Fiber optic technology and its applications have progressed rapidly in the
last 30 years. They are low cost and have the capability of carrying
information from one place to another, and are immune to the many interferences
that afflict electrical and wireless communication mediums. This has enabled
fiber optics to replace older technologies and play a key role in the fast and
strong growth in worldwide communications in the last 25 years.
The replacement of older technologies to fiber optics can be attributed to
the many advantages fiber optic technology offers, including:
·
Insensitive to EMI, RFI, and EMP
·
Does not radiate energy
·
Low transmission losses
·
Wide transmission bandwidth
·
Unaffected by lightning
·
Lightweight
·
Non-corrosive
·
Absolutely safe in explosive
environments
·
Flexible in upgrading
·
Immune to ground loops
·
Secure, cannot be tapped without
detection
Fiber-optic sensors are a powerful class of sensors, bringing to
measurement systems many of the advantages that optical-fiber technology has
brought to the telecommunications industry. Three main characteristics
differentiate fiber-optic sensors from other types of sensors: A) A high
bandwidth of optical fibers allows them to convey a large amount of measurand
information through a single fiber; B) The optical fiber is a dielectric, it is
not subject to interference from electromagnetic waves that might be present in
the sensing environment; and C) Fiber-optic sensors can function under adverse
conditions of temperature and pressure and toxic or corrosive environments that
can erode metals at a rapid rate, have little effect on optical fibers. In
addition, fiber-optic sensors are intrinsically safe in explosive environments
(no sparks), lightweight, compact, robust and potentially inexpensive.
Therefore, useful as sensing devices for a wide range of physical and chemical
applications including chemical, temperature, strain, biomedical, electrical
and magnetic, rotation, vibration, displacement, pressure and flow.
Many of these categories were developed by military organizations during
the past decade. These military sensors, while extremely effective at creating
"smarter" structures, have not found large commercial markets, with
only a few exceptions. These exceptional markets include: chemical sensing
(especially in the petrochemical industry), transportation, building and
structural monitoring and biomedical. The first three segments represent nearly
all of the existing market and the fourth represents an explosive market
waiting for proven, noninvasive technologies.
Figure 1 provides the revenue forecasts for fiber optic pressure sensors
for North America for the years 2000-2006.
In 1999, the total revenues for fiber-optic pressure sensor sales in North America totaled $14.5 million. This was an
approximate 5.5 percent growth from the previous year’s sales of $13.7 million.
It is anticipated this trend will continue for the forecast period (2006) of
this report, with growth rates accelerating from 2003 to 2006.
Fiber-optic sensors can perform the functions of virtually any
conventional sensor, often faster and with greater sensitivity, they can also
perform measurement tasks that would be impracticable with conventional
sensors. For instance, in building and structural monitoring, fiber-optic
sensors can be embedded in structures such as airplanes and bridges,
continuously reporting on structural integrity and possibly averting a
catastrophic failure.
Fiber Optics and Telecommunications
The telecommunications industry was primarily responsible for the
development of fiber optic sensor technology in the1980s. In spite of their
special capabilities, the general acceptance of fiber optic sensors has been
slow. The challenges of performance, cost, modularity and standardization all
limited penetration to industrial applications. However, in the past few years
that has started to change as companies educate the public to the benefits of
optical sensing in their quest for a larger part of the sensor market--a market
certainly worth pursuing. Indeed, for an indefinite period, electronic sensors,
which are well supported by electronic signal-handling methods and hold
established positions in control systems, are expected to coexist with
fiber-optic sensors. But electronic signal-handling methods can serve
fiber-optic sensors because optical signals readily convert into electronic
form. In the longer term, all-optical signal-handling methods will become
available, complementing and extending the capabilities of fiber-optic sensors.
The numerous advantages of fiber-optic sensors will ensure they continue
to attract research funding for further development. The maturation of
fiber-optic technology will, over time, expand the applications of fiber-optic
sensors as the cost of components such as laser sources and single-mode
couplers decline and smart technology improves. Furthermore, with the drive
toward automation by manufacturing facilities all over the world, the many
inherent advantages of fiber-optic sensors promise a major role for them in the
future.
Emerging Fiber-Optic Applications
Since its discovery as a communications medium in 1966, fiber optics,
transmitting or guiding light through the core of a flexible hair-thin glass
strand, has become the primary interest in the telecommunications community. As
demand for ever-higher bandwidth continues, researchers continue to design
faster fiber-optic communications systems. Although the communications market
for fiber optics of some $7 billion dominates fiber-optic applications, several
non-communications applications are emerging. Among those applications are the
fiber-optic delivery of electric power (power by light), fly-by-light control
of aircraft, fiber-optic delivery in laser welding, use of fiber optics for
illumination fiber-optic sensing of parameters such as temperature, chemical
constituency and strain in physical structures.
Figure 2 provides the percentage of revenue forecasts for the fiber-optic
pressure sensors market in North America for
the years 2000-2006 by end-user industry.
According to industry participants, fiber optic sensing technology shows
that light can provide the same, if not better, response than other
conventional sensing systems--sometimes many times faster and more accurate.
However, many in the industry attest to the fact that being able to do
something and do it well does not always guarantee monetary success. Economies
of scale, which relate to higher prices versus conventional techniques, and a
lack of understanding among application engineers who must work with sensors
everyday are some of the hurdles companies face on the road to success. Despite
all this, fiber optic sensors are making inroads in hazardous-environment,
environmental monitoring and other fields that will lead to further success
with this technology.
