ARL QUANTRIS Top performance CCD based metals analyzer

1
ARL QUANTRISTop performance CCD based metals
analyzer

• ILAP Meeting
• P. Dalager / E. Muller

2
Outline

• Introduction
• Market requirements
• What is the ARL QUANTRIS?
• Instrument description
• Software
• Analytical performance
• Customer benefits
• Conclusions

3
Introduction

• CCD based instruments appeared nearly a decade
  ago
• New technology permitted lower cost, smaller
  bench-top instruments and flexibility
• Potential to analyse all elements without any
  optical compromise
• As long as wavelengths required covered and
  resolution good enough
• Compromises were needed to integrate technology,
  resulted in
• Smaller spectrometers with limited resolution
• Key elements not measurable (N)
• High detection limits, making analysis of minor
  elements not possible at levels required by
  specifications and norms (C, P)
• RSD of minor elements (5-10 ) too limited to
  comply with norms
• RSD of major elements (lt 2 ) too limited to
  optimize usage of alloying elements and save
  production costs
• Stability frequently too limited to provide
  accurate results day by day

4
Introduction

• Thermo (formerly ARL, then Thermo ARL)
• Decades of experience in providing OE
  spectrometers
• Instruments with superior analytical performance,
  stability, reliability and lifetime
• ARL METALS ANALYZER, ARL 3460, ARL 4460
• Thermo has experience with first generation of OE
  solid state detectors based instruments
• ONESPARK (CID)
• ARL EASYTEST and ARL ASSURE (CCD)
• Thermo took challenge to
• break most compromises
• overcome limits experienced
• really achieve performance of traditional PMT
  based instruments

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Market requirements

• Solid state detector based OES with analytical
  figures of merit comparable to PMT instruments
• Analyze CNOPS elements in steel and P in Al
• High reliability, stability and availability
• Flexible instruments with no hardware
  modifications required for calibration extensions
  at customer sites
• Unlimited lines selection for multi-base
  applications
• Black-box operation with easy-to-use instrument
  and software

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What is the ARL QUANTRIS ?

• Second generation OE-CCD spectrometer
• Based on up to three spectrographs and solid
  state detectors
• Utilizes high end linear CCDs
• Utilizes high end CCS source
• First CCD based instrument
• with analytical performance equivalent to
  traditional PMT based instruments
• able to analyse elements C, N, P, S accurately
  even at lowest concentrations

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Outline

• Introduction
• Market requirements
• What is the ARL QUANTRIS?
• Instrument description
• Choice of technical solutions
• Spectrometer optics
• Solid state imagers
• Excitation source
• Instrument stability
• Hardware description
• Analytical development
• Software
• Analytical performance
• Customer benefits
• Conclusions

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Choice of technical solutionSpectrometer optics

• Three alternatives investigated
• Paschen-Runge with chained linear solid state
  detectors along Rowland circle
• Echelle with 2D solid-state detectors
• Flat-field with linear solid-state detectors

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Instrument descriptionOptics Flat field
Primary slit
Grating
Detector
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Instrument descriptionOptics Flat field

• Advantages
• Simple configuration
• Simple detection system
• Simple mapping procedure (calibration, drift
  correction)
• ? Simplicity of configuration facilitates
  manufacturing of stable and reliable instruments
• Numerous manufacturers of linear detectors

• Difficulties
• Fields not flat over long distances
• Linear CCDs not arbitrary long
• ? Compromise spectral range/ resolution
• ? Narrow slits for good resolution
• ? Reduced light flux
• ? Limited dynamic range
• High light flux for good dynamic range
• ? Broader slits needed
• ? Lower resolution
• Works only in 1. order of diffraction
• ? Resolution limited for some critical wavelengths

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Choice of technical solutionOptics ARL QUANTRIS

• Up to three flat field spectrographs
• Separation of spectral range to be analyzed
  within 3 modules
• 129-200 nm (N, C, P, S)
• 200-410 nm
• 410-780 nm (Na, Li, K )
• Optimized light collection in each module through
  specific lenses and gratings
• Direct reading for all 3 modules to avoid fibre
  optics
• No aging of fibres and no replacement necessary

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Choice of technical solutionSolid state imagers

• Multi-parameter evaluation of CMOS and CCD
  techniques

• CMOS
• Technology of choice for high-volume,
  space-constrained applications where image
  quality requirements low
• Security cameras
• PC videoconferencing
• Automotive in-vehicle uses ...
• CCD
• Most suitable technology for high-end imaging
  applications
• Digital photography
• High-performance industrial imaging
• Most scientific and medical applications

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Choice of technical solution Detector ARL
QUANTRIS

• CCD
• Specifically designed for high end industrial,
  scientific or military applications
• Color RGB CCDs used in monochromatic mode
• Increases signal/noise ratio
• Open new possibilities for increased dynamic
  range
• Lumogen coating for CCDs used in VUV
  spectrograph to improve quantum efficiency
• Reduced quantum efficiency at lower wavelengths
• Coatings mandatory to increase quantum efficiency
  below 200 nm

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Choice of technical solution Source ARL QUANTRIS

• Two types of sources utilized on PMT instruments
• HIREP on ARL METALS ANALYZER and ARL 3460
• Current follows natural decay imposed by RLC
  circuit
• 8 different excitation conditions available
• Patented Current Controlled Source (CCS) on ARL
  4460
• The only servo-controlled digital source on
  market
• Solid state electronics
• High degree of flexibility in selection of peak
  current, frequency and current waveforms
• Enables optimization of all figures of merit for
  each metal
• Achieves best accuracy, sensitivity and
  reproducibility
• Compact design close to spark stand in a Faraday
  cage
• Suppresses RF leakage and improves general
  stability

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Choice of technical solution Source Our solution

• ARL QUANTRIS optics with limited resolution in
  comparison to Paschen-Runge optics with 1 m focal
  length
• CCS source best tool to compensate limitations
  and achieve best results
• ? CCS source selected

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Choice of technical solution Stability

• Long-term stability of utmost importance in harsh
  environments to ensure quality analytical data
• Key influence on precision, accuracy and speed of
  analysis
• Time spent in drift correction is time lost
• Drift corrections are expensive
• Frequent drift correction can contribute to
  errors
• Metals production depends on stable analytical
  instruments to ensure the process is under
  control
• First generation of CCD based instruments dont
  have best stability reputation
• Exception being ARL ASSURE thanks to flat field
  architecture
• Thermo established reputation with stable
  instruments
• Company knowledge exploited to provide stable
  instruments

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Choice of technical solution Stability

• Easier to achieve stability with simple flat
  field architecture
• Well proven cast iron spectrometer
• Provides unrivaled stability both on short and
  long term
• Spectrometer running under vacuum
• Provides rigidity
• Independant from atmospheric pressure variations
• Thermo-controlled CCDs to 0.5C at 0.5-2C
• Achieves low noise in addition to stability
• Water-cooled stand
• Automatic optical alignment and spectrum
  profiling on each CCD

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Hardware descriptionStand

• Stand main features
• With 3 optical channels
• Argon flow optimized by computer simulation
• Casted analysis table for light passes, argon
  admission and exhaust optimization
• Quick analysis table exchange
• Indirect water cooling table
• Very low stand-by flow
• Fast flush and dust blow out system
• Use of short pulsed argon jets
• Allow to reduce argon flush time even with
  Nitrogen analysis
• Keep the spark chamber free of extra dust over
  extended time
• Consequently reduces maintenance frequency and
  down time

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Hardware descriptionOptical system main features

• Spectrometer in cast iron, under dry vacuum
• 3 spectrographs with flat field diffraction
  system
• Focal length 200 mm
• Primary slit width 15 µm
• Holographic aberration corrected concave gratings
• VUV spectrograph 3240 gr/mm (at grating center)
• Basic spectrograph 1105 gr/mm (at grating
  center)
• Optional alkaline spectrograph 590 gr/mm (at
  grating center)
• Average dispersion
• VUV spectrograph 1.2 nm/mm
• Basic spectrograph 3.5 nm/mm
• Optional alkaline spectrograph 6.7 nm/mm
• Average bandpass per pixel
• VUV spectrograph 8 pm/pixel
• Basic spectrograph 24 pm/pixel
• Optional alkaline spectrograph 43 pm/pixel

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Hardware descriptionOptical system

• Spectrometer views

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Analytical developmentAnalytical conditions (2)

• Fe base
• Standard timings and source parameters
• CCD and acquisition parameters

• Adjusted to obtain max. intensity on IS lines
  (needs number of integrations to be adapted)
• Analysis time
• Fe base 31s (computation time added)
• Al base 29 s (computation time added)

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Analytical developmentPreliminary Manipulation
of Spectral Data

• After summation of intensities of elementary
  integration times
• 3 spectra obtained for each CCD line (RGB)
• Added to obtain 1 spectrum for each CCD with up
  to ? 3 x better S/N
• Pixel intensities of all CCDs used for
  computations (next slides)
• Pixel intensities of all CCDs also stored in a
  file allowing graphical display of the spectra
• With header with various information
• With polynomial coefficients and pixel
  intensities for each CCD
• Coefficients make spectra in nm from different
  instruments comparable

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Analytical developmentNumerical Processing -
Generalities

• Weaker performance of CCDs vs. PMTs
• Sensitivity typically 2-3 orders of magnitude
  lower
• Lower precision
• Numerical processing offers unique
  differentiators to the ARL QUANTRIS
• Because spectrum available and almost no
  limitation on line selection
• Drawbacks partly compensated by "massaging"
  spectra with
• Drift correction at each acquisition
• Processing windows with full flexibility
• Various filtering modes
• Various  intensity modes 
• Various background subtraction modes
• Use of best internal standard for each analyte
  line
• Deconvolution
• Enormous potential, at every level !

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Analytical developmentNumerical Processing For
drift correction

• Drift correction
• Drifts unavoidable !
• For each CCD, at each acquisition
• Well defined and resolved lines compared to a
  "mask"
• Set of reference lines
• Drift correction algorithm "moves and deforms"
  spectrum in order to find the smallest difference
  with reference lines
• Special algorithms to find accurate maxima
  positions of measured lines
• Parameters similar to a and b for
  restandardization

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Analytical developmentNumerical Processing
Processing window

• Chosen to eliminate interferences as much as
  possible
• Chosen to solve desperate situations
• Can be shrunk to a line ? amplitude measurement

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Analytical developmentNumerical Processing
Filtering

• Smoothing filters matched to line characteristics
• Improve pixel reproducibility
• Reduce noise
• Improve reproducibility of integration

Raw run 1
Low-pass Filter
Raw run 2
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Analytical developmentNumerical Processing
Filtering

• Typical improvements due to smoothing filters
• SD calculated on 10 runs performed on SUS RE12

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Analytical developmentNumerical Processing
Background Subtraction

• Various modes
• Off-Peak ( Bg )
• On-peak
• If off-line background signal
  not available
• Rectangular or trapezoidal
• None
• Quality of background on- peak not always
  sufficient
• If good background improves sensitivity, bad
  background can degrade reproducibility

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Outline

• Introduction
• Market requirements
• What is the ARL QUANTRIS?
• Instrument description
• Software
• Analytical performance
• Customer benefits
• Conclusions

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SoftwareWinOE the powerful assistant

• First Windows based version launched 1991
• Regular releases (13) to add functions, improve
  ease-of-use, support new OS
• Current version 3.1
• Runs on all Thermos PMT based instruments
• Runs on Windows 2000
• Most powerful package on market
• Most robust package on market
• Simplest to use package on market

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SoftwareNew WinOE 3.2

• Main novelty supports ARL QUANTRIS now!
• Line library manager
• Libraries managed per matrix
• Graphical tool to display the spectra acquired
  from the 3 CCD's and identity unknown peaks

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SoftwareNew WinOE 3.2 Lines library manager

• Lines libraries organized per base Fe, Al, Cu
• A base lines library includes selected spectral
  lines, spectrum processing algorithms and
  information
• Lines libraries available separately
• Multi-base capability
• New elements added without hardware change
• Easy addition in analytical programs of any line
  included within the installed lines libraries
• Lines of other bases need corresponding library

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SoftwareNew WinOE 3.2 Qualitative analysis

• Spectra display function, dedicated to the
  display of analysis spectra
• On-line and off-line view
• Spectra manipulation tools
• Peak search function
• Also called finger print mode
• Permits qualitative analysis of any element in
  wavelength library gt 146000 lines
• Perfect tool for metallurgical research
• User friendly thanks to a modern look 'n feel
• Evolving functionality
• Nice tool for metallurgical research

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Outline

• Introduction
• Market requirements
• What is the ARL QUANTRIS?
• Instrument description
• Software
• Analytical performance
• Customer benefits
• Conclusions

35
Analytical PerformanceNew detection limit
definition

• Traditional DL calculation method
• DL 3 s relative BEC
• s relative relative standard deviation stored for
  the pure matrix sample with 10 runs
• With background subtraction, too easy to
  artificially show very low DLs
• Alternative method had to be defined
• DL tsSensitivity
• t Extracted from Student table for p 99.5 (3
  s) and df9? t 3.2498
• s standard deviation in intensity measured on
  pure sample
• Sensitivity slope of calibration curve at zero
  concentration
• (C1- Co/(I1-Io)
• Definition already used by some customers
• Most accurate method
• Gives very similar results on PMT based
  instruments with definition above

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Analytical Performance Fe base detection limits
(3 s)

• Key elements
• Steel C, N, P, S, Pb, Si, Mn
• Cast iron Pb, Mg, La, CeN
• Garanteed values at Thermo
• Calculation according to norms
• Not every competitor calculated according to
  norms
• ARL QUANTRIS in steel
• 4 x inferior to ARL 3460
• C better
• 5 x better than ARL ASSURE
• ARL QUANTRIS in cast iron
• Equivalent to 3460

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Analytical Performance Fe base reproducibility
example (1 s)

• Low alloy steel
• 10 runs per sample
• Key elements
• Minor C, N, P, S, Pb, Si, Mn
• Major Co, Cr, Ni, Mn, Mo, W
• ARL QUANTRIS
• 15 lt ARL 3460
• 4 x better than ARL ASSURE

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Analytical Performance Fe base reproducibility
example (1 s)

• Cast iron
• Sample CKD 248
• 10 runs per sample
• Key elements
• Minor Pb, Mg, La, Ce
• Major C, Cr, Ni, Mo
• ARL QUANTRIS
• 50 better than ARL 3460
• 7 x better than ARL ASSURE
• RSD major elements
• C, Ni gt ARL 3460
• Cr, Mo lt ARL 3460
• RSD trace elements
• Pb ARL 3460

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Analytical Performance Fe base reproducibility

• Excellent element

• More limited element

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Analytical Performance Fe base accuracy

• Calibration curves examples
• Excellent linearity
• Reduced absorption effects
• Excellent Standard Errors of Estimate (SEE)

C in cast iron
Cr in cast iron
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Analytical Performance Fe base accuracy (SEE)

• Cr-Ni calibration
• Same ranges and samples on both instruments
• Key elements
• Minor C, N, P, Pb, S
• Major Co, Cr, Ni, Mn, Mo, W
• Residual errors, QUANTRIS
• Better on key elements
• Cr, Mn

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Analytical Performance Fe base stability

• Stability of utmost importance when performing
  routine analyses
• With vacuum spectrometer, automatic optical
  alignment and spectrum profiling, demonstrates
  exceptional stability
• Reduces need for drift correction and allows more
  time for production sample analyses
• Examples show long-term stability of elements N
  in a low alloy steel and Mg in a cast iron over 7
  days without any intermediate drift correction
• Standard deviation achieved remains in range of
  2x precision

43
Analytical Performance Al base detection limits
(3 s)

• Typical values yet
• Application still in development
• Guaranteed values to be slightly higher
• Key elements
• As, Ca, Cd, Li, Na, P, Pb, Sb, Sn
• ARL QUANTRIS in Al
• 10 x inferior to ARL 3460

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Analytical Performance Al base reproducibility
example (1 s)

• Al-Si-Cu sample
• 10 runs per sample
• ARL QUANTRIS
• Clearly better on major elements
• Sometimes inferior on minor elements

45
Analytical Performance Al base reproducibility
example (1 s)

• Majors (gt 500 ppm) in SUS vs. datasheet ARL 3460

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Outline

• Introduction
• Market requirements
• What is the ARL QUANTRIS?
• Instrument description
• Software
• Analytical performance
• Customer benefits
• Conclusions

47
Customer benefitsStability

• Feature
• Instrument virtually drift free
• Simple flat field architecture
• Well proven cast iron spectrometer running under
  vacuum
• Thermo-controlled CCDs to 0.5 C at 5C
• Water-cooled stand
• Automatic optical alignment and spectrum
  profiling on each spectrograph
• Benefit
• Instrument delivers dependable performance 24 x 7
  x 365
• Minimizes drift correction procedures and keeps
  instrument available for its primary task
• Analysis of unknown samples
• Minimizes consumption of expensive drift
  correction samples

48
Features and benefitsReproducibility

• Feature
• Instrument divided in 3 spectrographs
• Thermally controlled CCDs for low noise
• Optimal analytical line for each matrix and even
  each quality
• Optimal Internal Standard, optimized for each
  analytical line
• Optimal data treatment for each line (smoothing,
  filtering, background substraction)
• Digital source with optimum waveform for each
  matrix
• Benefit
• Confidence in reproducibility of results
  delivered
• Precision of minor elements (RSD 1-5 ) enough to
  comply with specifications and norms
• Precision of major elements (RSD 0.2-1 ) permits
  minimal usage of alloying elements and save
  production costs

49
Features and benefits Flexibility

• Feature
• Full spectrum available with no spectral line
  compromize
• Wavelength coverage from 129 nm to 780 nm
• Extension of analytical needs with no hardware
  modifications
• In some cases spectrograph 410-780 nm could be
  requested
• Fast change tables and electrodes for
  multi-matrix applications
• Benefit
• All elements requested by the metals industry can
  be analyzed
• Easy identification of unknown elements
• Low investment costs
• Up-grades performed with minimal downtime
• Easier operation in multi-matrix applications
• Lowest operating costs

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Outline

• Introduction
• Market requirements
• What is the ARL QUANTRIS?
• Instrument description
• Software
• Analytical performance
• Customer benefits
• Conclusions

51
Conclusions

• Thermo not first with CCD-based OE spectrometers
• But when we do it, we do it right !!
• For first time CCD based spectrometer with true
  performance of PMT based instruments
• All spectral lines for all metals types
• Full and continuous wavelength coverage from
  129-870 nm
• For the first time low C, N analysable with
  CCD-based instrument
• Detection limits, reproducibility, accuracy,
  stability, reliability
• Rugged construction to be used in hostile
  environments
• Stability to minimize drift corrections
• Automatic optical alignment and spectrum
  profiling

52
Conclusions

• Perfect instrument for metals producers and
  transformers
• Lower operating costs, flexibility for
  identification of unknown elements
• Perfect instrument for industrial central
  laboratories, analytical services contract
  laboratories
• Multi-matrix applications without any compromizes
• Permits also lowest costs of ownership
• Price difference rapidly offset by savings on
  costs of ownership
• Easily up-gradable at lower costs