The operational principle behind near-field optical imaging involves illuminating a specimen through a sub-wavelength sized aperture whilst keeping the specimen within the near-field regime of the source. Broadly speaking, if the aperture-specimen separation is kept roughly less than half the diameter of the aperture, the source does not have the opportunity to diffract before it interacts with the sample and the resolution of the system is determined by the aperture diameter as oppose to the wavelength of light used. An image is built up by raster-scanning the aperture across the sample and recording the optical response of the specimen through a conventional far-field microscope objective. (As opposed to conventional optical microscopy or 'far-field optical microscopy').

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Scanning near field optical microscopy

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A scanning probe microscope where light is used to obtain local information about topography and optical properties. In conventional light microscopy the resolution is limited approximately to the half of the wavelength of the incident light. In order to circumvent this restriction the optical nearfield (or evanescent field) is used in combination with a nanosized light source (e.g. A tapering fibre).

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A method for observing local optical properties of a surface that can be smaller than the wavelength of the light used. [NTN]

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The operational principle behind near-field optical imaging involves illuminating a specimen through a sub-wavelength sized aperture whilst keeping the specimen within the near-field regime of the source. Broadly speaking, if the aperture-specimen separation is kept roughly less than half the diameter of the aperture, the source does not have the opportunity to diffract before it interacts with the sample and the resolution of the system is determined by the aperture diameter as oppose to the wavelength of light used. An image is built up by raster-scanning the aperture across the sample and recording the optical response of the specimen through a conventional far-field microscope objective. (As opposed to conventional optical microscopy or 'far-field optical microscopy').

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Scanning near field optical microscopy

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A method for observing local optical properties of a surface that can be smaller than the wavelength of the light used. [NTN]

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A type of scanning probe microscopy that maps the near-field optical properties of an interface.

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