Time-Correlated Single Photon Counting (TCSPC) with multiple detector channels is invaluable in many fluorescence sensing applications. However, existing instrumentation is often limited in its number of independent input channels. Solutions based on multiplexing ("routing") provide input channels that are not truly independent, causing artifacts in correlation measurements and limiting applications with high count rates. On the other hand, parallel operation of complete TCSPC units, each with their own host computer interface, will result in multiple data streams arriving at the host computer. This causes complications in real-time analysis of time-tagged photon data where the order and temporal relation of events across all channels is critical. Here we present a new modular architecture allowing scalability in terms of the number of input channels (currently 8 but potentially 64), while using one common synchronization channel, delivering a single output data stream that contains time-tag records for all events from all inputs in correct temporal order, despite any variations in event rates across the channels. We discuss the influence of pile-up, resulting limitations and solutions based on parallelization. This is especially important when measuring strong cellular samples or autofluorescent species. Selected application results will be shown.

Date Published: 25 February 2009
PDF: 9 pages
Proc. SPIE 7183, Multiphoton Microscopy in the Biomedical Sciences IX, 71830C (25 February 2009); doi: 10.1117/12.808716

Published in SPIE Proceedings Vol. 7183:
Multiphoton Microscopy in the Biomedical Sciences IX
Ammasi Periasamy; Peter T. C. So, Editor(s)