The PicoHarp 300 is a high-end, easy-to-use, plug and play Time-Correlated Single Photon Counting (TCSPC) system. It is connected to a PC through a state of the art USB 2.0 high speed interface. A new design approach provides identical and synchronized but independent input channels. They can be used as detector inputs for coincidence correlation experiments or as a pair of start and stop inputs for TCSPC. It allows a forward start-stop operation even at full repetition rate of mode locked lasers with stable repetition rate up to 84 MHz. Experiments with low repetition rate benefit from the PicoHarp's multi-stop capability. The design allows high measurement rates up to 10 million counts/sec and provides a highly stable, crystal calibrated time resolution of 4 ps. This time resolution is well matched to the SPADs of the PDM series or micro-channel plate photomultiplier tubes (MCP). Overall IRF widths down to 50 ps can be achieved with pulsed diode lasers. With short pulsed lasers such as Ti:Sapphire lasers IRF widths as short as 30 ps can achieved. Both input channels are equipped with constant fraction discriminators (CFD), sensitive on the falling edge.

A Time-Tagged mode for recording of individual photon events with their arrival time on both channels is available as an option, allowing the most sophisticated offline analysis of the photon dynamics. TTTR data can be correlated in real-time for monitoring of FCS experiments at count rates up to 500.000 counts/sec. External marker signals can be used to synchronize the device with other hardware such as scanners e.g. for Fluorescence Lifetime Imaging (FLIM). In the TTTR mode, the PicoHarp 300 can also be used as a generic event timer, e.g. for Satellite Laser Ranging (SLR).
As accessories external routers such as the PHR 800 for connection of up to four detectors are available. External hardware such as monochromators can be controlled via CAN or serial bus (currently supported: Sciencetech 9030, Sciencetech 9055, Acton Research SP-2155 and Acton Research SP-275).

The PicoHarp software for Windows provides functions such as the setting of measurement parameters, display of results, loading and saving of measurement parameters and measurement curves. Important measurement characteristics such as count rate, count maximum, position and peak width are displayed continuously. A comprehensive online help function shortens the users' learning curve. A library for custom programming e.g. with LabVIEW is also available as an option. Software upgrades for extended functionality will be available with further product development.

Measurement data from the PicoHarp 300 can be analysed by different software packages. For multi-exponential reconvolution the FluoFit software is an ideal tool. For the analysis of TTTR data (e.g. FLIM, FCS, FLCS, FRET, BIFL, etc.) the SymPhoTime software suite is the program of choice.

• Integration mode
• Oscilloscope mode
• Time-Resolved Emission Spectra (TRES)
• Time-Tagged Time-Resolved mode (listing each event pair arrival time)*
• On-line ("real-time") correlator for FCS*

* available as an option

Current software and Developer's Library version: 2.3

The new software version features an improved online ("real-time") - correlator for FCS that now also supports the T2 mode. The maximum measurement time in histogrammer mode has been extended to 100 hours and the software now includes an indicator for critical measurement conditions such as pile-up or incorrect divider settings. Owners of previous versions receive a free update upon request.