StrobeLock: Time-Correlated Single Photon Counting
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StrobeLock is an extension for the WITec alpha300 microscope series, which enables time-correlated single photon counting (TCSPC) measurements. TCSPC records the time-resolved luminescence or fluorescence decay after pulsed stimulation. In Time-resolved Luminescence Microscopy (TLM), the intensity decay is recorded at each image pixel. Various parameters describing each decay can be determined, such as single- or even multi-exponential relaxation times. Images can then be color-coded according to any of the extracted parameters, revealing local differences in the emission behavior of a sample. For example, extracting the lifetime of fluorophores allows for Fluorescence Lifetime Imaging (FLIM). Combining the time-resolved data with Raman, AFM or SNOM images yields additional information on the investigated materials.
StrobeLock benefits:
- Precise time-resolved measurement of fluorescence and other luminescence decays
- Sample excitation via a pulsed laser for fluorescence or via a pulse generator for electrically stimulated luminescence
- Adjustable excitation pulse frequencies (up to 100 MHz)
- Instrument response function typically below 120 ps
- Full integration with WITec Control and WITec Project software
- User-friendly combination options with Raman, AFM and SNOM
Time-resolved Luminescence microscopy (TLM)
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With Time-resolved Luminescence Microscopy (TLM), the luminescence properties of light-emitting devices, such as LEDs, can be investigated and spatial differences can be revealed. Light emission is stimulated by an electrical pulse generator and its intensity is recorded in a time-resolved manner. Thus, relaxation times or response times can be calculated for each image pixel and visualized. TLM can be used for example for the quality control of LEDs.
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Time-resolved Luminescence Microscopy (TLM) on a blue light-emitting diode (LED).
Left: Map of local relaxation times; scale bar 7 µm.
Right: Contour plot of the temporal start of the luminescence emission; scale bar 10 µm.
Fluorescence Lifetime Imaging (FLIM)
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Fluorescence Lifetime Imaging Microscopy (FLIM) determines the average fluorescence lifetime for each image pixel from the time-resolved fluorescence decay after excitation by a pulsed laser. The resulting FLIM image is color-coded according to the lifetime, displaying its spatial distribution in a sample. In combination with other imaging techniques, such as Raman imaging or AFM, FLIM extends the amount of information gained from one sample.
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Fluorescence Lifetime Imaging (FLIM) of N,N′‐bis(1‐ethylpropyl)‐3,4,9,10‐perylenebis(dicarboximide) (EPPTC) crystal needles. Left: Total fluorescence intensity; scale bar 5 µm. Right: FLIM; scale bar 5 µm.
Images are a courtesy of Xinping Zhang, Institute of Information Photonics Technology and College of Applied Sciences, Beijing University of Technology.