A new, air-filled optical fiber bundle could dramatically improve medical endoscopes. This technology could also help create endoscopes that produce images using infrared wavelengths. If so, this breakthrough would allow diagnostic procedures that aren’t currently possible.
In the Optical Society (OSA) journal Optics Letters, University of Bath (U.K.) researchers showed that these new fiber optic bundles (called air-clad imaging fibers) deliver resolution equal to the best commercial imaging fibers. And the bundles do this at twice the wavelength range of these fibers. Because of this, these air-clad imaging fibers could help create new, smaller endoscopes with even better resolutions.
HOW ENDOSCOPES WORK
Used in minor surgery and imaging, endoscopes use bundles of optical fibers to obtain images from inside the body. Light that falls on one end of the fiber bundle travels through each fiber to the far end. This process sends a picture as thousands of spots, much like pixels in a digital picture.
TESTING THE BUNDLES
Instead of using cores and claddings of two types of glass, the new bundles use an array of glass cores covered by hollow glass capillaries filled with air. These air-filled capillaries act as the fiber cladding.
To test the imaging fibers, the research team created an air-clad fiber bundle. This bundle matched the resolution of a leading commercial fiber (with the same spacing between cores). The team then stacked multiple, smaller honeycomb structures to place more than 11,000 cores into the fiber.
The researchers used the air-clad fiber bundle and the commercial fiber to image a standard test target image. And the result? The air-clad fiber performed well beyond the wavelength range that a visible camera could detect. And when the researchers switched to an infrared camera, the fiber created a clear image at twice the wavelength that the commercial fiber reached.
REAL-WORLD USE OF FIBER BUNDLES
Along with medical diagnosis and care, the new optical fiber bundles could be used for industrial applications. These uses include monitoring the contents of hazardous machines and viewing the inside of oil and mineral drills. These types of fibers are becoming more and more popular for a variety of purposes.
OFS Laboratories, one of the world’s leading optical fiber research labs, and the research arm of OFS, has performed major work in this area. The development of Microstructure Optical Fibers (MOFs) is one result of this work. The MOFs created by OFS Labs are a new class of optical fibers that are substantially different from conventional optical fibers.
Companies use optical fiber as a sensor to detect changes in temperature and pressure. This technique is often used to monitor structures including bridges and gas pipelines.
Now researchers at Ecole Polytechnique Fédérale De Lausanne (EPFL) have discovered a new method where optical fibers can identify when they are in contact with a liquid or a solid. The researchers accomplished this by generating a sound wave with help from a light beam inside the optical fiber.
A Sensor That Doesn’t Disrupt the Light
Four factors affect the light carried by a glass optical fiber: intensity, phase, polarization and wavelength. These factors can change when something stretches the fiber or the temperature varies. These changes let the fiber act as a sensor by detecting cracks in structures or temperature changes. However, until now, users could not know what was actually happening around the fiber without letting light escape, which interrupts the light path.
The method from EPFL uses a sound wave generated inside the fiber. This hyper-frequency wave regularly bounces off of the fiber’s walls. This echo varies at different locations depending on the type of material that the wave contacts. The echoes leave an imprint on the light that users can read when the beam exits the fiber. While users can study this imprint to detect and map out the fiber’s surroundings, it is so faint that it barely disturbs the light within the fiber. In fact, users could employ this technique to sense what is occurring around a fiber and send light-based information at the same time.
In experiments, the researchers submerged their fibers in water and then in alcohol, and left them out in the open air. Each time, their system correctly identified the change in the fibers’ surroundings. The group expects their technique to have many potential applications by detecting water leakage, as well as the density and salinity of fluids that touch the fiber.
Spatial and Temporal Detection
This method discerns changes in the surroundings with a time-based method. Each wave impulse is created with a slight time jag. Then, when the beam arrives, the delay is reflected. The researchers can see what any disturbances were and determine their location. The group can currently locate disturbances to within 10 meters, but have the technical means and expect to increase accuracy down to one meter.
To read and learn more, go HERE.
With the growing need to accurately monitor processes in harsh environments, optical fibers are becoming an essential element within monitoring systems, both as the communications line and as the sensing element. Optical fiber sensors have been widely adopted and used in pipeline monitoring, perimeter monitoring, heat detection and structural monitoring systems, all of which operate within the typical 45 °C to 85 °C temperature range of a standard optical fiber.
However, as industries push their sensing requirements into environments such as those found in oil wells (for downhole measurement) and nuclear reactors, there is a need for optical fibers that can tolerate these extremely high temperatures and challenging environments.
Specifically developed for harsh temperature sensing and communications environments, the new PYROCOAT K Optical Fiber is up to the challenge. This mechanically-strong fiber features an improved coating that provides excellent thermal stability, enabling wider operating temperatures than other commercially available polymer-coated fibers. In fact, the PYROCOAT K Optical Fiber provides reliable performance even when subjected to extreme, long-term, high temperature exposure. (more…)
An international research group has developed a world-first fiber optic technology which may help detect a wide range of gases with unprecedented sensitivity. Published in the journal Optica, the discovery involves the creation of a fiber optic device which consists of an invisible infrared laser coupled to an ultra-broadband supercontinuum generator – two elements that researchers have never managed to combine into a single optical system before. Led by Macquarie University scientists in Australia, the group believes that potential applications for this technology range from breath analysis to air-quality monitoring.
According to lead researcher Dr. Darren Hudson of Macquaraie University, “This new supercontinuum technology is capable of being used to detect an array of gases, including methane, carbon dioxide and nitrous oxide – gases that can be harmful to humans in high levels and have implications in climate change.”
Over the past decade, researchers around the globe have worked to create high-brightness sources of infrared light – an invisible form of light that sits just beyond visible red light in the spectrum. While this work has revolutionized how we detect and measure a staggering range of molecules, the current technology still requires large laser systems, optical laboratory conditions and an expert operator. (more…)
Interested in fiber optic sensing? If so, you’ll want to check out the “Tales From the Front Line of Fiber Optic Sensing” webinar presented by OptaSense and sponsored by the Fiber Optic Sensing Association (FOSA).
Whether it’s detecting pipeline leaks, damage to railroads or intrusion at critical facilities, fiber optic sensing plays an increasingly important role in protecting and keeping key infrastructure assets operating globally.
The webinar features fiber optic sensing installations across a wide range of industry verticals, applications and locations, including system action videos with the challenges and successes of actual deployments.
To download and view this webinar, go here.
To subscribe to the FOSA e-newsletter, go here.
If so, don’t fret. This session on “Optical Fibers for Automation Controls and Industrial Networking” is still available for viewing.
Specifically designed for integrators, this webinar discusses the challenge of transforming Industrial Automation configurations, using Industrial Ethernet, to achieve a factory floor that features a more intelligent, efficient and sophisticated network.
This session will also enhance your ability to support customers in making the most environmentally appropriate fiber optic investments.
To access and view this webinar, go HERE.
Leading experts from OFS will present six technical papers at the first-ever UL and IWCS China Cable & Connectivity Symposium in Shanghai, China, from April 25 through April 27, 2017.
These presentations will cover a wide range of subjects from acrylate-based, harsh environmental coatings for specialty optical fiber to high-speed, SWDM transmission over Wideband Multimode Fiber.
To learn more about these technical papers and the Symposium, go here.
Different applications and optical fiber types present varying requirements for fiber coatings. When specialty optical fibers are used in demanding conditions, the fibers require coatings that are sustainable when subjected to harsh circumstances.
In fact, the successful deployment of fiber in these environments can often depend far more on the fiber’s protective external coating rather than its internal optical design. Fibers may be under attack from high and low temperature ranges, excessive humidity, high pressure, aggressive chemicals, mechanical interactions or any combination of these elements.
A recent OFS white paper in NASA Tech Briefs evaluates the stability of commercially available and in-house formulated, acrylate-based coatings to help determine the optimum coating for a range of conditions. To read more, please go HERE.
The commercial use of optical fiber in harsh environments is continually growing. These applications include medical probes that undergo sterilization at elevated temperatures and distributed sensors in oil and gas pipelines and wells exposed to extreme heat and cold. For these fibers to be used successfully, researchers and manufacturers must address the issues of fiber performance and reliability under the harshest conditions.
However, current theories and knowledge on the strength and dependability of silica-based optical fiber have been based almost exclusively on experiments conducted in optical telecommunications environments. Moreover, these tests only used a relatively narrow range of temperatures. For usage in extreme environments, fiber developers and users need new data and information.
In a recent white paper from OFS Specialty Photonics, researchers describe a setup for testing the tensile strength of optical fiber when exposed to high temperatures. This paper also reports the initial results of dynamic tensile strength testing conducted on polyimide-coated optical fiber at elevated temperatures over various time intervals.
To learn more and access this white paper, CLICK HERE.
EuroWire, an international magazine covering the wire and cable industries, has featured an OFS white paper entitled “Long-Term Cable Reliability Design Criteria.”
In this paper, Dave Mazzarese, Mike Kinard and Phil Konstadinidis investigate the current requirements for allowable axial load on fiber optic cables, with a focus on overhead cables. Their findings suggest that the current criterion found in many fiber optic cable standards may be too optimistic.
To access the full article, please use this link.