Introduction
Since 1928, British scientist-Edward Hutchinson Synge proposed the design concept of near-field optical microscope in order to improve the resolution of traditional optical microscopes. Scientists have been committed to reducing the diameter and Control the distance between the sample and the small hole to try to obtain better near-field optical images and information (as shown in the overview picture on the right).
Progress
The continuous advancement of modern science and technology, including micro-nano processing technology and scanning probe microscopy technology, has greatly promoted the development of near-field optical microscopes, and various feedbacks have appeared Forms and working methods of near-field optical microscopes (reflective, transmissive, multi-probe, etc.). At present, the near-field optical microscope recognized by the academia is based on scanning probe microscopy technology. A fiber probe with a small aperture is attached to a tuning fork. The tuning fork is used to sense the distance between the sample and the probe, and the distance is measured. The control can meet the two requirements of the near-field optical microscope: small hole and macro.
However, the resolution of near-field optical images obtained by the above methods is more difficult to break through the diffraction limit of light. The better resolution obtained is generally a few hundred nanometers. How can the resolution be further improved? It has also become the direction that scientists have been working hard.
Since 1984, scientists (see the article Phil.Trans.R.Soc.Lond.A(2004)362,787–805) have proposed metalized AFM probes and obtained the The near-field optical image with a resolution of ~10nm or better has promoted research in the field of near-field optics. The general principle is shown in Figure 1 on the right.