Nanosecond compressive fluorescence lifetime microscopy imaging via the RATS method with a direct reconstruction of lifetime maps

TL;DR

This paper advances fluorescence lifetime imaging microscopy by introducing nanosecond resolution using the RATS method with digital laser modulation and a single-pixel camera approach, enabling faster and more stable PL dynamics mapping.

Contribution

It presents a novel nanosecond-resolution RATS-based FLIM technique with a single-pixel camera, improving speed and stability over traditional methods.

Findings

Achieved nanosecond temporal resolution in PL dynamics measurement.

Developed a single-pixel camera approach for faster FLIM evaluation.

Validated the method with experimental mapping of a crystal surface.

Abstract

RAndom Temporal Signals (RATS) method has proven to be a useful and versatile method for measuring photoluminescence (PL) dynamics and fluorescence lifetime imaging (FLIM). Here, we present two fundamental development steps in the method. First, we demonstrate that by using random digital laser modulation in RATS, it is possible to implement the measurement of PL dynamics with temporal resolution in units of nanoseconds. Secondly, we propose an alternative approach to evaluating the FLIM measurements based on a single-pixel camera experiment. In contrast to the standard evaluation, which requires a lengthy iterative reconstruction of PL maps for each timepoint, here we use a limited set of predetermined PL lifetimes and calculate the amplitude maps corresponding to each lifetime. The alternative approach significantly saves post-processing time and, in addition, in a system with noise present, it shows better stability in terms of the accuracy of the FLIM spectrogram. Besides simulations that confirmed the functionality of the extension, we implemented the new advancements into a microscope optical setup for mapping PL dynamics on the micrometer scale. The presented principles were also verified experimentally by mapping a LuAG:Ce crystal surface.