Super-resolution high-speed optical microscopy for fully automated readout of metallic nanoparticles and nanostructures

Abstract

We have designed a fully automated optical microscope running at high-speed and achieving a very high spatial resolution. In order to overcome the resolution limit of optical microscopes, it exploits the localized surface plasmon resonance phenomenon. The customized setup using a polarization analyzer, based on liquid crystals, produces no vibrations and it is capable of probing isolated nanoparticles. We tested its performance with an automated readout using a fine-grained nuclear emulsion sample exposed to 60 keV carbon ion beam and, for the first time, successfully reconstructed the directional information from ultra-short tracks produced by such low-energetic ions using a solid-state tracking detector.

Deep Learning for direct Dark Matter search with nuclear emulsions

“…The emulsion readout is performed with a custom-designed super-resolution optical microscope [9,4]. This allows fast processing (e.g.…”

“…The plasmon resonance effect comes from the interaction of linearly polarised light with small metallic objects [9,4]. The intensity of reflected light depends on the polarisation angle of the illuminating light if the object has a non-spherical shape.…”

“…The barycenter shift produced by the variation of the polarisation angle can be used to try to distinguish single grains and tracks composed of more than one grain. Here we follow the approach similar to the one described in [4,5].…”

“…In this article, we present the Deep Learning (DL) approach to analysing the experimental data in the nuclear emulsionbased directional detection experiment and compare it with a more conventional cut-based approaches adopted by the NEWSdm (Nuclear Emulsion for WIMP Search with direc-tional measurement) experiment [3]: we repeat the analysis of the brightness peak evolution due to the change of the light polarisation in the optical microscope similar to [4,5] and use the results of the elliptical shape analysis for optical images in unpolarised light from [6].…”

Directional dark matter search with nuclear emulsions

“…The analysis of this displacement allows to distinguish clusters made of a single grain from those made of two or more grains. To carry out such an analysis in a completely automated way, the collaboration has designed and built a dedicated super-resolution microscope [12], shown in the left panel of Fig.1, which is equipped with a polarization spectrum analyser based on liquid crystals. An unprecedented accuracy about 3 nm has been achieved in both coordinates with this…”