Double monochromator instrument diagram

Figure 3.1 Schematic diagram of an AAS spectrometer. A is the light source (hollow cathode lamp), B is the beam chopper (see Fig. 3.2), C is the burner, D the monochromator, E the photomultiplier detector, and F the computer for data analysis. In the single beam instrument, the beam from the lamp is modulated by the beam chopper (to reduce noise) and passes directly through the flame (solid light path). In a double beam instrument the beam chopper is angled and the rear surface reflective, so that part of the beam is passed along the reference beam path (dashed line), and is then recombined with the sample beam by a half-silvered mirror.

FIGURE 13-23 Optical diagram of the Varian Cary 300 double-dispersing spectrophotometer. The instrument is essenti ly identical to that shown in Figure 13-22, except that a second monochromator is added immediately after the source. (Varian Inc.. Palo Alto, CA.)... 

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