PC Based Photon Counting Systems

Introduction

Based on a wide variety of photon counting modules Becker & Hickl delivers ready-to-use systems which contain one or more photon counting modules. Furthermore, combinations of different modules are available, and a step motor controller for experiment control can be added. Some examples for complex systems are described in this application note.
The following photon counting modules are available:

Time-Correlated Single Photon Counting Modules
Recording of light pulses with a resolution down to 25 ps FWHM
Time-Resolved Spectra with 25 ps Resolution
Multi Detector Capability
Short Measurement Times due to high Count Rates
Optical Oscilloscope Capability
Large Memory Versions for Image Scanning, Lifetime Imaging and Optical Tomography
Versions for Fluorescence Lifetime Measurement of Single Molecules
Gated Photon Counting Counters and Multiscalers
Up to 800 MHz Count Rate
Multiscaling down to 250 ns / Channel
Ultra-Low Background Count Rate by Gated Detection
Steady State and Pulsed Emission Spectra
Event Recording for Single Molecule Detection
Bioluminescence Measurements
Multichannel Photon Counters
Up to 32 Parallel Detector Channels with 100 MHz Count Rate
Fast Multiscalers down to 5 ns / Channel
Luminescence Decay Measurements from ns to Seconds
Ultra-Fast Acquisition, High Repetition Rates
Time-of-Flight Measurements
Step Motor Controllers
Monochromator Control and Sample Scanning
Detectors and Preamplifiers
PMT-Modules with internal HV Supply
Ultra-Fast MCPs for TCSPC
Preamlifiers with Detector Overload Detection
Photodiode Modules for Gating and TCSPC Triggering

Time-Correlated Photon Counter with Step Motor Controller

A typical TCSPC (time-correlated single photon counting) system is shown in the figure below. It contains a time-correlated photon counting module (SPC-3, SPC-4 or SPC-5 module) and a step motor controller STP-240.

To achieve maximum time resolution, an MCP is used as detector. If maximum time resolution is not required, a PMH-100 detector is used. This is a rugged and easy-to use, but fast PMT module which is powered directly from the photon counting module. A fast photodiode modules is used to synchronise the SPC module with the light source. Both the PMH-100 and the photodiode module are powered directly from the SPC module.

Typical applications of the system shown above are:
Measurement of fluorescence decays or other optical waveforms down to 25 ps. Due to the high count rates (8 MHz for SPC-4-versions) extremely short measurement times are achieved.
Measurement of decay data of single Molecules (SPC-4-Versions). Fluorescence decay data are collected for single molecules running through a capillary. Depending on the SPC module version, the data is stored as a set of subsequent decay curves in time intervals down to 1 ms or as independent information for each individual photon.
Measurement of subsequent decay curves with wavelength stepping. The full time and wavelength dependence of the sample is recorded as a set of decay curves for subsequent wavelengths.
Measurement of decay curves with spatial scanning of the sample. The spatial dependence of the sample emission is recorded set of decay curves for subsequent sample points. With the SPC-5-versions up to 16384 decay curves can be recorded in one measurement.
Measurement of subsequent decay curves in programmed time intervals. The variation of a sample with the time is recorded as a set of subsequent decay curves.
Recording of time-resolved spectra in time windows down to 25 ps. Up to eight spectra are recorded simultaneously for the same sample in different time windows.
Optical Oscilloscope Applications. All SPC modules provide an ‘Oscilloscope Mode’ which displays subsequently measured waveforms in intervals down to some 10 ms. Thus, optimising and adjusting your measurement setup is not longer a trial-and-error procedure.

Gated Photon Counter / Multiscaler with Step Motor Controller

A typical Gated Photon Counting system is shown in the figure below. It contains a gated photon counter (PHC-322) or a gated photon counter / multiscaler (PMS-300) and a step motor controller.

To detect the light signals, one or two PMH-100 detectors are used. These are rugged and easy-to use, but fast PMT module which are powered directly from the photon counting module. One or two fast photodiode modules are used to gate the PMS or PHC. As the PMH-100, the photodiode modules are powered from PMS or PHC module. Typical applications of the systems shown above are:

Steady state emission spectra. The high count rate of 800 MHz yields an exceptional high linearity up to extremely high peak intensities.
Sample scanning. The emission of the sample is recorded as a function of the position of the measured spot.
Steady state emission spectra with pulse excitation and gated detection. The gating reduces the detector background counts the extremely low values.
Luminescence decay curves in the us range (PMS-300). The high count rate of the PMS (800 MHz) allows to record more than 200 events for each channel in one sweep. Accumulation of several sweeps is free of dead time, therefore an extremely high repetition rate is achieved.
Time-of-flight measurements with a resolution down to 250 ns (PMS-300). The high count rate of the PMS (800 MHz) allows to record more than 200 events for each channel in one sweep. Accumulation of several sweeps is free of dead time, therefore an extremely high repetition rate is achieved.
Detection of single molecule or other particles (PMS-300). The ‘Event Mode’ of the PMS-300 allows the recording of events like the transition of a single molecule or another particle through a laser focus. The background counts are suppressed by an adjustable ‘Event Threshold’.

16 Channel Photon Counter / Multiscaler with Step Motor Controller

For application which require a high number of detector channels the PMM-328 Eight-Channel Photon Counter has been designed. A system with this device is shown in the figure below.

As a detector for the PMM-328 usually the R5900 from Hamamatsu is used. This is a PMT with 16 independent channels delivering one output signal each. The R5900 is available in a 1x16 and in a 4x4 configuration. To record the photons detected by the 16 PMT channels two PMM-328s are required. Again, a step motor controller STP-240 is included for monochromator control and sample scanning.

The applications of the system shown above are similar to these of the PHC / PMS system. However, due to the high number of counter channels the system has some interesting features:

Simultaneous measurement of 16 waveforms. The PMM system records one waveform for each channel of the R5900. This can be used to investigate a sample at several wavelengths or at several points.
High efficiency sample scanning. 16 adjacent lines of a samples can be scanned simultaneously.
Multi-photon counting. A usual single channel photon counter can detect only one photon within its response time or within the response time of the detector. The system above can detect 16 photons at the same time - a stunning feature for a photon counter. To achieve multi-photon counting it is only required that the light is spread over all 16 channels of the R5900 and the results of the 16 counter channels are added.

32 Channel Photon Counter / Multiscaler

Up to four PMM-328 Eight-Channel Photon Counters can be combined in one system and operated with the same software.

With two R5900 PMTs or with a 32 channel PMT a 32 channel photon counting system can be built up. Systems of this type are used to simultaneously record up to 32 waveforms or to count several photons which appear simultaneously within the detector response time.

Combined Time-Correlated and Gated Photon Counter

An extremely versatile system is shown in the figure below. It contains a time-correlated photon counting module (SPC-3, SPC-4 or SPC-5 module), a gated photon counter (PHC-322) or gated photon counter / multiscaler (PMS-300) and a step motor controller. The step motor controller is used both by the SPC and by the PMS / PHC module software.

To achieve maximum time resolution with the TCSPC part, an MCP is used as detector. For the Gated Photon Counting and Multiscaling part a PMH-100 detector is used. This is a rugged and easy-to use, but fast PMT module which is powered directly from the photon counting module. Two fast photodiode modules are used for the synchronising of the SPC module and for gating the PMS or PHC. As the PMH-100, the photodiode modules are powered from the SPC and PMS or PHC modules.
The system can be used for

Measurement of fluorescence decays or other optical waveforms down to 25 ps. Due to the high count rates (8 MHz for SPC-4-versions) extremely short measurement times are achieved.
Measurement of decay data of single Molecules (SPC-4-Versions). Fluorescence decay data are collected for single molecules running through a capillary. Depending on the SPC module version, the data is stored as a set of subsequent decay curves in time intervals down to 1 ms or as independent information for each individual photon.
Measurement of subsequent decay curves with wavelength stepping. The full time and wavelength dependence of the sample is recorded as a set of decay curves for subsequent wavelengths.
Measurement of decay curves with spatial scanning of the sample. The spatial dependence of the sample emission is recorded set of decay curves for subsequent sample points. With the SPC-5-versions up to 16384 decay curves can be recorded in one measurement.
Measurement of subsequent decay curves in programmed time intervals. The variation of a sample with the time is recorded as a set of subsequent decay curves.
Recording of time-resolved spectra in time windows down to 25 ps. Up to eight spectra are recorded simultaneously for the same sample in different time windows.
Optical Oscilloscope Applications. All SPC modules provide an ‘Oscilloscope Mode’ which displays subsequently measured waveforms in intervals down to some 10 ms. Thus, optimising and adjusting your measurement setup is not longer a trial-and-error procedure.
Steady state emission spectra. The high count rate of 800 MHz yields an exceptional high linearity up to extremely high peak intensities.
Steady state emission spectra with pulse excitation and gated detection. The gating reduces the detector background counts the extremely low values.
Luminescence decay curves in the us range (PMS-300). The high count rate of the PMS (800 MHz) allows to record more than 200 events for each channel in one sweep. Accumulation of several sweeps is free of dead time, therefore an extremely high repetition rate is achieved.
Time-of-flight measurements with a resolution down to 250 ns (PMS-300). The high count rate of the PMS (800 MHz) allows to record more than 200 events for each channel in one sweep. Accumulation of several sweeps is free of dead time, therefore an extremely high repetition rate is achieved.
Detection of single molecules or other particles (PMS-300). The ‘Event Mode’ of the PMS-300 allows the recording of events like the transition of a single molecule or another particle through a laser focus. The background counts are suppressed by an adjustable ‘Event Threshold’.

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