Fast IR Imaging with Sub-wavelength Resolution Using a Transient Near-field Probe (Tipless Near-field Microscopy)

9819778使用瞬变近场探头的亚波长分辨率快速红外成像(无抖动近场显微镜)通过利用分子的固有对比参数--分子的中红外振动模式--获得的生物系统的亚微米分辨率的“化学”图像开始在研究中发挥重要作用。由于感兴趣区域的波长通常为几微米，因此只能通过使用近场技术来获得这样高分辨率的图像。到目前为止，这种技术依赖于某种形式的亚微米尺寸的机械探头或尖端，并机械扫描整个表面，同时保持与表面的固定亚微米距离。我们建议开发一种新的近场显微镜方法，其中成像基于远程、光学产生的瞬时近场探头。皮秒可见光脉冲入射到半导体衬底表面，通过光致反射现象，将产生尺寸由衬底上可见光光斑大小决定的瞬变反射镜。由这种亚波长大小的反射镜散射的红外光将在穿过位于衬底上的样品的传播过程中被收集。由于样品位于衬底上，不需要近场距离控制，图像将以传统激光扫描显微镜的速度获得。此外，由于近场探测器是使用光远程产生的，因此要成像的样品可以被透明液体或固体覆盖或包裹在其中。显微镜将把传统的倒置显微镜与红外成像系统结合起来，在光谱的可见光和红外部分同时提供快速的亚微米成像。除了传统的组织切片，生物系统，包括活细胞，将能够在液体介质中成像。

9819778AbstractFast Infrared Imaging with Sub-Wavelength Resolution Using aTransient Near-Field Probe (Tipless Near-Field Microscopy)Sub-micron resolution "chemical" images of biological systems obtained through use of the intrinsic contrast parameters of molecules - their mid-infrared vibrational modes -are beginning to play an important role in research. Because the wavelengths in the region of interest are typically several microns, such high resolution images can only be obtained through the use of near-field techniques. To date, such techniques have relied upon some form of mechanical probe or tip made with sub-micron dimensions and mechanically scanned across the surface to be imaged while being maintained at a fixed sub-micron distance from the surface.We propose the development of a new approach to near-field microscopy in which imaging is based on a remote, optically generated transient near-field probe. Picosecond pulses of visible light incident on the surface of a semiconductor substrate will produce, through the phenomenon of photo-induced reflectivity, transient mirrors with dimensions determined by the size of the visible beam spot on the substrate. Infrared light scattered by such a sub-wavelength sized mirror will be collected afier propagating through the sample located on the substrate. Since the sample is located on the substrate, no near-field distance control will be required, and images will be available at the rate of conventional laser scanned microscopes. Further, since the near-field probe is generated remotely -using light - the sample to be imaged can be covered by, or encased in, a transparent liquid or solid.The microscope will combine a conventional inverted microscope with an infrared imaging system providing rapid sub-micron imaging simultaneously in the visible and infrared parts of the spectrum. In addition to conventional histologic sections, biological systems, including living cells, will be able to be imaged in liquid media.