Single-Shot Multiwavelength Imaging of Laser Plumes

1998 ◽  
Vol 52 (2) ◽  
pp. 179-186 ◽  
Author(s):  
Matthew P. Nelson ◽  
Wendy C. Bell ◽  
Michael L. McLester ◽  
M. L. Myrick
Keyword(s):  
Fiber Optics ◽  
Optical Fibers ◽  
Ccd Camera ◽  
Chemical Imaging ◽  
Single Shot ◽  
Charge Coupled Device ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown ◽  
Optic Array ◽  
A Charge

A novel optical approach to single-shot chemical imaging with high spectroscopic resolution is described with the use of a prototype dimension-reduction fiber-optic array. Images are focused onto a 30 × 20 array of hexagonally packed 250 μm o.d. f/2 optical fibers that are drawn into a 600 × 1 distal array with specific ordering. The 600 × 1 side of the array is imaged with an f/2 spectrograph equipped with a holographic grating and a charge-coupled device (CCD) camera for spectral analysis. Software is used to extract the spatial/spectral information contained in the CCD images and de-convolute them into wavelength-specific reconstructed images or position-specific spectra that span a 190 nm wavelength space. “White light” zero-order images and first-order spectroscopic images of laser plumes have been reconstructed to illustrate proof-of-principle. Index Headings: Fiber optics; Chemical imaging; Spectroscopic imaging; Charged-coupled device (CCD); Laser-induced breakdown spectroscopy (LIBS).

Man-Portable Laser-Induced Breakdown Spectroscopy System for in Situ Characterization of Karstic Formations

2008 ◽  
Vol 62 (11) ◽  
pp. 1250-1255 ◽  
Author(s):  
J. Cuñat ◽  
F. J. Fortes ◽  
L. M. Cabalín ◽  
F. Carrasco ◽  
M. D. Simón ◽  
...  
Keyword(s):  
Field Testing ◽  
Array Detector ◽  
Depth Information ◽  
Charge Coupled Device ◽  
Breakdown Spectroscopy ◽  
Ccd Array ◽  
Laser Induced Breakdown ◽  
Environment Identification ◽  
A Charge ◽  
Identification Analysis

This paper reports the development and field testing of a man-portable instrument based on laser-induced breakdown spectrometry (LIBS) for inspection and analysis of speleothems. The 50 mJ of a Q-switched Nd:YAG laser operating at 1064 nm was used to generate a plasma on the sample. Plasma emission was then guided using a fiber-optic cable to a 1/10 m spectrometer equipped with a charge-coupled device (CCD) array detector. Plasma light was automatically processed in order to obtain surface and in-depth information from the speleothems. A field campaign in the interior of Nerja Cave (a large karstic formation in the South of Spain) has been carried out, aimed at evaluating the analytical performance of the instrument when operating in an unfriendly environment. Identification analysis of the speleothems' alteration layers and depth profiles of Sr and Ca is carried out and reported.

scholarly journals Spectroscopic flat-fields can be used for precision CCD gain and noise tests

2021 ◽  
Vol 38 ◽  
Author(s):  
J. Gordon Robertson
Keyword(s):  
Ccd Camera ◽  
Matched Pair ◽  
Optical Fibres ◽  
Charge Coupled Device ◽  
Small Areas ◽  
Flat Field ◽  
Basic Parameters ◽  
The Mean ◽  
A Charge ◽  
Analogue To Digital

Abstract One of the basic parameters of a charge coupled device (CCD) camera is its gain, that is, the number of detected electrons per output Analogue to Digital Unit (ADU). This is normally determined by finding the statistical variances from a series of flat-field exposures with nearly constant levels over substantial areas, and making use of the fact that photon (Poisson) noise has variance equal to the mean. However, when a CCD has been installed in a spectroscopic instrument fed by numerous optical fibres, or with an echelle format, it is no longer possible to obtain illumination that is constant over large areas. Instead of making do with selected small areas, it is shown here that the wide variation of signal level in a spectroscopic ‘flat-field’ can be used to obtain accurate values of the CCD gain, needing only a matched pair of exposures (that differ in their realisation of the noise). Once the gain is known, the CCD readout noise (in electrons) is easily found from a pair of bias frames. Spatial stability of the image in the two flat-fields is important, although correction of minor shifts is shown to be possible, at the expense of further analysis.

Development and Commercial Evaluation of Laser-Induced Breakdown Spectroscopy Chemical Analysis Technology in the Coal Power Generation Industry

2002 ◽  
Vol 56 (1) ◽  
pp. 70-74 ◽  
Author(s):  
Bruce L. Chadwick ◽  
Doug Body
Keyword(s):  
Heterogeneous Materials ◽  
Laser Induced Breakdown Spectroscopy ◽  
Acid Extraction ◽  
Charge Coupled Device ◽  
Breakdown Spectroscopy ◽  
Power Stations ◽  
Laser Induced Breakdown ◽  
Fuel Source ◽  
Multiple Charge

An instrumentation variation on laser-induced breakdown spectroscopy (LIBS) has been developed and applied in the operations of power generating companies utilizing low-ash lignite as the fuel source. The instrument design allows simultaneous determination of all detectable elements using a multiple spectrograph and a synchronized, multiple charge-coupled device (CCD) spectral acquisition system. The application of internal ratio analysis has enabled the development of a stable system that can be operated routinely for over a month without recalibration. Detection limits vary depending on the element but are typically on the order of 0.01% by weight for heterogeneous materials such as the moist lignite used in these power stations. Independent testing of the instrument has shown good correlation between the routine LIBS analysis and the analysis of the coal via acid extraction techniques for key ash-forming elements. Testing over a one month period shows excellent correlation between the two methods for elements such as Al ( R = 0.96) and Na ( R = 0.92). The principle limitation is not the accuracy of the LIBS method but rather the inherent errors in sampling heterogeneous materials such as lignite. Because the LIBS analysis takes less than 30 seconds it has clear advantages over traditional methods used in elemental analysis for these materials.

scholarly journals Laser-Induced Breakdown Spectroscopy and Principal Component Analysis for the Classification of Spectra from Gold-Bearing Ores

2019 ◽  
Vol 74 (1) ◽  
pp. 42-54 ◽  
Author(s):  
Daniel Diaz ◽  
Alejandro Molina ◽  
David W. Hahn
Keyword(s):  
Principal Component Analysis ◽  
Limit Of Detection ◽  
Principal Component ◽  
Component Analysis ◽  
Emission Lines ◽  
Laser Induced Breakdown Spectroscopy ◽  
Single Shot ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown

Laser-induced breakdown spectroscopy (LIBS) and principal component analysis (PCA) were applied to the classification of LIBS spectra from gold ores prepared as pressed pellets from pulverized bulk samples. For each sample, 5000 single-shot LIBS spectra were obtained. Although the gold concentrations in the samples were as high as 7.7 µg/g, Au emission lines were not observed in most single-shot LIBS spectra, rendering the application of the usual ensemble-averaging approach for spectral processing to be infeasible. Instead, a PCA approach was utilized to analyze the collection of single-shot LIBS spectra. Two spectral ranges of 21 nm and 0.15 nm wide were considered, and LIBS variables (i.e., wavelengths) reduced to no more than three principal components. Single-shot spectra containing Au emission lines (positive spectra) were discriminated by PCA from those without the spectral feature (negative spectra) in a spectral range of less than 1 nm wide around the Au(I) 267.59 nm emission line. Assuming a discrete gold distribution at very low concentration, LIBS sampling of gold particles seemed unlikely; therefore, positive spectra were considered as data outliers. Detection of data outliers was possible using two PCA statistical parameters, i.e., sample residual and Mahalanobis distance. Results from such a classification were compared with a standard database created with positive spectra identified with a filtering algorithm that rejected spectra with an Au intensity below the smallest detectable analytical LIBS signal (i.e., below the LIBS limit of detection). The PCA approach successfully identified 100% of the data outliers when compared with the standard database. False identifications in the multivariate approach were attributed to variations in shot-to-shot intensity and the presence of interfering emission lines.

Determination of Copper in A533b Steel for the Assessment of Radiation Embrittlement Using Laser-Induced Breakdown Spectroscopy

1996 ◽  
Vol 50 (3) ◽  
pp. 306-309 ◽  
Author(s):  
Wolfgang E. Ernst ◽  
Dave F. Farson ◽  
D. Jason Sames
Keyword(s):  
Laser Beam ◽  
Fiber Optics ◽  
Nuclear Power ◽  
Power Plants ◽  
Pressure Vessels ◽  
Laser Induced Breakdown Spectroscopy ◽  
Radiation Embrittlement ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown

Determination of radiation embrittlement in nuclear reactor pressure vessels is crucial to assessing safe operative lifetimes for many aging nuclear power plants. Conservative nuclear fluence estimates and trace impurity diagnosis of the weldment material are the basis of radiation embrittlement analysis. Copper is thought to be a key impurity contributing to radiation embrittlement. In this paper, the application of laser-induced breakdown spectroscopy (LIBS) as a means to assess radiation embrittlement by the detection and quantification of copper in A553b steel was investigated. A LIBS configuration completely coupled by fiber optics was attempted, but because of low laser power and fiber losses, fiber-optic delivery of the laser beam was unsuccessful. Consequently, hard optics (lenses and mirrors) were employed for laser beam delivery. The plasma emission was delivered successfully via fiber optics to the detection apparatus. Copper measurements were made from custom-fabricated steel samples. Comparison of the LIBS results to an independent atomic absorption spectrophotometry (AAS) analysis showed LIBS to be of comparable accuracy, especially in low-level copper samples.

Description And Preliminary Performance Of A Charge-Coupled Device (CCD) Camera

1981 ◽  
Author(s):  
A. Bouere ◽  
J. Cretolle ◽  
B. Fort ◽  
R. Jouan ◽  
M. Gorisse ◽  
...  
Keyword(s):  
Ccd Camera ◽  
Charge Coupled Device ◽  
A Charge

In situ chemical imaging of lithiated tungsten using laser-induced breakdown spectroscopy

2014 ◽  
Vol 452 (1-3) ◽  
pp. 10-15 ◽  
Author(s):  
Cong Li ◽  
Xingwei Wu ◽  
Chenfei Zhang ◽  
Hongbin Ding ◽  
Jiansheng Hu ◽  
...  
Keyword(s):  
Chemical Imaging ◽  
Laser Induced Breakdown Spectroscopy ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown
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