University of Illinois

Brynmor J Davis

Paul Scott Carney

Stephen A Boppart

Daniel L Marks

John Carl Schotland

Kimani C Toussaint

Jin Sun

Santosh Tripathi

A coherent confocal microscope and methods for measuring elements of the non-linear susceptibility of a nanoparticle, including, more particularly, all of the elements of the second-order susceptibility tensor of a single nanoparticle under permutation and Kleinman symmetry. Using a high numerical aperture lens, two-dimensional scanning and a vector beam shaper, the second-order nonlinear susceptibility is derived from a single confocal image. A forward model for the problem is presented and a computationally efficient data processing method robustly solves the inverse problem.

Second-order nonlinear susceptibility of a nanoparticle using coherent confocal microscopy

A method and computer program product for imaging an object are disclosed. The object is illuminated with an electromagnetic wave, characterized by a spectrum of illuminating wavevectors. Electromagnetic waves scattered by the object are detected, and are characterized by a spectrum of detected wavevectors. An aperture equal to or smaller than an instantaneous characterizing wavelength of the illuminating electromagnetic wave is disposed between the source and the detector. At least one of the illuminating and detected wavevectors is varied in magnitude to provide information regarding a scattering characteristic of the object. By applying a forward model of the aperture to derive a three-dimensional scattering model, a three-dimensional reconstruction of the object may be obtained by inverting a detected data function in terms of the forward model.

Spectral near-field optical tomography

A coherent confocal microscope for fully characterizing the elastic scattering properties of a nanoparticle as a function of wavelength. Using a high numerical aperture lens, two-dimensional scanning and a simple vector beam shaper, the rank-2 polarizability tensor is estimated from a single confocal image. A computationally efficient data processing method is described and numerical simulations show that this algorithm is robust to noise and uncertainty in the focal plane position. The measurement of the polarizability removes the need for a priori assumptions regarding the nanoparticle shape.

Robust determination of the anisotropic polarizability of nanoparticles using coherent confocal microscopy

Methods and apparatus for three-dimensional imaging of a sample. A source is provided of a beam of light characterized by partial spatial coherence. The beam is focused onto a sample and scattered light from the sample is superposed with a reference beam derived from the source onto a focal plane detector array to provide an interference signal. A forward scattering model is derived relating measurement data to structure of an object to allow solutions of an inverse scattering problem, based upon the interference signal so that a three-dimensional structure of the same may be inferred. The partial spatial coherence of the source, which may be fixed or variable, may advantageously provide for rejection of multiple scattering artifacts and thus improve image quality.

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Champaign, IL, United States of America

Brynmor J Davis