Image of Flex01-12. The dimension of the external enclosure is approximately
3.25x2.5x0.8".
Functions:
Flex01-12 is a photon counting digital hardware that can be used as
- Single high resolution real time MT-64 multiple tau digital correlator (AxA or
AxB). Minimum sample time 12.5ns.
- One channel photon history recorder. System clock speed: 60MHz. Average intensity
limit: 910KHz
In photon correlation mode, it calculates the correlation function(s) in real time
covering delay times from the 12.5ns to about an hour.
In photon history recorder mode, it records the time between successive photon
events. This is measured by counting the number of ticks of the system clock between
the photon events. This time is then transferred to the host personal computer via
high speed Universal Serial Bus (USB). The amount of information to be transferred
is proportional to the count rate of the incoming photons. Using a lossless
compression technique, Flex01-12 transfers complete time series without gaps for average
count rate from 0 to approximately 910 kcps in one channel mode. At high count rates
the overflows are displayed in real time.
Flex01-12 hardware specifications:
- Input signal: standard TTL pulses.
- Two BNC connectors
- One USB connector.
- Easy to use FlexWindows software and software for Windows98 libraries included.
Correlation mode specifications:
1. Single MT-64 multiple tau channel layout ( sample time denoted at T, data width
W):
- Auto/cross correlations.
- 12.5 ns minimum sample.
- 1088 real time channels.
- Delay time range: 12.5ns to 1 hour in multiple tau channel layout.
- First 64 channels: T = 12.5ns, W = 1 bits, delay times T to 64*T;
- Second 32 channels: T = 2*12.5ns, W = 2 bits, delay times 66*T to 128*T
- Third 32 channels: T = 4*12.5ns, W = 3 bits, delay times 66*T to 128*T;
- Fourth 32 channels: T = 8*12.5ns, W = 4 bits, delay times 66*T to 128*T;
- Sample time doubles every 32 channels and data width increment 1 bit to prevent
overflow.
- The longest delay time is about one hour.
2. Single photon history recorder mode specifications:
- System clock: 60 MHz in one channel mode.
- 16.7 ns pulse pair resolution.
- Complete time series recorded on a PC hard drive for average count rate up to 910 KHz in
one channel mode. The maximum count rate is somewhat host PC dependent.
More about multiple tau theory.
Multiple tau theory was invented by Klaus Schätzel. The following papers discuss
the theory and the advantage of the multiple tau scheme.
- Klaus Schätzel. Single Photon Correlation Techniques. Dynamic Light
Scattering: The method and some applications, Edit by Wyn Brown, Clarendon Press, Oxford,
P 76, 1993.
- Klaus Schätzel et. Noise on Multiple-Tau Photon Correlation Data.
SPIE Vol. 1430, P109, Photon Correlation Spectroscopy: Multicomponent Systems,
1991.
- Klaus Schätzel. New Concept in Correlator Design. Inst. Phys. Conf. Ser. No.
77, P175, 1985.
- Klaus Schätzel et. Photon Correlation Measurements at Large Lag
Times. Journal of Modern Optics, Vol. 35, No. 4, P711, 1988.
