Abstract: A scanning imaging method includes splitting an optical beam into a reference beam and a scanning beam, generating an interference map, and processing the interference map to produce a reconstructed image of a sample. Generating the interference map includes, for each of a plurality of sections of the sample, generating a respective interference-map element of the interference map by: (i) illuminating the section with the scanning beam to generate a plurality of scattered beams, each scattered beam corresponding to a respective spatial frequency of the scanning beam, (ii) attenuating the reference beam, (iii) generating a plurality of interference signals at least in part by interferometrically combining the plurality of scattered beams and the attenuated reference beam while modulating a phase difference between the reference beam and the plurality of scattered beams, and (iv) detecting the plurality of interference signals to yield the respective interference-map element.

Abstract: Methods and apparatus are provided for imaging a response of a sample to radiative heating. A method in accordance with one embodiment has steps of: illuminating a first area of the sample with a radiative heating beam; illuminating a portion of the first area with a probe beam; collecting light exiting the sample due to interaction of the probe beam with the sample; superimposing the light exiting the sample with a reference beam derived from the probe beam, wherein the reference is characterized by an optical phase relative to the probe beam; detecting a spatial portion of the light exiting the sample and the reference beam with at least one detector to generate an interference signal; and processing the interference signal to obtain an image of the sample associated with absorption of the radiative heating beam.

Abstract: An intraoperative probe and a system for optically imaging a surgically significant volume of tissue or other scattering medium. An illumination source generates an illuminating beam that is conveyed to the vicinity of the tissue and a beam splitter, that may be no more than an optical phase reference, splits the illuminating beam into a sample beam along a sample beam path and a reference beam along a reference beam path. A scanning mechanism scans a portion of the sample beam across a section of the scattering medium, while a detector detects return beams from both the reference beam path and the sample beam path and generates an interference signal. A processor computationally moves an effective focus of the sample beam without physical variation of focus of the sample beam. The probe may have a sterilizable fairing that may be detachable.

Abstract: Methods and apparatus are provided for imaging a response of a sample to radiative heating. A method in accordance with one embodiment has steps of: illuminating a first area of the sample with a radiative heating beam; illuminating a portion of the first area with a probe beam; collecting light exiting the sample due to interaction of the probe beam with the sample; superimposing the light exiting the sample with a reference beam derived from the probe beam, wherein the reference is characterized by an optical phase relative to the probe beam; detecting a spatial portion of the light exiting the sample and the reference beam with at least one detector to generate an interference signal; and processing the interference signal to obtain an image of the sample associated with absorption of the radiative heating beam.

Abstract: Methods and apparatus for assessing and correcting phase variations and motion artifacts in a coherent tomogram of a sample. Coherent techniques are used scan a broadband optical beam across a sample in a specified scan pattern and to acquire a cube of complex data constituting a full tomogram. Generalized motion of the sample is then quantified based at least on a phase variation measured during the course of scanning the broadband optical beam in the specified scan pattern. Generalized motion includes both actual motion and apparent motion due to organized variation of some physical parameter such as temperature. Intensity structure of speckle imaged during the course of coherently acquiring the full tomograpm may be used to correct for motion of the sample in a plane transverse to a depth axis along the incident beam.

Abstract: Methods and apparatus for assessing and correcting phase variations and motion artifacts in a coherent tomogram of a sample. Coherent techniques are used scan a broadband optical beam across a sample in a specified scan pattern and to acquire a cube of complex data constituting a full tomogram. Generalized motion of the sample is then quantified based at least on a phase variation measured during the course of scanning the broadband optical beam in the specified scan pattern. Generalized motion includes both actual motion and apparent motion due to organized variation of some physical parameter such as temperature. Intensity structure of speckle imaged during the course of coherently acquiring the full tomograpm may be used to correct for motion of the sample in a plane transverse to a depth axis along the incident beam.

Abstract: Methods for obtaining a tomographic phase image of a specimen, either in transmission or in scatter. A specimen is illuminated by a temporally incoherent source and light collected in transmission or scattering is used to generate a scattered phase image of the specimen in multiple axial planes. The scattered field is solved for in wavevector space, and a derived instrument function is deconvolved to obtain specimen susceptibility in wavevector space. The specimen susceptibility is transformed to obtain a three-dimensional phase tomogram of the specimen.

Abstract: Methods and apparatus for imaging a phase or amplitude that characterizes a scattered field emanating from a physical medium. A local probe is stepped to a plurality of successive probe positions and illuminated with an illuminating beam, while a specified phase function is imposed on a reference beam relative to the illuminating beam. A field associated with the scattered field is superimposed with the reference beam and the detection of both yields a detected signal which is recorded as a function of probe position in order to obtain a hologram. The holograph is transformed, filtered, and retransformed to generate an image. Alternatively, the illuminating beam may directly illuminate successive positions of the physical medium.

Abstract: Methods and apparatus for imaging a phase or amplitude that characterizes a scattered field emanating from a physical medium. A local probe is stepped to a plurality of successive probe positions and illuminated with an illuminating beam, while a specified phase function is imposed on a reference beam relative to the illuminating beam. A field associated with the scattered field is superimposed with the reference beam and the detection of both yields a detected signal which is recorded as a function of probe position in order to obtain a hologram. The holograph is transformed, filtered, and retransformed to generate an image. Alternatively, the illuminating beam may directly illuminate successive positions of the physical medium.

Abstract: Methods for obtaining a tomographic phase image of a specimen, either in transmission or in scatter. A specimen is illuminated by a temporally incoherent source and light collected in transmission or scattering is used to generate a scattered phase image of the specimen in multiple axial planes. The scattered field is solved for in wavevector space, and a derived instrument function is deconvolved to obtain specimen susceptibility in wavevector space. The specimen susceptibility is transformed to obtain a three-dimensional phase tomogram of the specimen.

Abstract: Methods for correcting for aberrations in the image or three-dimensional reconstruction of a sampled region obtained by broadband interferometry. The sampled region is illuminated with a broadband beam of light, and light returned from the sample is detected, along with a reference beam, in order to derive an interference signal for pixels of a volume spanned by wavenumber and axes transverse to the beam propagation direction. An optimization procedure is performed with respect to a specified criterion so as to obtain an aberration-corrected image of at least one plane of the sampled region, either in a plane-specific manner or in a space-invariant manner throughout the sampled region. A filter function, which may be derived from the interference signal attendant to irradiating a sparsely distributed plurality of point scatterers, or otherwise, corrects for a detected aberrated point spread function.

Abstract: Methods for correcting for aberrations in the image or three-dimensional reconstruction of a sampled region obtained by broadband interferometry. The sampled region is illuminated with a broadband beam of light, and light returned from the sample is detected, along with a reference beam, in order to derive an interference signal for pixels of a volume spanned by wavenumber and axes transverse to the beam propagation direction. An optimization procedure is performed with respect to a specified criterion so as to obtain an aberration-corrected image of at least one plane of the sampled region, either in a plane-specific manner or in a space-invariant manner throughout the sampled region. A filter function, which may be derived from the interference signal attendant to irradiating a sparsely distributed plurality of point scatterers, or otherwise, corrects for a detected aberrated point spread function.

Abstract: An intraoperative probe and a system for optically imaging a surgically significant volume of tissue or other scattering medium. An illumination source generates an illuminating beam that is conveyed to the vicinity of the tissue and a beam splitter, that may be no more than an optical phase reference, splits the illuminating beam into a sample beam along a sample beam path and a reference beam along a reference beam path. A scanning mechanism scans a portion of the sample beam across a section of the scattering medium, while a detector detects return beams from both the reference beam path and the sample beam path and generates an interference signal. A processor computationally moves an effective focus of the sample beam without physical variation of focus of the sample beam. The probe may have a sterilizable fairing that may be detachable.

Abstract: Methods and computer program products for super-resolution mapping of nanoprobes having spectrally distinguishable coherent scattering properties. A sample containing a plurality of nanoprobes is illuminated with broadband light, and coherent scattering by the nanoprobes is detected. Scattered light is spectrally associated with respective nanoprobes, allowing a position associated with each nanoprobe to be mapped.

Abstract: 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.

Abstract: Methods and a non-transient computer medium embodying computer readable code for extracting bulk spectroscopic properties of a particle. A forward model is built of an optical field focused on, and interacting with, the particle, where the forward model parameterized in terms of at least one geometrical characteristic of the particle. The particle, which may be a filamentary material, is illuminated with an incident optical field having a spectral range. Either a transmitted or scattered optical field is detected in a far-field zone as a function of wavenumber to obtain a measured spectrum. The measured spectrum is inverted to recover the imaginary part of the complex refractive index of the particle.

Abstract: 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.

Abstract: 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.

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.

Abstract: A near-field microscope using one or more diffractive elements placed in the near-field of an object to be imaged. A diffractive covers the entire object, thus signal may thereby be gathered from the entire object, and advantageously increase the signal-to-noise ratio of the resulting image, as well as greatly improve the acquisition speed. Near-field microscopy overcomes the limitation of conventional microscopy in that subwavelength and nanometer-scale features can be imaged and measured without contact.