Near-field microscope, scanning near-field microscope
microscope that measures the intensity of electromagnetic or supersonic radiation through a nanometre-sized waveguide extremely close to the specimen while scanning the waveguide in a raster pattern to obtain high resolution images.
With ordinary microscopes, the resolution is limited to half of the wavelength
of the electromagnetic waves or sonic waves used for observation. However,
the resolution can be increased by making the aperture angle wide. If observation
is made extremely close to the specimen through a nanometre-sized waveguide
while moving the waveguide in a raster pattern, the resolution of the image
is determined not by the wavelength but by the diameter of the waveguide
alone. The near-field microscope obtains an image on the basis of this
principle. However, the reduction in the diameter of the waveguide weakens
the signal intensity, and so highly sensitive receivers are required to
achieve a better resolution. The near-field supersonic microscope, laser
scanning microscope, and fluorescent microscope are being developed.