PPT Slide
- Secondly, in systems that are source noise-limited, the Fellgett disadvantage applies.
- This arises because all regions of the spectrum are observed simultaneously. Therefore, if noise occurs in one part of the radiation from the infrared source, it will be spread throughout the spectrum in an FTIR system.
- In a dispersive system, the noise would be seen only in the region of the spectrum in which it arose.
- Fortunately, in mid-infrared systems, as most commnly used, the system is detector noise-limited, therefore the Fellgett advantage applies, but not the Fellgett disadvantage.