Image of Flex5000/FAST and with a notebook computer. The dimension of the external enclosure is 2.5"x2.75"x0.8".
Functions:
Flex5000/FAST is a digital correlator that can be used as
1. Fast real time multiple tau digital correlator. Minimum sample time 12.5ns.
2. Dual real time multiple tau digital correlator. Minimum sample time 400ns.
Flex5000/FAST 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 multiple tau channel layout ( sample time denoted at T, data width W):
- Auto/cross correlations.
- 12.5 ns minimum sample.
- 288 real time channels.
- Delay time range: 12.5ns to 1 hour in multiple tau channel layout.
- First 16 channels: T = 12.5ns, W = 1 bits, delay times T to 16*T;
- Second 8 channels: T = 2*12.5ns, W = 2 bits, delay times 9*T to 16*T
- Third 8 channels: T = 4*12.5ns, W = 2 bits, delay times 9*T to 16*T;
- Fourth 8 channels: T = 8*12.5ns, W = 3 bits, delay times 9*T to 16*T;
- Sample time doubles every 8 channels and data width increment 1 bit to prevent overflow.
- The longest delay time is about one hour.
Intensity limits:
Flex5000/FAST is designed with sufficient hardware resource to prevent overflow at any reasonable intensities. However, in extreme situations, clipping and overflow could happen. The intensity limits are following:
- Maximum intensity integrated over 50ns: 60 MHz. Overflow will happen if the input intensity exceeds the maximum.
- Maximum intensity integrated over 168ms: 28.3MHz. Overflow will happen if the maximum is exceeded.
2. Dual multiple tau channel layout ( sample time denoted at T, data width W):
- Dual auto correlations.
- 400 ns minimum sample.
- 256x2 real time channels.
- Delay time range: 267ns to 1 hour in multiple tau channel layout.
- First 16 channels: T = 400ns, W = 4 bits, delay times T to 16*T;
- Second 8 channels: T = 2*400ns, W = 5 bits, delay times 9*T to 16*T
- Sample time doubles every 8 channels and data width increment 1 bit to prevent overflow.
- The longest delay time is about one hour.
Intensity limits:
Flex99R-12D is designed with sufficient hardware resource to prevent overflow at any reasonable intensities. However, in extreme situations, clipping and overflow could happen. The intensity limits are following:
- Maximum intensity integrated over 400ns: 37.5 MHz. Clipping will happen if the input intensity exceeds the maximum.
- Maximum intensity integrated over 168ms: 28.3MHz. Overflow will happen if the maximum is exceeded.
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.