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Proceedings Paper

Phasor-based widefield FLIM using a gated 512×512 single-photon SPAD imager
Author(s): Arin Can Ulku; Claudio Bruschini; Ivan Michel Antolovic; Shimon Weiss; Xavier Michalet; Edoardo Charbon
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Paper Abstract

Single-photon avalanche diode (SPAD) imagers can perform fast time-resolved imaging in a compact form factor, by exploiting the processing capability and speed of integrated CMOS electronics. Developments in SPAD imagers have recently made them compatible with widefield microscopy, thanks to array formats approaching one megapixel and sensitivity and noise levels approaching those of established technologies. In this paper, phasor-based FLIM is demonstrated with a gated binary 512×512 SPAD imager, which can operate with a gate length as short as 5.75 ns, a minimum gate step of 17.9 ps, and up to 98 kfps readout rate (1-bit frames). Lifetimes of ATTO 550 and Rhodamine 6G (R6G) solutions were measured across a 472×256 sub-array using phasor analysis, acquiring data by shifting a 13.1 ns gate window across the 50 ns laser period. The measurement accuracy obtained when employing such a scheme based on long, overlapping gates was validated by comparison with TCSPC measurements and fitting analysis results based on a standard Levenberg-Marquardt algorithm (<90% accuracy for the lifetime of R6G and ATTO 550). This demonstrates the ability of the proposed method to measure short lifetimes without minimum gate length requirements. The FLIM frame rate of the overall system can be increased up to a few fps for phasor-based widefield FLIM (moving closer to real-time operation) by FPGA-based parallel computation with continuous acquisition at the full speed of 98 kfps.

Paper Details

Date Published: 22 February 2019
PDF: 8 pages
Proc. SPIE 10882, Multiphoton Microscopy in the Biomedical Sciences XIX, 108820M (22 February 2019); doi: 10.1117/12.2511148
Show Author Affiliations
Arin Can Ulku, Ecole Polytechnique Fédérale de Lausanne (Switzerland)
Claudio Bruschini, Ecole Polytechnique Fédérale de Lausanne (Switzerland)
Ivan Michel Antolovic, Ecole Polytechnique Fédérale de Lausanne (Switzerland)
Shimon Weiss, Univ. of California, Los Angeles (United States)
Xavier Michalet, Univ. of California, Los Angeles (United States)
Edoardo Charbon, Ecole Polytechnique Fédérale de Lausanne (Switzerland)

Published in SPIE Proceedings Vol. 10882:
Multiphoton Microscopy in the Biomedical Sciences XIX
Ammasi Periasamy; Peter T. C. So; Karsten König, Editor(s)

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