Resolution Of Near-field Optical Microscopy Research Articles

Contact scanning near-field optical microscopy

A new method of scanning in near-field optical microscopy, which makes it possible to operate in contact with the experimental sample, is proposed and implemented. This method permits the practical utilization of the idea of using the dipole-dipole resonance transfer of excitation energy from the active element of the microscope to the sample for achieving a fundamental improvement in the resolution of near-field optical microscopy.

Topographical artifacts and optical resolution in near-field optical microscopy

Starting from general principles of near-field optical microscopy, I demonstrate that an optical image obtained with any near-field microscope operating in a constant (probe–surface) distance mode contains pure topographical artifacts, topographically induced features, and pure optical contrast. Scanning a sharp topographical step at an otherwise homogeneous sample surface is shown to provide a sensitivity window that determines the scale on which the near-field optical image would represent mostly pure optical contrast. I suggest that the sensitivity window can be regarded as the upper limit of optical resolution of a near-field microscope.

What Do we Really See? Resolution in Near-Field Optical Microscopy

Abstract Six years ago there was a symposium held at the 1991 EMS A meeting to discuss the issue of “Resolution in the Microscope”.1 In this paper, we will look at resolution in near-field imaging, a blossoming field, and see whether any of our concepts have changed. It has been only within the last decade that the concept of super-resolution microscopy in the near field has been vigorously pursued and experimentally demonstrated. (For reviews on the subject, the reader is referred to the proceedings of the second and third international conferences on near field optics.) However, as in most areas of microscopy, the idea is not new, but rather rediscovered after decades of dormancy. The idea of optical resolution unhindered by far-field diffraction limitations was conceived more than a half-century ago by E.H. Synge4 in a paper entitled “A Suggested Method for Extending Microscopy Resolution into the Ultra-Microscope Regime”.

Resolution in near-field optical microscopy

A discussion of the relationship between the spatial resolution in near-field and far-field microscopy is presented in the context of linear optical transfer function theory. The results of a simplified theory of near-field optical beam formation are compared with experimental measurements of the near-field probe profile using visible light and subwavelength probes. The radial intensity profile of a near-field light beam is shown to be describable to a first approximation by a simple Gaussian function.

Resolution in near-field optical microscopy

It has only been within the last half decade that the concept of super resolution microscopy in the near-field has been vigorously pursued and experimentally demonstrated. However, the idea of optical resolution unhindered by far field diffraction limitations was conceived more than a half century ago by Synge and further elaborated by O'Keefe in the fifties. That die method was possible, however, was only first demonstrated using 3cm wavelength microwaves almost 20 years later.The basic principles of the method of near field scanning optical microscopy (NSOM) have been described before in the literature. Briefly, the idea is as follows: if an optical probe (source or detector) of diameter D is positioned within a distance of approximately D/π from the surface of an object, and the reflected, transmitted or emitted light is detected, then the lateral spatial region from which the information occurs is limited to aregion of approximate size D and not by the wavelength of the illuminated or detected light.