Nanoscale optical tomography based on volume-scanning near-field microscopy

• US 7,978,343 B2
• Filed: 03/17/2009
• Issued: 07/12/2011
• Est. Priority Date: 03/21/2008
• Status: Active Grant

• Current Assignee: Board of Trustees of The University of Illinois
• Original Assignee: Board of Trustees of The University of Illinois
• Inventors: Hillenbrand, Rainer, Sun, Jin, Schotland, John C., Carney, Paul Scott
• Primary Examiner(s): Pham; Hoa Q
• Application Number:
  US12/405,449
• Publication Number:
  US 20100039654A1
• Time in Patent Office: 847 Days
• Field of Search: 356601-623, 356/237.1, 356/337, 356445-448, 382/154
• US Class Current: 356/601
• CPC Class Codes: G01Q 60/22 Probes, their manufacture, or their related instrumentation, e.g. holders

Abstract

An apparatus and methods for nanoscale optical tomography based on back-scattering mode near-field scanning optical microscopy with a volumetric scan of the probe. The back-scattered data collected by a volumetric scan of the probe contains three-dimensional structural information of the sample, which enables reconstruction of the dielectric sample without other mechanical movements of the instrument.

Claims

1. An apparatus for imaging an object characterized by a surface, the apparatus comprising:

a. a light source for illuminating the object with an illuminating electromagnetic wave via an illumination path;

b. a detector for detecting electromagnetic waves scattered by the object via a collection path, and for generating a detector signal,

c. an aperture, disposed within at least one of the illuminating path and the collection path, wherein the aperture is characterized by a dimension equal to, or smaller than, a characteristic wavelenth of the illuminating electromagnetic wave;

d. a scanner for scanning a relative position of the aperture with respect to the object to a plurality of relative positions, not all of which relative positions are coplanar, above the surface of the object; and

e. a controller adapted

i. to apply a forward model of a point scatterer in a manner as to derive a three dimensional scattering model;

ii. to receive the detector signal and generate a detected data function; and

iii. to invert the detected data function in terms of the forward model to obtain a three-dimensional reconstruction of the object.

2. An apparatus in accordance with claim 1, wherein the aperture is disposed in the illumination path.

3. An apparatus in accordance with claim 1, wherein the aperture is a probe tip.

4. An apparatus in accordance with claim 1, wherein a single aperture lies in both the illumination and the collection path.

5. An apparatus in accordance with claim 1, wherein the light source is tunable in wavelength.

6. A method for imaging an object characterized by a surface, the method comprising:

a. illuminating the object with an illuminating electromagnetic wave via an illumination path;

b. detecting, with a detector disposed in a far field, electromagnetic waves scattered by the object via a collection path,

wherein an aperture, disposed within at least one of the illumination path and the collection path, is equal to, or smaller than, a characteristic wavelength of the electromagnetic wave;

c. scanning a relative position of the aperture with respect to the object to a plurality of positions, not all of which positions are coplanar, above the surface of the object;

d. applying a forward model of a point scatterer in a manner as to derive a three dimensional scattering model; and

e. inverting a detected data function in terms of the forward model to obtain a three-dimensional reconstruction of the object.

7. A method in accordance with claim 6, wherein the step of scanning the aperture includes scanning a position of a probe tip that is small on a scale of the characterizing wavelength of the illuminating electromagnetic wave.

8. A method in accordance with claim 6, wherein the forward model is expressed in terms of a block-diagonalized forward integral equation.