Page 604 - Introduction to Information Optics

588 10. Sensing with Optics

UV pump
light source

(a)

I I i
-100 100 200 300 400

Temperature (°C)

(b)

Fig. 10.12. Illustration of fluoroptic temperature sensor, (a) Schematic of device, (b) Decay-time
of luminescent emission as a function of temperature.

changing of decay time with temperature can be used to sense the temperature.
Figure 10.12 illustrates a fluoroptic temperature sensor. A UV lamp source is
used as the means of excitation of the magnesium fluorogerminate material.
The decay time characteristics of magenesium fluorogerminate is used to sense
the measurand. To further enhance the temperature-sensing range, a combina-
tion of black-body radiation and fluorescence decay with internal cross-
referencing to enable both high and low temperature operation was also
developed, as shown in Fig. 10.13 [22]. Thus, the use of frequency-based
fiber-optic sensors is a very effective approach for wide-range temperature
sensing.