近日，日本东京大学的Takuro Ideguchi及其研究团队取得一项新进展。经过不懈努力，他们研制出中红外宽视场纳米显微镜。相关研究成果已于2024年4月17日在国际知名学术期刊《自然—光子学》上发表。
该研究团队提出了一种实现宽视场MIR光热成像的最佳方案，旨在实现高空间分辨率。他们通过结合同步亚纳秒MIR和可见光光源的单物镜合成孔径定量相位成像技术，有效抑制了光热热扩散导致的分辨率退化效应。研究人员成功展示了远场MIR光谱成像，其空间分辨率受限于可见光衍射，在3.12-3.85μm（2,600-3,200cm-1）的MIR区域内，分别达到了120或175nm的半高全宽。该技术有望通过采用更短的可见波长或更高的物镜数值孔径，实现小于100nm的空间分辨率，为MIR宽视场纳米镜的应用开辟了新的道路。
据悉，中红外光谱(MIR)被广泛认为是一种强大的、无损的化学分析方法。然而，它的实用性受到微米尺度空间分辨率的限制，这是由长波MIR衍射极限所引起的。MIR光热成像技术成功突破了这一限制，该技术利用可见光显微镜检测MIR吸收器附近产生的光热效应。尽管该技术展现出广阔的应用前景，但目前其空间分辨能力的全部潜力尚未完全实现。
附：英文原文
Title: Mid-infrared wide-field nanoscopy
Author: Tamamitsu, Miu, Toda, Keiichiro, Fukushima, Masato, Badarla, Venkata Ramaiah, Shimada, Hiroyuki, Ota, Sadao, Konishi, Kuniaki, Ideguchi, Takuro
Issue&Volume: 2024-04-17
Abstract: Mid-infrared (MIR) spectroscopy is widely recognized as a powerful, non-destructive method for chemical analysis. However, its utility is constrained by a micrometre-scale spatial resolution imposed by the long-wavelength MIR diffraction limit. This limitation has been recently overcome by MIR photothermal imaging, which detects photothermal effects induced in the vicinity of MIR absorbers using a visible-light microscope. Despite its promise, the full potential of its spatial resolving power has not been realized. Here we present an optimal implementation of wide-field MIR photothermal imaging to achieve high spatial resolution. This was accomplished by employing single-objective synthetic-aperture quantitative phase imaging with synchronized subnanosecond MIR and visible light sources, effectively suppressing the resolution-degradation effect caused by photothermal heat diffusion. We demonstrated far-field MIR spectroscopic imaging with a spatial resolution limited by the visible diffraction, down to 120 or 175nm in terms of the Nyquist–Shannon sampling theorem or full-width at half-maximum of the point spread function, respectively, in the MIR region of 3.12–3.85μm (2,600–3,200cm-1). This technique—through the use of a shorter visible wavelength and/or a higher objective numerical aperture—holds the potential to achieve a spatial resolution of less than 100nm, thus paving the way for MIR wide-field nanoscopy.
DOI: 10.1038/s41566-024-01423-0
Source: https://www.nature.com/articles/s41566-024-01423-0