Improving the counting efficiency in time-correlated single photon counting experiments by dead-time optimization.

Area of Science:

• Photonics and Spectroscopy
• Advanced Instrumentation
• Fluorescence Lifetime Imaging

Background:

• Time-Correlated Single Photon Counting (TCSPC) is a sensitive fluorescence lifetime measurement technique.
• TCSPC's main limitation is long data acquisition times due to pile-up and counting losses at high excitation rates.
• Existing multi-module TCSPC systems increase counting capability but also cost and complexity.

Purpose of the Study:

• To propose an alternative approach to multi-module TCSPC systems.
• To develop a new detector and processing electronics to reduce system dead time.
• To enable efficient photon collection and faster fluorescence lifetime measurements at high excitation rates.

Main Methods:

• Development of a fast active quenching circuit for single-photon avalanche diodes with a 12.4 ns minimum dead time.
• Introduction of a novel Fast Time-to-Amplitude Converter (F-TAC) using integrated TACs and a sequential router.
• Design focused on minimizing overall system dead time for high photon collection efficiency.

Main Results:

• The developed fast active quenching circuit achieves a minimum dead time of 12.4 ns.
• The F-TAC enables operation near the detector's maximum count rate (∼80 Mcps).
• Reduced pile-up losses were observed, addressing a key historical criticism of TCSPC.

Conclusions:

• The proposed system offers an efficient alternative to multi-module TCSPC for high-rate measurements.
• The new detector and F-TAC significantly improve photon collection efficiency.
• This advancement allows for faster and more robust fluorescence lifetime measurements.