Page 362 - Sensors and Control Systems in Manufacturing

Advanced Sensors in Pr ecision Manufacturing
The camera sensor would operate at wavelengths from 500 to 317
1100 nm. The angular resolution would be about 0.5°. In the case of an
effective aperture of f/3, the camera would provide an unvignetted
view over the middle 161° of the strip, with up to 50 percent vignett-
ing in the outermost 9.5° on each end.
The decentration of the spherical reflecting surface is necessary
to make room for the optical fibers and the structure that would
support them. On the other hand, the decentration distance must
not exceed the amount beyond which the coma that results from
decentration would become unacceptably large. In the case of an
effective aperture of f/3, the coma would be only slightly in excess
of the spherical aberration if the decentration were limited to about
f/6. This would be enough to accommodate the fibers and support-
ing structure.

6.28 Optical Sensor Quantifying
Acidity of Solutions
With environmental concerns increasing, a method for taking effec-
tive measurements of acidity will minimize waste and reduce both
the cost and the environmental impact of processing chemicals. Sci-
entists at Los Alamos National Laboratory (LANL) have developed
an optical sensor that measures acid concentration at a higher level
than does any current device. The optical high-acidity sensor, reduces
the wear generated from acidity measurements and makes possible
the economic recycling of acid waste.
The high-acidity sensor (Fig. 6.30) consists of a flow cell (about
87.5 mm across) in which two fused silica lenses are tightly mounted
across from one another. Fiber-optic cables connect the two lenses to
a spectrophotometer. One lens is coated with a sensing material con-
sisting of a polymer that is chemically bound to the lens and an indi-
cator that is physically entrapped with the polymer. Acidic solutions

FIGURE 6.30
Optical high-acidity
sensor.