Modular Fibre Optic Test Sets

Optical Power Measurement, Attenuation Testing, Visible Fault Location, Talk Set

Field Installable Modules:

850nm LED 1300nm LED

1310nm Laser 1550nm Laser

Visible Fault Locator Talk Set

Low Cost - Hand Held

Built in Rechargeable Batteries - Charges while Operating

High Performance - Attenuation Testing to 67dB

Retains reference at each wavelength while switched off

Stability Testing using Record and MIN/MAX functions

Calibrate without opening instrument

Governing standards
In order for various manufacturers to be able to develop components that function compatibly in fiber optic communication systems, a number of standards have been developed. The International Telecommunications Union publishes several standards related to the characteristics and performance of fibers themselves, including

ITU-T G.651, "Characteristics of a 50/125 ┬Ám multimode graded index optical fibre cable"
ITU-T G.652, "Characteristics of a single-mode optical fibre cable"
Other standards, produced by a variety of standards organizations, specify performance criteria for fiber, transmitters, and receivers to be used together in conforming systems. Some of these standards are the following:

10 Gigabit Ethernet
FDDI
Fibre Channel
Gigabit Ethernet
HIPPI
SDH
SONET
[edit]
Other uses of optical fibers
Fibers are widely used in illumination applications. They are used as light guides in medical and other applications where bright light needs to be brought to bear on a target without a clear line-of-sight path. In some buildings, optical fibers are used to route sunlight from the roof to other parts of the building (see non-imaging optics). Optical fiber illumination is also used for decorative applications, including signs, art, and artificial Christmas trees.

Optical fiber is also used in imaging optics. Bundles of fibers are used along with lenses for long, thin imaging devices called endoscopes, which are used to view objects through a small hole. Medical endoscopes are used for minimally invasive exploratory or surgical procedures (endoscopy). Industrial endoscopes (see fiberscope or borescope) are used for inspecting anything hard to reach, such as jet engine interiors.

An optical fiber doped with certain rare-earth elements can be used as the gain medium of a laser or optical amplifier.

[edit]
Fiber Optic Sensors
Optical fibers can be used as sensors to measure strain, temperature, pressure and other parameters. The small size and the fact that no electrical power is needed at the remote location gives the fiber optic sensor advantages to conventional electrical sensor in certain applications.

Optical fibers are used as hydrophones for seismic or SONAR applications. Hydrophone systems with more than 100 sensors per fiber cable have been developed. Hydrophone sensor systems are used by oil industry as well as a few countries navy. Both bottom mounted hydrophone arrays and towed streamer systems are in use. The German company Sennheiser developed a microphone working with a laser and optical fibers[5].

Optical fiber sensors for temperature and pressure have been developed for downhole measurement in oil wells. The fiber optic sensor is well suited for this environment as it is functioning at temperatures too high for semiconductor sensors.

Another use of the optical fiber as a sensor is the optical gyroscope which is in use in the Boeing 767 and in some car models (for navigation purposes).

[edit]
Manufacture
Optical fiber is made by first constructing a large-diameter preform, with a carefully controlled refractive index profile, and then pulling the preform to form the long, thin optical fiber. The preform is commonly made by three chemical vapor deposition methods: inside vapor deposition, outside vapor deposition, and vapor axial deposition.

In inside vapor deposition, a hollow glass tube approximately 40 cm in length known as a "preform" is placed horizontally and rotated slowly on a lathe, and gases such as silicon tetrachloride (SiCl4) or germanium tetrachloride (GeCl4) are injected with oxygen in the end of the tube. The gases are then heated by means of an external hydrogen burner, bringing the temperature of the gas up to 1900 kelvins, where the tetrachlorides react with oxygen to produce silica or germania (germanium oxide) particles. When the reaction conditions are chosen to allow this reaction to occur in the gas phase throughout the tube volume, in contrast to earlier techniques where the reaction occurred only on the glass surface, this technique is called modified chemical vapor deposition.

The oxide particles then agglomerate to form large particle chains, which subsequently deposit on the walls of the tube as soot. The deposition is due to the large difference in temperature between the gas core and the wall causing the gas to push the particles outwards (this is known as thermophoresis). The torch is then traversed up and down the length of the tube to deposit the material evenly. After the torch has reached the end of the tube, it is then brought back to the beginning of the tube and the deposited particles are then melted to form a solid layer. This process is repeated until a sufficient amount of material has been deposited. For each layer the composition can be varied by varying the gas composition, resulting in precise control of the finished fiber's optical properties.

In outside vapor deposition or vapor axial deposition, the glass is formed by flame hydrolysis, a reaction in which silicon tetrachloride and germanium tetrachloride are oxidized by reaction with water (H2O) in an oxyhydrogen flame. In outside vapor deposition the glass is deposited onto a solid rod, which is removed before further processing. In vapor axial deposition, a short seed rod is used, and a porous preform, whose length is not limited by the size of the source rod, is built up on its end. The porous preform is consolidated into a transparent, solid perform by heating to about 1800 kelvins.

The preform, however constructed, is then placed in a device known as a drawing tower, where the perform tip is heated and the optic fiber is pulled out as a string. By measuring the resultant fiber width, the tension on the fiber can be controlled to maintain the fiber thickness.