Fiber Optic Sensors for Borehole seismic technology system

Seismic techniques are the main techniques for the characterization of subsurface structures and stratigraphy. Borehole technology system provides the highest resolution characterization and most precise monitoring results because it generates a higher signal to noise ratio and higher frequency data than surface seismic techniques. A new generation of fiber optic borehole sensor systems has been developed based on all fiber optic data transmission and fiber optic sensor technologies. The new fiber sensors are much more sensitive and are able to record much larger bandwidth data with better vector fidelity than is possible with current seismic sensor technologies. The new sensors also can operate in most hostile environments found in boreholes such as pressure and temperature conditions. This improvement in data quality and density will generate better images and more precise monitoring results, which will allow a much improved high-resolution interpretation and ultimately better oil and gas production.

Since the borehole seismic system does not require electric power for either the optical sensors or the hydraulically operated deployment system, the entire system is intrinsically safe. The fiber-optic seismic sensor system measures the strain of the fiber between two Fiber Bragg gratings surrounding the mandrel using an interferometric measurement technique comparing the phase angle between two spaced reflections from the same light pulse traveling in the fiber. It is using a time-division multiplexing technique to transmit the dynamic fiber strain information to the interrogators. This allows the measurement of extremely small strains in the fiber. The fiber optic seismic sensor is self-standing to electric and electromagnetic interference in the borehole since the system does not require any electronics at the fiber optic sensor end. This design also makes the fiber optic seismic sensor extremely robust and able to operate in extreme environments such as temperatures up to 300 C.  All the sensors are calibrated so the optical output amplitude into absolute acceleration can be mapped. The sensors have also proved to be about 100 times more sensitive than the regular coil geophones that are used in borehole seismic systems today.

Optromix Company manufactures a wide range of sensors, that are able to feel the slightest deformation of the structures.

Medical fiber optic sensing products and technologies

The range of medical devices incorporating optical fibers has taken a slow technological growth, with the bulk of the industry focused on endoscopy and various methods of optical power delivery for cutting, dissecting, and ablating. These technologies utilize an optical fiber’s mechanism—the ability to guide light from one location to another.

Fiber sensing technologies offer significantly advanced functionality by utilizing their inherent sensitivity to temperature, strain, and pressure. During the last five years, the medical industry has taken significant steps to adapt historic fiber-optic sensing methods to enable them to be used within in vivo environments.

The main area for recent technological developments driving fiber sensors into the medical industry has focused on minimally invasive surgery (MIS). The benefits of MIS are now well-founded, encouraging surgical-tool manufacturers to invest their money in new technology developments to pioneer new MIS procedures or to further improve existing procedures. Three exciting recently developed fiber optic sensing technologies for MIS are focused on here: haptic feedback, 3D shape sensing, and pressure sensing.

By utilizing multiple FBGs or manipulating the FBG structure, it is possible to obtain a spatially distributed strain profile. Such FBGs can be applied along the length of a surgical tool to enable haptic feedback at the regions of most concern. A prime example of this is to add haptic sensing to a grasping tool, where both the grasping and spreading forces can be measured and fed back to the surgeon to indicate how tightly they are grasping or how much force they are applying to pry tissues apart.

Fiber optic 3D shape sensing has been developed by several commercial groups to enable a dramatic reduction in the need for prolonged exposure to the visualization methods, as the optical fiber can track itself in three dimensions and thus if laid within a catheter, can recreate the shape of the catheter. This technique relies on a mixture of FBG and fiber technology, where a very special fiber has been developed specifically for this application. Optical fibers also can be optimized to be sensitive to the hydrostatic pressures experienced within the body. These new applications are being opened up by a mixture of economic desire and technology development. Specialty optical-fiber manufacturers continue to pioneer new fiber designs that medical-device manufacturers can exploit. This enables a greater diversification of medical-device product ranges and opens up new procedures that were not previously possible with minimally invasive surgery.