California Lightwave Laboratories, Inc.

US Government As Represented by the Secretary of the Army

William R Lawrence

Stafford S Cooper

Bobby E Reed

John C Morgan

John H Ballard

A chemical sensor (11) including a light source (12) for producing a light flux bundle (16), an optical detector (14) for receiving a transmitted light flux bundle (24), and an absorber/expander sensor element (18) supported by a holder or support (20). Absorber/expander sensor element (18) is positioned in the space between light source (12) and optical detector (14). The absorber/expander material of sensor element (18) changes its size by either expanding or contracting in the presence of a particular chemical component. An edge (22) of sensor element (18) acts like a shutter and moves in and out of the path of travel of light flux (16), as the sensor element changes in size, which affects the intensity of light reaching and detected by optical detector (14). A method of detecting changes in the amount of a chemical analyte comprising the steps of transmitting a light flux (16) from a light source (12) past an absorber/expander (18) having a movable edge (22), exposing the absorber/expander (18) to the chemical analyte, and sensing the change in transmitted light flux (24) reaching the optical detector (14).

Chemical sensor and method

A probe device for in-situ detection of contaminants such as petroleum prcts in a subsurface media such as soil. The device comprises an elongated probe housing which is driven into the media. An ultraviolet lamp located in the housing provides excitation energy which is reflected through a UV transparent window in the housing to the media by at least one reflecting element in the housing. The reflecting element allows longitudinal offset of the lamp from the window providing space for high intensity UV lamps. A radiation receiver receives fluorescent radiation emitted from contaminants in the media transmitted through the window and provides a signal for analysis equipment on the surface. A concentrating reflector between the lamp and the housing and a focusing lens between the lamp and the reflecting element collect and focus excitation energy from the lamp. A filter between the lamp and the first reflecting element filters unwanted wavelengths from the excitation energy and a filter between the window and radiation receiver filters unwanted wavelengths from the radiation receiver. A calibration receiver is positioned in the optical path to receive excitation energy just before exiting the window. The design improves sensitivity, especially for POL contaminants and eliminates the need for complicated excitation equipment at the surface.

Probe device for detecting contaminants in subsurface media

A method and apparatus for detecting the presence of hydrocarbon analyte in at least one of a liquid and vapor state. The apparatus (21) includes an optical fiber (22), an absorber-expander (31) mechanically coupled (32) to the optical fiber (22) to produce a change in transmission of light along the fiber (22) upon absorption of the hydrocarbon (33). The absorber-expander (31) is selected to absorb hydrocarbons, but not water, and to be capable of multiple reversible expansion and contraction cycles without significant structural degradation. Methyl terminated, silica and iron oxide filled, dimethyl polysiloxane provides a material which will experience substantial swelling in the presence of a hydrocarbon and yet is substantially reversible on desorption of the hydrocarbon from the absorber-expander (31). The method includes positioning an optical fiber (22) having such an absorber-expander (31) for absorption of hydrocarbons and detecting the decrease in light transmission produced by expansion of the absorber-expander (31), for example, by one of microbending and axial misalignment. The location of the absorber-expander (31) along strand (22) can be determined by optical time domain reflectometry or by digital sensing nodes (122), and multiple couplings (57) and biasing couplings (153) for mounting the absorber-expanders (152) to the optical fiber (151) can be used to enhance sensitivity.

Growing community of inventors

Dickinson, TX, United States of America

William R Lawrence