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US 7,116,421 B2Granted
Device and method for differential sensing of hydrogen gas using thermoabsorptance or thermoreflectance
OwnerJose Agustin Garcia, Andreas Mandelis +1inventors
InventorsJose Agustin Garcia, Andreas Mandelis, Chinhua Wang
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Abstract
A hydrogen sensor, useful for trace hydrogen gas detection. The sensor involves providing a gas sample, generating modulated optical excitation sources, bringing the optical excitation source to the side of a metalized thin pyroelectric film, and detecting via a lock-in amplifier circuit the coherent differential signal resulting from thermoreflectance and thermoabsorptance changes in the film when exposed to hydrogen gas.
Claims33
An apparatus for detecting hydrogen gas comprising:
- a radiation source for generating at least two optical signals of about the same modulation frequency;
- a sensor head, comprising a pyroelectric film, the pyroelectric film including a first side coated with a hydrogen-sensitive metallic substance and a second side with a hydrogen insensitive metallic substance;
- said sensor head, comprising a pyroelectric film with a hydrogen-sensitive side, which is further overcoated with a protective coating preventing the said hydrogen sensitive metallic substance from becoming poisoned due to prolonged exposure to ambient pollutants;
- a remote optical signal transmission element for delivering from the radiation source an optical signal to the first side and an optical signal to the second side, thereby generating an essentially zero voltage or signal base line suppression across the two sides in the absence of hydrogen gas and a non-zero differential voltage in the presence of hydrogen gas;
- circuit element to generate the modulated optical excitation and detect the modulated generated differential signal;
- circuit element electronically connected to the two sides for monitoring the modulated voltage and demodulating said differential signals;
- and
- outputting said demodulated differential signals and storing said demodulated differential signals or displaying said demodulated differential signals.
5 more elements
An apparatus for detecting hydrogen gas comprising:
- a radiation source for generating a monochromatic optical signal;
- a photoelastic modulator for modulating the polarization of the optical signal;
- a sensor head, comprising a photoreflecting film, the photoreflecting film including a sensor surface coated with a photoreflecting metallic substance;
- a first optical signal transmission element for delivering from the radiation source the optical signal to the sensor surface;
- a photodetector for converting the optical signal reflected off the sensor to a photoelectric signal;
- and
- circuit element electronically connected to the photodetector for monitoring the photoelectric signal generated.
4 more elements
Dependencies are inferred from the claim text.