Page 419 - Sensors and Control Systems in Manufacturing

Industrial Sensors and Contr ol
Light source 373

Flexible tube
Image fiber
Light guide
Objective lens
Eyepiece

FIGURE 7.48 Basic structure of a fi ber scope.
Many examples have been reported of the application of image
fibers in process control. Image fibers are widely employed to observe
the interior of blast furnaces and the burner flames of boilers, thereby
facilitating supervisory control. Image fibers can operate at tempera-
tures up to 1000°C, when provided with a cooling attachment for the
objective lens and its associated equipment. Another important appli-
cation of the image fiber bundles is observation, control, and inspec-
tion of nuclear power plants and their facilities. Conventional image
fibers cannot be used within an ionizing radiation environment because
ordinary glass becomes colored when exposed to radiation, causing
increasing light transmission loss. A high-purity silica core fiber is well-
known as a radiation-resistant fiber for nuclear applications.
The endoscope has demonstrated its vital importance in medical
and biochemical fields such as:

• Angioplasty
• Laser surgery
• Gastroscopy
• Cystoscopy
• Bronchoscopy
• Cardioscopy

7.30 Sensor Network Architectures in Manufacturing
In fiber-optic sensor networks, the common technological base with
communication is exploited by combining the signal generating abil-
ity of sensors and the signal transmitting capability of fiber optics.
This combination needs to be realized by a suitable network topology
in various manufacturing implementations. The basic topologies for
sensor networking are illustrated in Fig. 7.49. The basic network
topologies are classified into six categories:
• Linear array network with access-coupled reflective sensors
(Fig. 7.49a).
• Ring network with in-line transmissive sensors (Fig. 7.49b ).