Page 224 - Sensors and Control Systems in Manufacturing

Fiber Optics in Sensors and Contr ol Systems
As speed and transmission distance increase, the problems caused by 185
electromagnetic interference, radio frequency interference, cross talk,
and signal distortion become more troublesome. In terms of signal
integrity, just as in computer-integrated manufacturing data acquisi-
tion and information-carrying capacity, fiber optics offers many advan-
tages over copper cables. Furthermore, optical fibers emit no radiation
and are safe from sparking and shock. These features make fiber optics
the ideal choice for many processing applications where safe operation
in hazardous or flammable environments is a requirement.
Accordingly, fiber-optic cables offer the following advantages in
industrial applications:

• Wide bandwidth
• Low attenuation
• Electromagnetic immunity
• No radio frequency interference
• Small size
• Light weight
• Security
• Safety in hazardous environment

3.19.1 High-Clad Fiber-Optic Cables
Large-core, multimode, step-index high-clad silica fiber-optic cables
make fiber-optic technology user-friendly and help designers of sen-
sors, controls, and communications realize substantial cost savings.
The coupling efficiency of high-clad silica fibers allows the use of less
expensive transmitters and receivers. High-clad silica polymer tech-
nology permits direct crimping onto the fiber cladding. Field termi-
nations can be performed in a few minutes or less, with minimal
training. The following lists describe the structure and characteristics
of several fiber-optic cables used in industry.
Simplex fiber-optic cables (Fig. 3.66) are used in:
• Light-duty indoor applications
• Cable trays
• Short conduits

FIGURE 3.66 Simplex fi ber-optic cable.