Ann Arbor, MI, United States
Ann Arbor, MI, United States

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Demers J.-L.H.,Dartmouth College | Esmonde-White F.W.,University of Michigan | Esmonde-White F.W.,Kaiser Optical Systems Inc. | Esmonde-White K.A.,University of Michigan | And 2 more authors.
Biomedical Optics Express | Year: 2015

Combining diffuse optical tomography methods with Raman spectroscopy of tissue provides the ability for in vivo measurements of chemical and molecular characteristics, which have the potential for being useful in diagnostic imaging. In this study a system for Raman tomography was developed and tested. A third generation microCT coupled system was developed to combine 10 detection fibers and 5 excitation fibers with laser line filtering and a Cytop reference signal. Phantom measurements of hydroxyapatite concentrations from 50 to 300 mg/ml had a linear response. Fiber placement and experiment design was optimized using cadaver animals with live animal measurements acquired to validate the systems capabilities. Promising results from the initial animal experiments presented here, pave the way for a study of longitudinal measurements during fracture healing and the scaling of the Raman tomography system towards human measurements. © 2015 Optical Society of America.


Taquet N.,University of Lorraine | Pironon J.,University of Lorraine | De Donato P.,University of Lorraine | Lucas H.,Kaiser Optical Systems Inc. | Barres O.,University of Lorraine
International Journal of Greenhouse Gas Control | Year: 2013

This study reports the ability of the coupled Raman-FTIR/completion system to establish continuous measurements of soil gases for the monitoring of the CO2 sequestration sites. The method was deployed in the first French CCS pilot at Lacq-Rousse, in France during the injection operation. In this study, the continuous recording of the N2, O2, H2O and CO2 concentrations in soil allowed by the coupled Raman/FTIR completion system appears as a first step to decipher CO2 abnormal variations at the surface of the CCS site. © 2012 Elsevier Ltd.


Raw data inputs are treated as independent signal sources to reduce computational lag without adversely affecting signal-to-noise ratio (SNR). Applications include spectroscopy, multiple linear regression, mass balance quantitation and the calculation of physical properties. The input-specific averaging has been applied to Raman spectroscopy, where the inputs are averaged spectra from which peak heights or areas are obtained from integration. Alternatively, peak areas or heights can be obtained from unaveraged spectra and are then averaged before use in further calculations as inputs to produce a desired output. The output(s) are linear or nonlinear combinations of the peak heights or areas, coupled with weighting factors which relate the raw inputs to a quantitative output such as concentration of a chemical species. Each specific input can use a different type of averaging. The overall goal may be optimization for best precision, and/or optimization for minimum lag time.


Patent
Kaiser Optical Systems Inc. | Date: 2012-08-01

Raman signal amplification apparatus comprises an ellipsoidal reflector providing a first real focus f1, and second real or virtual focus f2, both foci being situated within a sample volume. When an input laser excitation beam having an initial numerical aperture (NA) is focused onto one of the foci, the beam is reflected by the reflector and refocused onto alternating foci, such that the NA of the reflected optical path progressively increases for higher efficiency collection of Raman emissions from the multiple foci. The ellipsoidal reflector may be a half section providing a single real focus f1, with a flat reflector producing a mirror image of the ellipsoidal reflector, such that f2 is a virtual focus occupying the same point as f1. Alternatively, the ellipsoidal reflector may have a first half section with a first real focus f1 and a second half section with a second real focus f2.


Patent
Kaiser Optical Systems Inc. | Date: 2011-05-27

A compact Raman analysis system combines a near-infrared (NIR) laser source, a 2D array collecting anti-Stokes Raman spectra, and a probe configured to measure complex solid samples, including pharmaceutical tablets and other large-area targets with reduced background fluorescence at relatively low cost. The system collects spectra from an area of 1-mm or greater, preferably 3-12 mm or more, facilitating the collection of statistically useful data from inhomogeneous and laser-sensitive samples, among other applications. Potential pharmaceutical applications include tablet dosage level measurements, as well as online and at-line quality-control (QC) monitoring opportunities. Other applications include tablet identification as a forensic tool to identify counterfeit pharmaceutical products; granulation and blend uniformity for improved formulation via better process understanding,


A monolithic optical element and system is used for collimating or focusing laser light from or to optical fibers. The optical fiber terminates in a tip that directly abuts against the first surface of the optical element. The optical element may provide a collimation or focusing function depending upon whether the abutting fiber delivers light for collimation or receives focused light from a collimated beam. The optical element may be a standard or modified barrel or drum lens, with the first and second surfaces being convex curved surfaces having the same or different radii of curvature. The end of the optical element to which the fiber abuts may have a diameter to match the inner diameter of a ferrule for positioning the fiber. A pair of the elements may be used for collimation and focusing in a Raman probehead or other optical detection system.


Methods and systems for spectrometer dark correction are described which achieve more stable baselines, especially towards the edges where intensity correction magnifies any non-zero results of dark subtraction, and changes in dark current due to changes in temperature of the camera window frame are typically more pronounced. The resulting induced curvature of the baseline makes quantitation difficult in these regions. Use of the invention may provide metrics for the identification of system failure states such as loss of camera vacuum seal, drift in the temperature stabilization, and light leaks. In system aspects of the invention, a processor receives signals from a light detector in the spectrometer and executes software programs to calculate spectral responses, sum or average results, and perform other operations necessary to carry out the disclosed methods. In most preferred embodiments, the light signals received from a sample are used for Raman analysis.


Methods and systems for spectrometer dark correction are described which achieve more stable baselines, especially towards the edges where intensity correction magnifies any non-zero results of dark subtraction, and changes in dark current due to changes in temperature of the camera window frame are typically more pronounced. The resulting induced curvature of the baseline makes quantitation difficult in these regions. Use of the invention may provide metrics for the identification of system failure states such as loss of camera vacuum seal, drift in the temperature stabilization, and light leaks. In system aspects of the invention, a processor receives signals from a light detector in the spectrometer and executes software programs to calculate spectral responses, sum or average results, and perform other operations necessary to carry out the disclosed methods. In most preferred embodiments, the light signals received from a sample are used for Raman analysis.


Patent
Kaiser Optical Systems Inc. | Date: 2013-05-28

Methods and apparatus facilitate dynamic range balancing for multi-component peaks of widely varying magnitude in an optical spectrometer. In a specific embodiment, filters attenuate the CH stretch region to produce a better fit of a multi-component hydrocarbon Raman spectrum to the dynamic range of a CCD detector. The filter may be translated into and out of the collimated collection beam to achieve a varying degree of attenuation. In certain applications, the filter is insertable into a collimated collection beam within a fiber-optic probe head to collect Raman spectra. The invention may include optical elements to create the collimated collection beam if not already present or not suitable for insertion of the filter. A second filter, an opaque or neutral density filter, may be insertable into the collimated collection beam to attenuate a broad spectral response within and outside the spectral range.


A material which is generally transparent in the visible region of the spectrum but reflective at laser wavelengths reduces undesirable, substrate-induced Raman and fluorescence scattering. A substrate provides a surface for supporting the sample, with the material being disposed between the surface of the substrate and the sample. The material is substantially transparent in the visible region of the spectrum but reflective at the laser wavelength, thereby minimizing unwanted Raman or fluorescence scattering that would be produced by the substrate if the material were not present. The substrate will typically be a glass microscope slide or multi-cell well plate. The optical filter material is preferably a multilayer dielectric filter acting as a hot mirror that reflects near-infrared energy. An advantage of visible transmission is that it allows back illumination from behind/underneath the slide or well plate, thereby being visible to a microscopes eyepiece or video camera. Methods and article are also disclosed.

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