Detection systems, grating-based

Grating-Based Label-Free Detection Systems... 

These are also known as multi-channel spectroscopic methods and are based on a peculiar multiplexing mode denominated optical multiplexing or wave-length-division multiplexing . The detection system commonly used involves several Independent detectors strategically located so that the dispersed radiation strikes each of them discriminately. The optical dispersion can be accomplished with the aid of a diffraction grating or prism, or both (6chelle dispersion ). 

The efficiency is further reduced by the efficiency of the grating of the monochromator itself, which is 60 % to 80 % at best. Moreover, the detection bandwidth is usually much smaller than the width of the fluorescence band of the fluorophore. Therefore, the efficiency of a monochromator-based system can be orders of magnitude smaller than that of a filter-based system (see below). 

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. 

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