Optical Hydrogen Sensor Research Articles

Enhanced optical detection of hydrogen using the excitation of surface plasmons in palladium

The generation of a surface plasmon wave at a palladium interface is used in the design of an all optical hydrogen sensor. Large (>90%) changes in reflected light intensity from the sensor element are observed when the sensor is exposed to hydrogen concentrations corresponding to percentage levels. This is a ten-fold enhancement of the reflectivity change observed in sensors using normal reflection from palladium.

Laser Raman sensor for measurement of trace-hydrogen gas

A new optical hydrogen sensor based on spontaneous Raman scattering of laser light has been designed and constructed for rugged field use. It provides good sensitivity (better than 100 parts in 10(6)), rapid response (several seconds), and the inherent Raman characteristics of linearity and background gas independence of the signal. Efficient light collection and discrimination by using fast optics and a bandpass interference filter compensate for the inefficiency of the Raman-scattering process. A multipass optical cavity with a Herriott-type configuration provides intense illumination from an air-cooled cw gas laser. The observed performance is in good agreement with the theoretical signal and noise level predictions.

Optical fiber hydrogen sensor

A new type of hydrogen sensor is reported in which an optical fiber is used as the sensing element. The fiber is coated with palladium which expands on exposure to hydrogen. This changes the effective optical path length of the fiber, which is detected by interferometric techniques. Preliminary experiments have demonstrated the effect and suggest a high sensitivity and a wide dynamic range for this kind of sensor. The experimental results are compared to calculated optical path length changes. Application of this kind of sensor to the detection of other chemicals appears feasible.