A dewpoint temperature sensor based on Nd/sup 3+/-doped fiber fluorescence

The design and performance characteristics of a portable dewpoint temperature sensor based on the fluorescence emission derived from an 830-nm diode-pumped, single-mode Nd/sup 3+/-doped fiber, are reported. Dewpoint temperature is measured using an optical reflectance technique at the fiber-fluorescence emission wavelength of 950 nm, where water has a local absorption maximum and substrate reflectivity exceeds 98%. The sensor exhibits a signal-to-noise ratio (S/N) of 22 dB and a dewpoint precision of /spl plusmn/0.2/spl deg/C at a fluorescence power of 5 μW.