Patent ID: 7630835

Claim:
A process to calculate a relative humidity, an absolute humidity, or a water vapor concentration, the process comprising: receiving at a detector a first frequency of electromagnetic radiation, the first frequency of electromagnetic radiation transmitted through a medium within a frequency range of approximately 0.1 TeraHertz to approximately 10 TeraHertz; receiving at the detector a second frequency of electromagnetic radiation, the second frequency of electromagnetic radiation transmitted through the medium within a frequency range of approximately 0.1 TeraHertz to approximately 10 TeraHertz; generating a first signal at the detector, the first signal proportional to a transmittance of the first frequency of electromagnetic radiation through the medium; generating a second signal at the detector, the second signal proportional to a transmittance of the second frequency of electromagnetic radiation through the medium; forming a ratio of the first signal and the second signal; determining one or more sets of parameters by: plotting relative humidity of the medium, absolute humidity of the medium, or water vapor concentration of the medium versus the ratio for a plurality of temperatures; and calculating a best fit function for each plurality of temperatures, thereby generating a parameter for each term of the best fit function for each of the plurality of temperatures; and using the best fit function or a lookup table at a particular temperature to determine one or more of the relative humidity, the absolute humidity, and the water vapor concentration at the particular temperature.