qutools quTAU, Руководство пользователя

Страница: 34 / 44

11 HISTOGRAMS
11.2 Start-Multistop Histograms: Lifetime Measurements
Please note that this feature is only optional for quTAU devices with the hardware upgrade
and part of the software extension quTAU (H+).
In contrast to the single-stop histograms discussed above, all STOP events (not only the
first one) following a given START event are used to calculate time differences and make
up the histogram. Therefore, this method is perfect for lifetime measurements.
11.2.1 Model functions
The most commonly used models for lifetime measurements are exponential decay , double
exponential decay , and the Kohlrausch decay function .
Standard: Exponential Decay
f
1
( t ) = I
0
·
e
−
t/τ
0 (1)
Double Exponential (FLIM-FRET)
f
2
( t ) = I
0
α
·
e
−
t/τ
0 + (1
−
α )
·
e
−
t/τ
1 (2)
Kohlrausch Decay Function, Stretched Exponential
f
3
( t ) = I
0
·
e
−
( t/τ
0
)
β
(3)
11.2.2 Realization in the quTAU GUI
Lifetime Measurements can be obtained and analyzed in the quTAU GUI, see Figure 23 .
Additionally, the data can be fitted to one of the models explained above. For testing
purposes or if no device is connected, data can also be simulated (and analyzed normally).
Settings can be accessed on the bottom, the retrieved data are shown in the plot at the
top.
11.2.3 DLL Usage
Table 10: Examples: Lifetime Measurements
LabView Example
/userlib/labviewXX/examples/lifetime.vi
C Example
/userlib/src/example5.c
The quTAU software assists in lifetime measurements. The work flow can be seen in the
LabVIEW
TM
example
lifetime.vi
(see Figure 24 ). The lifetime feature is optional, use
TDC checkFeatureLifeTime
to check for its availability.
www.qutools.com quTAU/quPSI Manual V4.0 Page 34