Spettrometri CCD

Spettrometro CCD Spettrometro PMT Fluorescenza XRF Diffrazione XRD Spettrometro EDS Strumenti Usati Accessori Testing Machines

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Spettrometri CCD:
Spettrometri ad Emissione Ottica - Tecnologia CCD Breakthrough in CCD Based OES-Spark Spectrometers While requiring simple preparation, low cost of ownership, Optical Emission Spectroscopy (OES) offers a high level of performance at extremely high speed for elemental analysis in metals. It has therefore been the method of choice for the analysis in the metals industries for many years. For about a decade, solid state detector technology has been used in some spectrometers in place of photo-multiplier tubes (PMT’s), because it allowed the design of optics with reduced dimensions, and increased flexibility regarding analytical lines selection, multi-matrix applications and up-grades. The most adopted solid-state detectors are the CCDs (Charge Coupled Devices). This kind of detector has the advantage that all the lines from the monitored spectral range are available for analytical purpose, provided that they are sufficiently resolved. Until recently, it was thought that spectrometers based on CCDs have lower performance, in particular higher detection limits and lower precision in comparison with, now classical, PMT instruments. We show in this article that a new generation of instruments, that combine the advantages of some of the most recent technologies used in high-end OES instruments with those of CCD detectors, for instance the flexibility on analytical lines and signal processing possibilities, partly overcomes the drawbacks of these detectors, namely their lower sensitivity and limited resolution. Innovative Architecture, Innovative Mathematical Treatment of the Signal A flat-field configuration was chosen for the optics of the ARL CCD Spectrometer, because this configuration is the simplest for ensuring stability and reliability and because flat-field gratings are designed to focus the light onto a plane surface, which makes them perfectly suited to take maximum benefit from solid-state detectors. The spectrometer body, made of cast iron, operates under vacuum. This ensures excellent short- and long-term stability. This is only possible if the characteristics of the spectrometer are reproducible and if the stability is excellent. The design of the ARL CCD Spectrometer clearly provides this. Typically, the sensitivity of a CCD detector is two to three orders of magnitude lower than the sensitivity of a PMT. An obvious way to compensate for lower sensitivity of the CCD detectors is to reduce the spectral noise. The CCD detector and the readout electronics are subject to different types of noises that can be referred to as thermal noise, shot noise and noise related to the amplifier and signal processor. A fraction of the thermal noise can be suppressed by cooling the CCDs (close to 0 C in the case of the ARL Spectrometer). In order to reduce the remaining noise, various numerical filters can be applied to the spectrum. Filters matching the characteristics of the spectral region of interest (resolution, integration wavelength window) allow optimal smoothing of the noisy intensities. Numerical filtering induces a small broadening of the peak and a reduction in the signal to background ratio. (pure sample) are diminished, which improves the reproducibility. Conclusions We have shown that a new generation of CCD instruments provides improved performances partly bridging the gap that existed until today between CCD and PMT spectrometers. Based on proven and innovative technologies, the ARL CCD Spectrometer benefits from the advantages of full complex mathematical processing made possible by the well-adapted hardware. In some respects, the new CCD instrument provides better performance than traditional instruments. Some other important aspects couldn’t be addressed in the limited frame of this article. The described construction and numerical methods, as well as other innovations also ensure excellent accuracy and stability figures. Finally the instrument is perfectly suited for multi-matrix analyses, since all the improvements apply to the other metallic bases.

Spettrometri CCD:

Spettrometri ad Emissione Ottica - Tecnologia CCD

Breakthrough in CCD Based OES-Spark Spectrometers
While requiring simple preparation, low cost of ownership, Optical Emission Spectroscopy (OES) offers a high level of performance at extremely high speed for elemental analysis in metals. It has therefore been the method of choice for the analysis in the metals industries for many years. For about a decade, solid state detector technology has been used in some spectrometers in place of photo-multiplier tubes (PMT’s), because it allowed the design of optics with reduced dimensions, and increased flexibility regarding analytical lines selection, multi-matrix applications and up-grades. The most adopted solid-state detectors are the CCDs (Charge Coupled Devices).
This kind of detector has the advantage that all the lines from the monitored spectral range are available for analytical purpose, provided that they are sufficiently resolved. Until recently, it was thought that spectrometers based on CCDs have lower performance, in particular higher detection limits and lower precision in comparison with, now classical, PMT instruments. We show in this article that a new generation of instruments, that combine the advantages of some of the most recent technologies used in high-end OES instruments with those of CCD detectors, for instance the flexibility on analytical lines and signal processing possibilities, partly overcomes the drawbacks of these detectors, namely their lower sensitivity and limited resolution.

Innovative Architecture, Innovative Mathematical Treatment of the Signal
A flat-field configuration was chosen for the optics of the ARL CCD Spectrometer, because this configuration is the simplest for ensuring stability and reliability and because flat-field gratings are designed to focus the light onto a plane surface, which makes them perfectly suited to take maximum benefit from solid-state detectors. The spectrometer body, made of cast iron, operates under vacuum. This ensures excellent short- and long-term stability. This is only possible if the characteristics of the spectrometer are reproducible and if the stability is excellent. The design of the ARL CCD Spectrometer clearly provides this.
Typically, the sensitivity of a CCD detector is two to three orders of magnitude lower than the sensitivity of a PMT. An obvious way to compensate for lower sensitivity of the CCD detectors is to reduce the spectral noise. The CCD detector and the readout electronics are subject to different types of noises that can be referred to as thermal noise, shot noise and noise related to the amplifier and signal processor. A fraction of the thermal noise can be suppressed by cooling the CCDs (close to 0 C in the case of the ARL Spectrometer). In order to reduce the remaining noise, various numerical filters can be applied to the spectrum. Filters matching the characteristics of the spectral region of interest (resolution, integration wavelength window) allow optimal smoothing of the noisy intensities. Numerical filtering induces a small broadening of the peak and a reduction in the signal to background ratio. (pure sample) are diminished, which improves the reproducibility.

Conclusions
We have shown that a new generation of CCD instruments provides improved performances partly bridging the gap that existed until today between CCD and PMT spectrometers. Based on proven and innovative technologies, the ARL CCD Spectrometer benefits from the advantages of full complex mathematical processing made possible by the well-adapted hardware. In some respects, the new CCD instrument provides better performance than traditional instruments. Some other important aspects couldn’t be addressed in the limited frame of this article. The described construction and numerical methods, as well as other innovations also ensure excellent accuracy and stability figures. Finally the instrument is perfectly suited for multi-matrix analyses, since all the improvements apply to the other metallic bases.