Overview and Application of Scanning Near-field Optical Microscopy
Scanning Near Field Optical Microscopy (SNOM) is an optical scanning probe microscopy (SPM) technique developed based on the principle of near-field detection. Its resolution has exceeded the optical diffraction limit, reaching 10-200. m. In terms of technological applications, SNOM provides a powerful tool for single-molecule detection, research on biological structures, nano microstructures, semiconductor exocytosis analysis, and substructure studies; In physics, it combines multiple disciplines such as quantum optics, waveguide optics, and dielectric physics, and thus opens up a new field of optical research - Near field optics (OptiCS). 1. The development history and current research status of SNOM at home and abroad. According to the Abbel principle, the resolution of traditional optical microscopes is limited by the optical diffraction limit, that is, ne===in the same equation, the wavelength of artificial illumination light,, I and O are the refractive index and half angle aperture of the object space, respectively.
Since the 1980s, with the advancement of science and technology towards small-scale and low dimensional spaces, as well as the development of scanning probe microscopy technology, a new discipline has emerged in the field of optics - near-field optics. Near field optics refers to the optical phenomenon where the distance between the photodetector and the sample is less than the radiation wavelength; The near-field optical microscope is a new type of ultra-high spatial resolution optical instrument based on the theory of near-field optics. In 1984, the invention of the prototype of the near-field optical microscope, the "optical stethoscope," marked the first breakthrough in the diffraction limit resolution of optical microscopes by humans. Since 1992, when single-mode optical fibers were used to make optical probes and shear forces were used to measure the distance from the probe tip to the sample surface, near-field optical microscopes have been used as a new type of optical instrument for observing and studying the appearance, morphology, and intrinsic properties of subwavelength objects. In the following few years, it was widely applied in fields such as physics, chemistry, biology, medicine, and information at the nanoscale and mesoscopic scales.
