Operation and Software Features (Current version: 6.1)

The TimeHarp 200 can be used in various operation modes: 

Integration mode

Measurement of the accumulated events as a function of time, manually started, stopped manually or upon overflow or expiration of a chosen collection time or upon reaching of a defined number of counts. 512 curves with up to 4096 time channels. 

Oscilloscope mode

Repetitive measurement and on-line display, very useful for optical alignment. Flicker free histogram display updates and large rate meters for work in the distance.

Operation mode f(t,T)

Continuously recording histograms without time gaps straight to disk. Acquisition time interval per histogram programmable from 1 ms to 1 s. Fast DMA transfer and a dual memory design allow continuous recording without loss of data.

Externally clocked continuous mode (imaging, scanning)

A scanner or other external hardware provides a pixel clock signal to switch to the next histogram in real-time. Data is recorded straight to disk, allowing a virtually unlimited number of pixels. Fast DMA transfer and a dual memory design allow continuous recording without loss of data.

Time-Resolved Emission Spectra (TRES)

An optional hardware and software add-on allows to control a monochromator from within the TimeHarp software, allowing automated measurement of Time-Resolved Emission Spectra. This mode drives a monochromator via a stepper motor for collection of spectrally resolved lifetime histograms. Data is collected as in standard Integration Mode and saved in different blocks of memory for each wavelength. Four different monochromator types are currently supported: Sciencetech 9030, Sciencetech 9055, Acton Research SP-2155 and Acton Research SP-275.

Time-Tagged Time-Resolved mode (TTTR) Available as an option

Continuously recording events without onboard histogramming straight to disk. Together with the channel number the arrival time of each event pair with respect to the beginning of the experiment is recorded for ultimate flexibility in offline data analysis, e.g. in single molecule detection and Burst Integrated Fluorescence Lifetime (BIFL) measurement, time-resolved FCS or Fluorescence Lifetime Imaging (FLIM). Fast transfer and a large FIFO buffer allow huge count rates without any loss of data. Up to three different external synchronization signals ("markers") can be fed into the data stream and allow to synchronize the data acquisition with external hardware (e.g. scanners).

A real-time correlator is included in the TTTR mode which can be extremely useful in setting up and monitoring of FCS experiments.

Software Overview

The TimeHarp 200 software allows the control of all measurement parameters provided by the TimeHarp 200 board. Both input triggers are programmable for a variety of signal types. All functions of the system are controlled by a software interface for Windows 2000 or XP (incl. Windows XP x64 edition). The software provides functions such as the setting of measurement parameters, display of measurement results, loading and saving of measurement parameters and measurement curves. Important measurement characteristics such as count rate, count maximum and position, and histogram width (FWHM) are displayed continuously. An automatic setup function adjusts the system to an initial optimum display range setting for the histogram. A comprehensive online help function shortens the user's learning curve. Software upgrades for extended functionality will be available with further product development.

A library (DLL) for custom Windows program development is available as an option and allows to build your own applications e.g. in LabVIEW , C++, Delphi or Visual Basic . A driver library for Linux is also available. Demo code is provided for an easy start. The libraries for Windows and Linux are API compatible, so that applications can easily be ported between the platforms.

The TimeHarp 200 permits the recording of sub-nanosecond fluorescence lifetimes, extendable to < 100 ps with reconvolution. For multi-exponential reconvolution the FluoFit software is an ideal tool. TimeHarp data can be directly exported via the clipboard.

The figure below shows measurement results from a typical fluorescent dye obtained with the TimeHarp 200. Here we used the PDL 800-B with a PLS 450 LED head for excitation and a PMA 182 for fluorescence detection. The other figure shows the data acquisition software control panel.

A typical fluorescence decay curve taken with the TimeHarp 200

To learn more about Time-Correlated Single Photon Counting and the use of the TimeHarp 200, please request our Tech Note on TCSPC.