Specifications

Typical Applications
Fluorescence Decay Measurements
A typical experiment setup for fluorescence decay measurement is shown in Fig. 26. The sam-
ple is excited by a bh BDL-SMC picosecond diode laser [5]. The pulse repetition rate is 20,
50, or 80 MHz, the pulse width between 50 and 90 ps. The laser is operated from a simple
+12V wall-mounted power supply. The laser power is controlled by a signal from the bh
DCC-100 detector controller [3].
SYNC
Trigger Out
+12V
Detector
DPC-230 module
PMC Power supply and
DCC-100 Detector Controller
bh PMC-100
Photon
Synchronisation
ps Diode laser
A-PPI-D Pulse
Overload Shutdown
Filter
Sample
Laser Switch Box
bh BDL-SMC
Inverter
Delay
Fig. 26: Fluorescence decay measurement
The fluorescence is separated from scattered excitation light by a bandpass filter. Please note
that the optical setup is shown simplified. In practice often a monochromator is used, and the
fluorescence light is transferred to the detection system by a lens. Moreover, a polariser may
be inserted in the beam path to remove the effect of rotational polarisation from the fluores-
cence decay. Please see [1, 2] for details.
The fluorescence is detected by a bh PMC-100 PMT module. The PMT module is controlled
by a bh DCC-100 detector controller. The DCC-100 delivers the power for the PMT and the
thermoelectric cooler of the PMC-100. It also provides overload shutdown of the detector if
the light intensity becomes too high [2, 3].
The photon pulses of the PMC-100 are fed into a CFD input of the DPC-230 module. More
PMC-100 modules can be added to the system and connected to the CFD inputs number 2 and
3. A synchronisation signal from the laser is connected to CFD input number 4. It is recom-
mended that the synchronisation signal be delayed by a few meters of cable. With the right
delay, the synchronisation pulse arrives later than the pulse of a photon detected in the same
laser period. The location of the curves in the recorded time interval then becomes independ-
ent of the laser repetition rate [2].
For fluorescence decay measurement the DPC-230 is used in the TCSPC mode. It builds up a
photon distribution over the time in the laser pulse period. The typical DPC system parameters
are shown in Fig. 27. The measurement control parameters are located in the left part of the
system parameter panel. The operation mode is ‘TCSPC FIFO’, ‘Single’. The measurements
starts and stops by operator commands. If you want the measurement to stop after a specified
time, switch in ‘Stop T’, and specify the desired ‘Collection Time’.