Ultrafast chemical imaging by widefield photothermal sensing of infrared absorption

作者：Yeran Bai, Delong Zhang, Lu Lan, Yimin Huang, Kerry Maize, Ali Shakouri, Ji‐Xin Cheng · 发表于：Science Advances · 年份：2019 · DOI：10.1126/sciadv.aav7127 · 被引用次数：154 · 研究领域：Spectroscopy Techniques in Biomedical and Chemical Research、Spectroscopy and Chemometric Analyses、Thermography and Photoacoustic Techniques

Infrared (IR) imaging has become a viable tool for visualizing various chemical bonds in a specimen. The performance, however, is limited in terms of spatial resolution and imaging speed. Here, instead of measuring the loss of the IR beam, we use a pulsed visible light for high-throughput, widefield sensing of the transient photothermal effect induced by absorption of single mid-IR pulses. To extract these transient signals, we built a virtual lock-in camera synchronized to the visible probe and IR light pulses with precisely controlled delays, allowing submicrosecond temporal resolution determined by the probe pulse width. Our widefield photothermal sensing microscope enabled chemical imaging at a speed up to 1250 frames/s, with high spectral fidelity, while offering submicrometer spatial resolution. With the capability of imaging living cells and nanometer-scale polymer films, widefield photothermal microscopy opens a new way for high-throughput characterization of biological and material specimens.