Stochastic focusing from 3D to 2D reveals ultra-weak luminescence

Abstract

Measuring ultra-low luminescence is a considerable challenge, despite the current availability of highly sensitive photon detectors that combine very low noise and high quantum efficiency. One reason is that ultra-weak luminescence is typically produced by extended samples, in which the photon sources not only have a very low emission rate but also exhibit very low spatial density. Furthermore, in the case of liquid sample, molecular photon sources move in 3D. Hence the main question. What is the most effective way to collect the rare photons produced isotropically by an extended 3D sample and bring them to the smallest possible 2D detection surface? In my presentation, I describe a design that combines (a) a very high-efficiency integrating sphere, (b) an EMCCD with optimised detectivity, and (c) the optimal collection geometry that performs a 3D/2D stochastic conjugation between the volume inside the sphere and the detector surface. We have demonstrated that this device can detect ultra-weak light, with a detection limit of ~110 photons per litre per second. Thanks to this unprecedented sensitivity, we were able to detect the luminescence produced by the non-catalytic disproportionation of hydrogen peroxide in pure water, which had never been observed before. We were also able to detect the ultra-weak bioluminescence produced by yeast cells at the beginning of their growth. Our work opens up new perspectives for the study of ultra-weak luminescence, and the concept of 3D/2D stochastic conjugation should enable the design of new light detection methods for large samples or diluted emitters.

Speaker

Francois Amblard
Ulsan National Institute of Science and Technology
South Korea

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