Advanced signal processing for dual comb interferometry

双梳光谱学是近年来已经非常成熟的范例。它基本上是从一个实验室的好奇心，由几个团体倡导，并表现出潜力，实际上找到“现实世界”的应用，如泄漏检测在石油和天然气田。该技术使用两个高精度激光器，每个激光器发射良好控制的离散频率。激光梳的辐射被控制（或已知）一个方面到另一个惊人的精度，超过15个小数位！这些梳子被用来探测物质，从远处检索几种化合物的独特特征。 在光谱学中，频率梳提供比经典方法更好的分辨率和灵敏度。当试图检测复杂混合物中的痕量成分时，梳状光谱学尤其闪耀。在宽光谱范围内的高分辨率使得能够区分独特的特征，确切地说是阅读丰富组分的“线之间”，同时高灵敏度允许检测污染物的百万分之一或十亿分之一。 第一个重要的应用是温室气体监测。有几种气体，即使是微量的，也是我们碳预算的重要贡献者。甲烷和乙烷的情况就是如此，其监测不仅对确保行业符合法规、各国遵守国际协议至关重要，而且对减少资源浪费也至关重要，因为约2%的天然气因泄漏而损失。第二种应用是通过呼吸检测进行诊断。就像呼吸分析仪可以量化血液中的酒精含量一样，类似的设备可以检测不同的挥发性有机化合物，这些化合物在呼吸中的浓度表明了几种疾病。例如，氨的痕迹表明肾脏问题，而丁烷标志着肺癌。 在给定分辨率和测量时间的可实现灵敏度方面，梳状光谱具有非常好的品质因数。然而，在增加测量的激光功率的可能性方面受到严重限制。检测链中的非线性和系统误差很快就会出现。这些是已知的，因为十年来，但不是最严重的罪犯在采用该技术，所以他们没有得到妥善处理，从纠正的角度来看。现在，他们限制了几个测量，这个计划提出解决这些问题。这将允许更好地使用可用的激光功率，更好的检测灵敏度和更快的测量，有助于解锁实际应用。加拿大在光学光谱方面拥有强大的工业基础，几个省的公司向全球不同的细分市场销售仪器：从食品和药品生产线的质量控制到安全和环境监测的遥感。加拿大的工业接收器已经到位。

Dual comb spectroscopy is a paradigm that has greatly matured in recent years. It basically went from a lab curiosity championed by a few groups and exhibiting potential to actually finding "real-world" applications such a leak detection in oil and gas fields. The technique uses two high precision lasers each emitting well controlled discrete frequencies. The radiation of the laser combs is controlled (or known) one respect to the other to astounding accuracy, over 15 decimal places! Those combs are used to probe matter retrieving, from a distance, unique signatures for several chemical compounds. In optical spectroscopy, frequency combs provide better resolution and sensitivity than classical approaches. Comb spectroscopy shines particularly when trying to detect trace constituents in complex mixes. The high resolution over a broad spectral range enables distinguishing between unique signatures, quite literally reading "between the lines" of abundant components while the simultaneous high sensitivity permitting parts per million or per billion detection of contaminants. A first important application is greenhouse gases monitoring. Several gases when present even in trace amounts are significant contributors to our carbon budget. This is the case for methane and ethane whose monitoring is essential not only to make sure that industries meet regulations, that countries respect international agreements but also to reduce waste of resources since around 2% of natural gas is lost through leaks. A second application is diagnosis through breath detection. Much like a breath analyser can quantify your blood alcohol level, a similar device could detect different volatile organic compounds whose concentration in breath is indicative of several diseases. For instance, traces of ammonia indicate renal issues while butane marks lung cancer. Comb spectroscopy has a very good merit factor in terms of achievable sensitivity for a given resolution and measurement time. It is however severely limited in the possibility of increasing measured laser power. Non-linearity in the detection chain and systematic errors quickly arise. These are known since a decade but were not the worst offenders in the adoption of the technique, so they were not properly addressed from a correction perspective. Now that they limit several measurements, this program proposes addressing these issues. This will allow better use of available laser power, better detection sensitivity and faster measurements, contributing in unlocking practical applications. Canada has a strong industrial base in optical spectroscopy, with companies in several provinces selling instruments worldwide to different market segments: from quality control in food and pharmaceutical production lines to remote sensing for security and environmental monitoring. Canadian industrial receptors are already in place.