A Raman chemical imaging system for detection of contaminants in food

2011 ◽  
Author(s):  
Kaunglin Chao ◽  
Jianwei Qin ◽  
Moon S. Kim ◽  
Chang Yeon Mo
Keyword(s):  
Imaging System ◽  
Chemical Imaging ◽  
Raman Chemical Imaging

Raman Chemical Imaging of Microcrystallinity in Silicon Semiconductor Devices

2001 ◽  
Vol 55 (3) ◽  
pp. 257-266 ◽  
Author(s):  
Michael D. Schaeberle ◽  
David D. Tuschel ◽  
Patrick J. Treado
Keyword(s):  
Integrated Circuits ◽  
Imaging System ◽  
Semiconductor Devices ◽  
Chemical Imaging ◽  
Tunable Filter ◽  
Resolving Power ◽  
High Definition ◽  
Semiconductor Wafer ◽  
Surface Distribution ◽  
Raman Chemical Imaging

Silicon integrated circuits are fabricated by the creation of complex layered structures. The complexity of these structures provides many opportunities for impurities, improperly annealed dopants, and stress effects to cause device contamination and failure. Nondestructive metrology techniques that rapidly and noninvasively screen for defects and relate silicon device structure to device performance are of value. We describe the first use of a liquid crystal tunable filter (LCTF) Raman chemical imaging microscope to assess the crystallinity of silicon semiconductor integrated circuits in a rapid and nondestructive manner without the need for sample preparation. The instrument has demonstrated lateral spatial resolving power of better than 250 nm and is equipped with a tunable imaging spectrometer having a spectral bandpass of 7.6 cm−1. The instrument rapidly produces high-definition Raman images where each image pixel contains a high-quality Raman spectrum. When combined with powerful processing strategies, the Raman chemical imaging system has demonstrated spectral resolving power of 0.03 cm−1 in a test silicon semiconductor wafer fabricated by using ion implantation. In addition, we have applied Raman chemical imaging for volumetric Raman imaging by analyzing the surface distribution of polycrystalline thin film structures. The approaches described here for the first time are generally applicable to the nondestructive metrology of silicon and compound semiconductor devices.

Quantitative Detection of Benzoyl Peroxide in Wheat Flour Using Line-Scan Macroscale Raman Chemical Imaging

2017 ◽  
Vol 71 (11) ◽  
pp. 2469-2476 ◽  
Author(s):  
Jianwei Qin ◽  
Moon S. Kim ◽  
Kuanglin Chao ◽  
Maria Gonzalez ◽  
Byoung-Kwan Cho
Keyword(s):  
Benzoyl Peroxide ◽  
Wheat Flour ◽  
Imaging System ◽  
Limit Of Detection ◽  
Chemical Imaging ◽  
Quantitative Detection ◽  
Imaging Method ◽  
Powdered Sample ◽  
Line Scan ◽  
Raman Chemical Imaging

A high-throughput Raman chemical imaging method was developed for direct inspection of benzoyl peroxide (BPO) mixed in wheat flour. A 5 W, 785 nm line laser (240 mm long and 1 mm wide) was used as a Raman excitation source in a push-broom Raman imaging system. Hyperspectral Raman images were collected in a wavenumber range of 103–2881 cm−1 from dry wheat flour mixed with BPO at eight concentrations (w/w) from 50 to 6400 ppm. A sample holder with a sampling volume of 150 × 100 × 2 mm3 was used to present a thin layer (2 mm thick) of the powdered sample for line-scan image acquisition with a spatial resolution of 0.2 mm. A baseline correction method based on adaptive iteratively reweighted penalized least squares was used to remove the fluctuating fluorescence signals from the wheat flour. To isolate BPO particles from the flour background, a simple thresholding method was applied to the single-band fluorescence-free images at a unique Raman peak wavenumber (i.e., 1001 cm−1) preselected for the BPO detection. Chemical images were created to detect and map the BPO particles. Limit of detection for the BPO was estimated in the order of 50 ppm, which is on the same level with regulatory standards. Pixel concentrations were calculated from the percentages of the BPO pixels in the chemical images. High correlation was found between the pixel concentrations and the mass concentrations of the BPO, indicating that the Raman chemical imaging method can be used for quantitative detection of the BPO mixed in the wheat flour.

Liquid Crystal Tunable Filter Raman Chemical Imaging

1996 ◽  
Vol 50 (6) ◽  
pp. 805-811 ◽  
Author(s):  
Hannah R. Morris ◽  
Clifford C. Hoyt ◽  
Peter Miller ◽  
Patrick J. Treado
Keyword(s):  
Liquid Crystal ◽  
Imaging System ◽  
Free Spectral Range ◽  
Chemical Imaging ◽  
Tunable Filter ◽  
Raman Imaging ◽  
Model Systems ◽  
High Definition ◽  
Product Model ◽  
Raman Chemical Imaging

A Lyot-type liquid crystal tunable filter (LCTF) suitable for high-definition Raman chemical imaging has been developed. The LCTF has been incorporated into an efficient Raman imaging system that provides significant performance advantages relative to any previous approach to Raman microscopy. The LCTF and associated optical path is physically compact, which accommodates integration of the LCTF within an infinity-corrected optical microscope. The LCTF simultaneously provides diffraction-limited spatial resolution and 7.6-cm-1 spectral bandpass across the full free spectral range of the imaging spectrometer. The LCTF Raman microscope successfully integrates, in a facile manner, the utility of optical microscopy and the analytical capabilities of Raman spectroscopy. In this paper the LCTF Raman imaging system is described in detail, as well as results of initial studies of polymer and corrosion product model systems.

Visualizing Molecular Species Within Inorganics: Raman Chemical Imaging of Minerals, Meteorites and Actinides

1997 ◽  
Vol 3 (S2) ◽  
pp. 859-860
Author(s):  
Nicole J. Kline ◽  
Mark C. Sparrow ◽  
Patrick J. Treado
Keyword(s):  
Imaging System ◽  
Optical Microscope ◽  
Chemical Imaging ◽  
Tunable Filter ◽  
Imaging Spectrometer ◽  
Composition And Structure ◽  
Inorganic Species ◽  
Raman Chemical Imaging ◽  
Mineral Components ◽  
Past Life

Raman chemical imaging microscopy is a powerful technique for the characterization of a wide host of materials, including inorganic species. The technique makes use of a liquid crystal tunable filter (LCTF) imaging spectrometer that is integrated within an infinity-corrected optical microscope. The imaging system provides the performance of a dispersive Raman spectrometer at every pixel of the charge-coupled device (CCD) detector used to capture the Raman image.We are currently applying Raman microscopy to the chemical imaging analysis of mineral composition and phase chemistry found in meteorites and terrestrial minerals. Determination of the chemical composition and structure of mineral components is often useful in developing an understanding of the petrologic process that formed the minerals, including those minerals that have been exposed to water. This is of particular interest in light of recent promising evidence of past life in Martian meteorites.

EXPRESS: Design Considerations for Discrete Frequency Infrared Microscopy Systems

2021 ◽  
pp. 000370282110133
Author(s):  
Rohit Bhargava ◽  
Yamuna Dilip Phal ◽  
Kevin Yeh
Keyword(s):  
Imaging System ◽  
Chemical Imaging ◽  
Optical Component ◽  
Imaging Systems ◽  
Imaging Data ◽  
Discrete Frequency ◽  
Figures Of Merit ◽  
Design Considerations ◽  
Hardware Implementations ◽  
Measurement Capabilities

Discrete frequency infrared (DFIR) chemical imaging is transforming the practice of microspectroscopy by enabling a diversity of instrumentation and new measurement capabilities. While a variety of hardware implementations have been realized, considerations in the design of all-IR microscopes have not yet been compiled. Here we describe the evolution of IR microscopes, provide rationales for design choices, and the major considerations for each optical component that together comprise an imaging system. We analyze design choices in illustrative examples that use these components to optimize performance, under their particular constraints. We then summarize a framework to assess the factors that determine an instrument’s performance mathematically. Finally, we summarize the design and analysis approach by enumerating performance figures of merit for spectroscopic imaging data that can be used to evaluate the capabilities of imaging systems or suitability for specific intended applications. Together, the presented concepts and examples should aid in understanding available instrument configurations, while guiding innovations in design of the next generation of IR chemical imaging spectrometers.

Raman Chemical Imaging of Explosive-Contaminated Fingerprints

2009 ◽  
Vol 63 (11) ◽  
pp. 1197-1203 ◽  
Author(s):  
E. D. Emmons ◽  
A. Tripathi ◽  
J. A. Guicheteau ◽  
S. D. Christesen ◽  
A. W. Fountain
Keyword(s):  
Cross Correlation ◽  
Chemical Imaging ◽  
Correlation Technique ◽  
Bright Field ◽  
Characteristic Region ◽  
Biometric Analysis ◽  
Imaging Results ◽  
Raman Chemical Imaging ◽  
Cross Correlation Technique ◽  
Field Imaging

Raman chemical imaging (RCI) has been used to detect and identify explosives in contaminated fingerprints. Bright-field imaging is used to identify regions of interest within a fingerprint, which can then be examined to determine their chemical composition using RCI and fluorescence imaging. Results are presented where explosives in contaminated fingerprints are identified and their spatial distributions are obtained. Identification of explosives is obtained using Pearson's cosine cross-correlation technique using the characteristic region (500–1850 cm−1) of the spectrum. This study shows the ability to identify explosives nondestructively so that the fingerprint remains intact for further biometric analysis. Prospects for forensic examination of contaminated fingerprints are discussed.

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