Flex02-01D Correlator Interface

A graphical user interface to the Flex02-01D hardware correlator accessing the Windows driver.

1. Introduction

The Flex02-01D by Correlator.com is an USB correlator for single- and dual-channel auto- and cross-correlation. The correlator simultaneously calculates up to four auto- and cross-correlations while recording the raw photon traces and the photon counting statistics (histograms). It is well-suited for fluorescence cross-correlation spectroscopy FCCS and similar methods.

This MATLAB interface provides an intuitive and simple access to the USB2.0 correlator hardware. It features automatic storage of the sample data, live control of the correlator hardware as well as live preview of the intensity trace, correlation curves (background corrected) and photon statistics.

2. Installation

Unpack the archive in a folder of your choice. Install the Flex02-01D driver by Correlator.com. Copy the SDK library "Flex02-01D.dll" into the private folder, start MATLAB and call "flex02.m".

3. Features

a) Live control: The graphical user interface provides live control of the correlator and previews the results during acquisition. You can set-up the correlation mode (up to four auto- and/or cross-correlations) and the integration time.

b) Auto-save: Clicking on the "File name template" button defines a folder and a file name further used as template for saving the aquired data automatically. A 3-digit file number is prepended and increased on every save. If auto-save is turned on, the raw photon traces can be saved too.

c) File formats: The aquired data is saved as a MAT-file with file name extension ".mat". Using the script allows to change the file format by modifying the private "export.m" function.

The raw photon traces are saved in a binary file with file name extension ".trace". Each byte represents the number of photons per microsecond counted in channel A or B. In case of a single auto-correlation, only channel A is stored. In all other correlation modes, both channels are stored as interleaved traces. Starting with channel A, every second byte belongs to channel A or B, respectively. Recording the raw photon traces requires a storage bandwidth of 1MByte/s per channel.

d) Background correction: The static background can be measured a priori with a blank (non-fluorescent) sample for subsequent correction of the live preview. The correlation curves approximate then the fluctuation statistics of the fluorescent signal without background. In the MAT-file, the background is saved as separate variable without altering other data.

e) Testing the interface: The graphical interface can be tested without the correlator hardware. For this purpose, use the script version and rename/remove the MEX-function "flex02d01.dll". The M-function "flex02d01.m" provides then an emulation of the hardware correlator.