Pulse Measurement of Fluorescence Lifetime

The common feature of the schemes in this category is that the excitation light applied to the fluorescent material is a high intensity delta function pulse (e.g., a laser pulse or that from a flash lamp) or an rectangular pulse, and the measurement is derived from the observation of the fluorescence decay after the removal of the excitation light. The following are the outlines of some typical schemes which are of this type and have been used in thermometry applications. 

Timing circuits are provided for measuring precisely the time between ti and t. That time difference can be correlated directly with the temperature of the fluorescent sensor by reference to an empirically determined look up table stored digitally within the instrument. 

This two-point measurement technique is used in the system reported by Wicker-sheim and Sun,(27) where a lamp phosphor, tetravalent manganese-activated magnesium fluorogermanate, mentioned above, is used as fluorescent sensor. The excitation 

Another example is the balanced integration method described by Sun.(29) This technique is designed to achieve 0.01°C resolution using tetravalent manganese-activated magnesium fluorogermanate, the same sensor material that has been used 

The result of a number of curve fits are averaged to further reduce the effects of noise. The averaged decay time is then compared with values stored in adigital look-up table to determine the temperature of the sensor. 

---