Purdue Research Foundation

Garth Jason Simpson

Changqin Ding

Ryan Douglas Muir

Chen Li

Fengyuan Deng

David Joseph Kissick

Justin Allen Newman

James Ulcickas

Shane Zachary Sullivan

Charles Addison Bouman

Mark Carlsen

Suhas Sreehari

Andreas C Geiger

Nicholas Roman Pogranichniy

Lynne S Taylor

Jeremy Madden

Duangporn Wanapun

Umesh S Kestur

Scott J Toth

Ronald D Wampler

Ryan M Plocinik

Paul David Schmitt

Mark Polizzi

Casey Smith

Alex Sherman

Nicole Mulready Scarborough

Minghe Li

Aleksandr Razumtcev

Ellen J Gualtieri

A method of selectively photothermally heating a sample in a fluorescence-detected mid-infrared photothermal microscopy is disclosed which includes energizing a sample with one or more modulated infrared (IR) beams sourced by a multichannel laser array, concurrently continuously illuminating the sample with a probe beam, thereby generating a fluorescence response signal, capturing the fluorescence response signal, processing the captured modulated fluorescence response signal into two IR absorption spectra corresponding to chemical properties of two components in the sample by scanning over each channel of the multichannel laser array, generating a binary mask associated with the two spectra, establishing a cost function based on the generated binary mask, optimizing the cost function by optimizing the binary mask, and selectively energizing channels of the multichannel laser array based on the optimized binary mask thereby maximizing discrimination between the two components.

Fluorescence-detected mid-infrared photothermal microscopy

Methods for measuring diffusion in a medium. One method includes dissolving a fluorescent sample in a medium, imaging the fluorescent sample with a patterned illumination Fluorescence Recovery After Photobleaching (FRAP) technique, and analyzing a set of microscope images of the photobleached dissolved fluorescent sample with the patterned illumination using a Fourier Transform (FT) FRAP technique.

Method of measuring diffusion in a medium

A method for inducing a covert misclassification performed on a non-transitory computer readable medium, the method includes identifying a target position. The method further includes creating a spectral perturbation tensor. The spectral perturbation tensor is configured to shift a projection of an initial spectrum towards the target position. Additionally, the method includes combining the spectral perturbation tensor to the initial spectrum. Further, the method includes classifying the combination of the spectral perturbation tensor and the initial spectrum with an established classifier, thereby designing the spectral perturbation tensor such that the combination is misclassified.

Methods for inducing a covert misclassification

A method for phase contrasting-correlation spectroscopy: converting an incident linearly polarized light into two polarized components (polarized divergent and convergent components, wherein the polarized divergent component is orthogonal to the polarized convergent component), focusing each of the polarized divergent component and the polarized convergent component into a focal plane, thereby producing two focus planes constituting a reference focus (RF) plane and a sample focus (SF) plane; placing a sample at the SF plane and ambient conditions of the sample at the RF plane, resulting in a phase shift between the two polarized components; reconstituting the two phase-shifted polarized components into a phase-shifted linearly polarized light; detecting the phase-shifted linearly polarized light; calculating phase and intensity of the sample from the phase-shifted linearly polarized light; establishing an autocorrelation of phase and intensity of the phase-shifted linearly polarized light; and generating correlograms of intensity and phase of the phase-shifted linearly polarized light.

Method and system for axially-offset differential interference contrast correlation spectroscopy

A method of obtaining a measurement signal representative of the particle size distributions in nanocrystal suspensions that includes a step of providing a first light beam along a first axis to a first micro-retarder array to generate polarization wavefront shaped light. The shaped light is applied to an objective configured to focus two orthogonally polarized components of the polarization wavefront shaped light to produce first and second axially offset foci along the first axis. A sample having particles in suspension is disposed in one foci to produce a measurement optical signal having phase and intensity values corresponding to at least some of the particles in suspension. The method also includes determining intensity and quantitative phase information as a function of time based on the optical signals.

Axially-offset differential interference contrast correlation spectroscopy

A method for imaging a sample, wherein the sample changes a polarization state of light as a function of position, wherein the method includes changing a polarization state of a purely polarized light of an incident light striking a micro-retarder array, thereby inducing a changed polarization state of the polarization state. The micro-retarder array is placed in a rear conjugate focal plane of a microscope. The method additionally includes projecting the changed polarization state of the polarization state into an object plane of the microscope containing the sample.

Systems and methods for imaging a sample

A system including a first micro-retarder array, wherein the first micro-retarder array is configured to convert a purely polarized light of an incident light into two components. The system additionally includes an optical device, wherein the optical device is configured to collimate the two components to two foci planes. Moreover, the system includes a second micro-retarder array, wherein the second micro-retarder array is configured to combine a set of two components of the incident light, thereby producing a second purely polarized light. Further the system includes a detector, wherein the detector is configured to receive the second purely polarized light.

Method of phase contrasting

A quantitative optical microscopy arrangement is described. Specifically, a digital filter derived from linear discriminant analysis is described for recovering impulse responses in applications that may include photon counting from a high speed photodetector and applied to remove ringing distortions from impedance mismatch in multiphoton fluorescence microscopy. Training of the digital filter is achieved by defining temporally coincident and non-coincident transients and identifying the projection within filter-space that best separates the two classes. The training allows rapid data analysis by digital filtering. The LDA filter is also capable of recovering deconvolved impulses for single photon counting from highly distorted ringing waveforms from an impedance mismatched photomultiplier tube. The LDA filter is also successful in removing these ringing distortions from two-photon excited fluorescence micrographs and may extend the dynamic range of photon counting by about three orders of magnitude through minimization of detector paralysis.

Deconvolution by digital filtering from linear discriminate analysis

A beam-scanning optical design is described for achieving up to kHz frame-rate optical imaging on multiple simultaneous data acquisition channels. In one embodiment, two fast-scan resonant mirrors direct the optical beam on a circuitous trajectory through the field of view, with the trajectory repeat-time given by the least common multiplier of the mirror periods. Dicing the raw time-domain data into sub-trajectories combined with model-based image reconstruction (MBIR) 3D in-painting algorithms allows for effective frame-rates much higher than the repeat time of the Lissajous trajectory. Because sub-trajectory and full-trajectory imaging are different methods of analyzing the same data, both high-frame rate images with relatively low resolution and low frame rate images with high resolution are simultaneously acquired.

High frame-rate multichannel beam-scanning microscopy

A method for quantifying crystallinity within a sample using second harmonic generation microscopy is described herein. In one aspect, a method for reducing the timeframe for accelerated stability testing of amorphous solid dispersions of active pharmaceutical ingredients though identifying regions of interest to quantify crystallinity and composition is presented herein.

Characterization of trace crystallinity by second harmonic generation microscopy

A method and apparatus for photon, ion or particle counting described that provides seven orders of magnitude of linear dynamic range (LDR) for a single detector. By explicitly considering the log-normal probability distribution in voltage transients as a function of the number of photons, ions or particles present, the binomial distribution of observed counts for a given threshold, the mean number of photons, ions or particles can be determined well beyond the conventional limit.

System and method of extending the linear dynamic range of event counting

The present disclosure provides a system and method for efficiently mining multi-threshold measurements acquired using photon counting pixel-array detectors for spectral imaging and diffraction analyses. Images of X-ray intensity as a function of X-ray energy were recorded on a 6 megapixel X-ray photon counting array detector through linear fitting of the measured counts recorded as a function of counting threshold. An analytical model is disclosed for describing the probability density of detected voltage, utilizing fractional photon counting to account for edge/corner effects from voltage plumes that spread across multiple pixels. Three-parameter fits to the model were independently performed for each pixel in the array for X-ray scattering images acquired for 13.5 keV and 15.0 keV X-ray energies. From the established pixel responses, multi-threshold composite images produced from the sum of 13.5 keV and 15.0 keV data can be analytically separated to recover the monochromatic images through simple linear fitting.

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West Lafayette, IN, United States of America

Garth Jason Simpson