of scanning regimes and modes of operation to achieve versatile functionality in measurements, in the 3D imaging of moving tissue such as the eye, heart, or moving embryos or functional/low noise imaging by making use of angular compounding or polarisation. Novel directions are opened in the instantaneous elimination of the movement effects of the tissue when determining the liquid (blood) flow profile in a vessel, in tracking the axial position of objects (cornea or retina), automatic dispersion compensation as well as improvement in the synchronism between the coherence gate and the focus in axial scanning (a problem for both types of SD-OCT methods). The method proposed is also applicable in multiplexing of sensors. Simultaneous measurements over multiple path lengths become feasible. Three proof of concept demonstrators will be assembled, for multiple imaging at different depths using en-face TD-OCT, fast and long range tracking and swept source systems for long axial scanning.