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Projects
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ISAM is a method of computed imaging that takes advantage to the instrumentation developed in the low-coherence interferometry and Optical coherence tomography communities. In scanned-beam ISAM a sample is illuminated with a beam and the backscattered light is detected interferometrically.
The beam is scanned over a plane and the combined data set is used to reconstruct the dielectric susceptibility of the object in 3-D.
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Synthetic optical holography (SOH) is a new holographic modality for phase imaging in scanning optical microscopy. It uniquely combines high-speed phase imaging, technical simplicity and simultaneous operation at visible to THz frequencies. All of these benefits can be obtained by the simplest implementation imaginable: only a linearly moving reference mirror needs to be added to the microscope setup. SOH has been implemented in scanning near-field microscopy (s-SNOM), speeding-up the image acquisition process by a factor of 50 in comparison to standard technology and thus turning s-SNOM in a rapid screening tool for the nanooptical inspection of surfaces.
In confocal microscopy, SOH enables static and dynamic optical surface profiling of biological specimen and micromechanical systems, and can in principle be combined with fluorescence and Raman imaging. Our research aims at exploring new (bio)imaging applications based on SOH and the development of new holographic encoding and reconstruction schemes.
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The theoretical description of the statistical nature of light generated in fast pulse laser systems has lagged far behind the experimental data collected for such systems. The state of the art for fast pulse generation cannot be modeled within the standard framework of statistically stationary
optical fields. Using a cyclostationary model to describe the pulsed, optical fields, we investigate propagation-induced effects for pulsed fields, including changes in the spectrum and state of polarization far from the source. We also investigate novel methods of collecting data to gain access
to the underlying cyclostationary statistics of the fields.
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Near-field Scanning Optical Tomography (NSOT) explores the extension of imaging modalities such as Photon Scanning Tunneling Microscopy (PSTM) and
Near-field Scanning Optical Microscopy (NSOM) to samples that contains three-dimensional structure or when the probe tip is not scanned in
grazing proximity to the sample. We solve the linearized inverse scattering problem to produce sub-wavelength resolved tomographs of the
object under said conditions.
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A Photon Scanning Tunneling Microscope (PSTM) is a device where the object is illuminated by an evanescent wave generated at the face of a prism or
slide and the field is detected via a fiber probe in the near-zone of the sample (as in NSOM). The data obtained with a PSTM is not amenable
to direct interpretation but we show sufficient information exits in
the raw data to numerically compute the two-dimensional structure of a thin sample, thus achieving a computational lens for the near-field.
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The propagation of correlation functions for optical fields is a more computationally expensive operation than propagating the fields themselves. Using a coherent mode decomposition (CMD) of the cross-spectral density (CSD) of a random field, we investigate the propagation of fields that are well-approximated
as geometrical fields, either scalar or electromagnetic. The correlation functions for the propagated fields are found, as are important physical quantites - the time-averaged intensity and the degree of polarization. We are also investigating the use of a geometrical model for the fields in certain imaging
modalities, and other methods for improving the computation of the CSD for propagated fields.
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Coupled mode theory is useful for predicting the coupling and field-sharing behavior of laser arrays. We solve for the second-order correlation functions in coupled mode theory using stochastic sources or boundary conditions to predict partially coherent operation in laser arrays.
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