Method and apparatus for near-field, scanning, optical microscopy by reflective, optical feedback
First Claim
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1. Apparatus for collecting information from a surface of a sample, comprising:
- a) a light source that comprises a first optical cavity, and that further comprises an emissive face portion for emitting therethrough radiation from the first optical cavity;
b) means for situating the emissive face portion near the sample surface such that the optical cavity is reflectively coupled to a spot on the sample surface, relative to at least one wavelength λ
of radiation emitted from the optical cavity;
c) means for scanning the spot over a portion of the sample surface; and
d) means for detecting changes in an output characteristic of the light source,CHARACTERIZED IN THAT;
e) the emissive face portion has a maximum extent L in at least one dimension parallel to the sample surface that is less than λ
; and
f) the situating means, in use, to situate the emissive face portion at a distance from the sample surface that is less than or approximately equal to L.
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Abstract
Apparatus and methods of near-field scanning optical microscopy (NSOM) are described. A sensing technique is used, in which a light source having an optical cavity is reflectively coupled to the sample surface. Changes in the surface properties of the sample at the sensed location alter the optical feedback in the light source. This leads to detectable changes in the output characteristics of the light source.
86 Citations
22 Claims
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1. Apparatus for collecting information from a surface of a sample, comprising:
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a) a light source that comprises a first optical cavity, and that further comprises an emissive face portion for emitting therethrough radiation from the first optical cavity; b) means for situating the emissive face portion near the sample surface such that the optical cavity is reflectively coupled to a spot on the sample surface, relative to at least one wavelength λ
of radiation emitted from the optical cavity;c) means for scanning the spot over a portion of the sample surface; and d) means for detecting changes in an output characteristic of the light source, CHARACTERIZED IN THAT; e) the emissive face portion has a maximum extent L in at least one dimension parallel to the sample surface that is less than λ
; andf) the situating means, in use, to situate the emissive face portion at a distance from the sample surface that is less than or approximately equal to L. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method for collecting information from a surface of a sample, comprising:
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a) operating a light source having an optical cavity such that electromagnetic radiation is present in the optical cavity, and a portion of the radiation in the optical cavity is emitted through an emissive face portion; b) during (a), situating the emissive face portion near the sample surface such that the optical cavity is reflectively coupled to a spot on the sample surface, relative to at least one wavelength λ
of radiation emitted by the light source;c) during (b), scanning the spot over a portion of the sample surface; and d) during (c), detecting changes in an output characteristic of the light source. CHARACTERIZED IN THAT step (b) is carried out such that; e) the spot has a maximum extent L in at least one dimension parallel to the sample surface that is less than λ
; and
`f) the emissive face portion is situated at a distance from the sample surface that is less than or approximately equal to L. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22)
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Specification