Multiplex advantages

A more recent, and superior, type of detector, which also benefits from the multiplex advantage, is the charge-coupled device (CCD). The CCD, as used for spectroscopy, has been developed from the CCD detector used in a camcorder. 

In the infrared spectral range in general Fourier transform (FT) interferometers are used. In comparison with dispersive spectrometers FTIR enables higher optical throughput and the multiplex advantage at equivalent high spectral resolution. In... 

The purpose of multiobject spectroscopy (MOS) is to obtain spectra of many objects within a wide field of view. Modem spectrographs have fields of 5-200 arcmin wifhin which several fens to hundreds of objects may be observed simultaneously. With microslit techniques, the multiplex advantage may be increased still further. The main technological options are (Fig. 13) ... 

Multiplex advantage (Fellgett s) all wavelengths are measured simultaneously [86]. 

This multiplex advantage in FT-IR is easiest to understand with respect to the speed of the measurement. For a resolution of 1 cm-1 and frequency range of 400 to 4,000, the FT-IR measurement time is 3,600 times faster than with a dispersive instrument. Consequently, when the time of measurement is limited, the FT-IR has an advantage of two orders of magnitude in speed. For studies of the curing of epoxies this time advantage can be extremely valuable 9). 

The application of FT-IR instrumentation arises from the need for a high signal-to-noise and the multiplex advantage is helpful in this regard. The light output... 

The transform from the interferogram to the spectrum is carried out by the dedicated minicomputer on the instrument. The theory of Fourier-transform infrared spectroscopy has been treated, and is readily available in the literature.21,22,166 Consequently, the advantages of F.t.-i.r. dispersive spectroscopy will only be outlined in a qualitative sense (i) The Fellgett or multiplex advantage arises from the fact that the F.t.-i.r. spectrometer examines the entire spectrum in the same period of time as that required... 

About 10 years ago, the ion-imaging method was developed for the measurement of the velocity of a quantum-state-ionized photoproduct [15,23]. This technique relies on using a position-sensitive ion detector at the end of a TOF mass spectrometer to measure the recoil of photofragments from the centerline of the spectrometer. This technique has a large multiplex advantage over other approaches. 

A measurement with this sequence is equivalent to the frequency domain experiment in Fig. 24, however with the multiplex advantage, i.e. all frequencies are measured simultaneously, not sequentially. The energy left at the intermediate frequencies can simply be discarded. The energies are still finite, since the aimed-at power spectrum can only be approximated during the minimization of E, as in case of the white power spectrum. 

Multiplex Advantage Time advantage gained by obtaining all... 

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