Page 71 - Sensors and Control Systems in Manufacturing
P. 71
4000 The Role of Sensors in the 21st Century 33
3000
Intensity (counts) 2000
1000
0
400 500 600 700
Wavelength (nm)
FIGURE 1.17 Spectrographic analysis of a 5-mm non-phosphor white LED.
(See also color insert.)
4000
3000
Intensity (counts) 2000
1000
0
400 500 600 700
Wavelength (nm)
FIGURE 1.18 Spectrographic analysis of a 10-mm non-phosphor warm white
LED. (See also color insert.)
1.15.1 Luminous Flux
The luminous flux is the time rate of the flow of light. The unit of
measure is the lumen. One lumen may be defined as the light flux
emitted in a one-unit solid angle by a one-candela uniform-point
source. The lumen differs from the candela in that it is a measure of
light flux irrespective of direction. The lumen is used to express a
quantity of light flux: total output of a source; output within a specific
