Pile-up free fluorescence lifetime imaging with a SPAD-based single pixel camera

Area of Science:

• Optics and Photonics
• Biomedical Imaging
• Materials Science

Background:

• Single-pixel imaging (SPI) is widely used in fluorescence lifetime imaging (FLIM).
• Time-correlated single photon counting (TCSPC) offers high temporal resolution but suffers from pile-up, limiting photon count rates to 1-5% of the laser excitation rate.
• This limitation hinders real-time monitoring of biological phenomena.

Purpose of the Study:

• To introduce a hardware-based method to eliminate pile-up in single-pixel camera (SPC) based FLIM.
• To enable high-fidelity lifetime map acquisition at significantly increased count rates.
• To facilitate real-time monitoring of biological processes using advanced imaging techniques.

Main Methods:

• A novel hardware-based method was applied to a single-pixel camera (SPC).
• The dead time of the single-photon avalanche diode (SPAD) detector was matched to an integer multiple of the laser period.
• This approach completely avoids the pile-up phenomenon.

Main Results:

• Undistorted and high-fidelity lifetime maps were acquired at count rates up to 40%.
• This count rate is significantly higher than the limit imposed by the classic pile-up phenomenon.
• The method remains effective even with computational imaging algorithms.

Conclusions:

• The developed hardware method effectively overcomes the pile-up limitation in SPI-FLIM.
• This breakthrough allows for significantly faster data acquisition and real-time biological monitoring.
• High-fidelity fluorescence lifetime imaging is achievable at unprecedented count rates.