Echelle system

To avoid the limited wavelength coverage associated with one-dimensional systems, several groups have assembled and demonstrated the feasibility of echelle systems employing either a vidicon (99) or an SEC tube (95). To overcome the somewhat limited linear dynamic range characteristics of vidicons, these systems employ random accessing. 

Switch-Board Optics. The preceding discussion has summarized the various approaches which have been taken to achieve a practical spectrometer for SMA. The direct reader, the vidicon detector, and the development of image device/echelle systems... 

Echelle spectrometers can also be made small, when only part of the spectrum is to be used, while still having a considerably high spectral resolution. In Echelle systems, dedicated parts of the spectrum are often measured with a separate built-in spectrometer. This is e.g. the case in ICP-OES for the spectral range where the most sensitive alkali lines are found [345],... 

Handbook of Spectral Line Characteristics for the DC Plasma/Echelle Systems, Spectrametrlcs Inc. 1982. 

Sequential and simultaneous ICP systems of many types are available from numerous instrument manufacturers. Most are available in radial or axial view, or both. Most spectrometers can be purged to reach 160 nm. Examples of some of the companies who make ICPs and DCPs are given. Jobin Yvon, Inc. makes a line of PMT-based high-resolution sequential systems, simultaneous systems, and combination sequential-simultaneous systems. PerkinElmer Inc. makes a scanning ICP with CCD detection, and a line of simultaneous CCD-based Echelle systems. Leeman Laboratories, Inc. makes an Echelle ICP spectrometer with an aperture grid available as a sequential system with rapid scanning PMT detection, a simultaneous system with a PMT array, and a combination system. Varian, Inc. makes a sequential ICP with PMT detection and a simultaneous system with CCD detection. ThermoElemental offers ICP Echelle spectrometers with CID detection and a sequential diffraction grating instmment with PMT detection. 

As CCD arrays have a two-dimensional arrangement of the pixels, their use in the case of miniaturized echelle spectrometers allows larger parts of the atomic emission spectrum to be recorded with higher resolution. The trends towards this development are exemplified by the construction of dedicated echelle systems for specific parts of the optical spectrum. 

Detection limits achieved for a number of elements are compared with those from the ARL Beckman DC plasma echelle system in Table 4.2 [50]. Clearly, the detection limits are very comparable. The detection... 

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