What if more than 4 channels or wavelengths need to be monitored. Is a second detector necessary?
Normally 3 gas channels and a reference are monitored with a 4 channel detector. If you need to monitor more than 4 channels you have different options. Often two different 4 channel detectors are used in parallel using an external uncoated Si beamsplitter in front of them. Alternatively, a single channel detector with a filter wheel having the number of needed NBP filters for each spectral channel (up to 8 channels are common) can be applied. A more sophisticated possibility is to use InfraTec’s Fabry-Perot detector LFP where a continuous spectrum can be scanned.
