Mon, Sep 1, 2014 06:15
HomeMost Recent NewsLone Star Business BlogContact Us
Advertise with Texas Business
Patent: Compact Greenhouse Gas Leak Detector
Patent:  Compact Greenhouse Gas Leak Detector | sanant_txbz, Ralph Henry Hill, patent, 8134127, compact, handheld, non-laser, detector, greenhouse, gas,

Ralph Henry Hill Jr. of San Antonio received U.S. Patent 8,134,127 for “Compact Handheld Non-Laser Dectector for Greenhouse Gasses.”

Texas Business Patent of the Day:  A Bexar County man developed a convenient way to detect greenhouse gases.

Ralph Henry Hill Jr. of San Antonio received U.S. Patent 8,134,127 for “Compact Handheld Non-Laser Dectector for Greenhouse Gasses.”

Hill applied for the patent on July 29, 2011.

The patent assignee is Southwest Research Institute of San Antonio.

Hill’s invention relates to gas leak detection, and more particularly, to techniques that can be employed in compact, handheld devices for detecting leaks in relatively small spaces. 

There is presently a great need to locate leaks of so-called "greenhouse" gases such as sulfur hexafluoride.

As is generally known, higher concentrations of greenhouse gases in the atmosphere cause infrared (IR) radiation released from the earth to become trapped in the lower atmosphere. As a result of this trapped radiation, the lower atmosphere tends to warm, which in turn impacts the Earth's weather and climate. Other common greenhouse gasses generally caused by human activity include carbon dioxide (CO.sub.2), methane (CH.sub.4), chlorofluorocarbon (CFC), hydrofluorocarbon (HFC), and ozone (O.sub.3). 

In general, absorption techniques can be used to detect many such gases. However, there are a number of limitations associated with such conventional techniques. For instance, absorption techniques in the thermal IR range are not effective if the background temperature is similar to the temperature of the target gas to be detected, because there is almost no contrast between the background and the target gas. In addition, image contrast can be weak, caused by other factors, such as inhomogeneous illumination and weak absorption. Because of these problems, techniques to enhance the contrast have been proposed. 

These conventional techniques generally increase the image contrast utilizing a laser illuminator. One such technique is provided in U.S. Pat. No. 4,555,627, titled "Backscatter Absorption Gas Imaging System," which describes absorption techniques to image hazardous gases. In particular, the disclosed technique uses a flying spot IR laser beam and video imaging system, and detects hazardous gases which are highly absorbed by the laser beam. Cameras based on similar techniques have been developed to detect SF.sub.6. However, these cameras are large and bulky (typically shoulder mounted units that are coupled to power and cooling units via heavy cabling), and therefore are application limited. For instance, such techniques cannot be implemented inside confined spaces or otherwise close quarters, such as within the fuselage of an airplane or other vehicle that may be equipped with gas-containing gear (for example, radar equipment). 

There is a need, therefore, for gas leak detection techniques that can be deployed, for example, in compact, handheld devices usable for detecting leaks in space-confined applications. 

One embodiment of the present invention provides a gas leak imaging system. The system includes a non-laser incoherent light source for providing a light beam having at least one wavelength that is absorbable by a target gas, and a thermal imaging camera having a field of view and for imaging absorption of the at least one wavelength by the target gas. In general, the word "light" is used herein to include any output wavelength, such as infrared. The system is contained in a handheld housing (e.g., hand-gun or telescope shaped housing or other form factor suitable for handheld operations). The target gas can be, for example, sulfur hexafluoride (SF.sub.6), or any other detectable gas using the techniques described herein.

The camera can be, for example, a longwave infrared camera. Other targets gasses and cameras will be apparent in light of this disclosure. In some cases, the light source may be further configured for expanding the light beam toward the field of view. In one specific case, the light source is a resonance lamp, including a cell that contains a volume of a gas (e.g., such as the target gas, or other gas or combination of gasses capable of emitting radiation that is in resonance with absorption lines of the target gas), an excitation coil wrapped with a number of turns around the cell, and an excitation source operatively coupled to the coil. In response to the excitation source energizing the coil, radiation is emitted from the cell that is in resonance with absorption lines of the target gas. In one specific such case, the resonance lamp is configured with a transmitting window for expanding the light beam toward the field of view, such that radiation emitted from the cell is transmitted by the transmitting window toward the field of view. The resonance lamp may further include a rear mirror for reflecting radiation within the cell toward the transmitting window. The transmitting window can be, for example, a germanium or zinc selenide diverging lens or flat window. In another such specific case, the volume of the target gas contained in the cell is the same as the target gas. The excitation source can be, for example, one of an RF oscillator or a pulse width modulation source or an RF waveguide excitation source. In another specific case, the non-laser incoherent light source is a modified laser. The laser can be modified, for instance, by replacing its output minor with a transmitting window for expanding the beam toward the field of view, and replacing its gaseous lasing medium with a gas capable of emitting radiation that is in resonance with absorption lines of the target gas. Thus, in one such example, the CO.sub.2 of a CO.sub.2 laser could be replaced by SF.sub.6 or other suitable gas. Note that the replacement gas does not have to be the same as the target gas. Rather, the replacement gas can be any gas or combination of gasses which when excited emits a wavelength that is absorbed by the target gas. 

Another embodiment of the present invention includes a gas leak imaging method. The method includes providing a light beam from a non-laser incoherent light source to a field of view, the light beam having at least one wavelength that is absorbable by a target gas. The method further includes expanding the light beam toward the field of view, and imaging absorption of the at least one wavelength by the target gas. The light source is contained in a handheld device (for example, having a hand-gun or telescope shape) that is capable of carrying out the method. In one such embodiment, the non-laser incoherent light source is a resonance lamp that includes a cell that contains a volume of a gas (target gas, or other gas or combination of gasses capable of emitting radiation that is in resonance with absorption lines of the target gas), an excitation coil wrapped with a number of turns around the cell, an excitation source operatively coupled to the coil, and a rear minor for reflecting radiation within the cell toward the transmitting window. In response to the excitation source energizing the coil, radiation is emitted from the cell that is in resonance with absorption lines of the target gas.