Thermal imaging of nanostructures by quantitative optical phase analysis.
We introduce an optical microscopy technique aimed at characterizing the heat generation arising from nanostructures, in a comprehensive and quantitative manner. Namely, the technique permits (i) mapping the temperature distribution around the source of heat, (ii) mapping the heat power density delivered by the source, and (iii) retrieving the absolute absorption cross section of light-absorbing structures. The technique is based on the measure of the thermal-induced refractive index variation of the medium surrounding the source of heat. The measurement is achieved using an association of a regular CCD camera along with a modified Hartmann diffraction grating. Such a simple association makes this technique straightforward to implement on any conventional microscope with its native broadband illumination conditions. We illustrate this technique on gold nanoparticles illuminated at their plasmonic resonance. The spatial resolution of this technique is diffraction limited, and temperature variations weaker than 1 K can be detected.
Institut Fresnel, UMR CNRS 7249, Domaine Universitaire Saint-Jérôme, 13397 Marseille, France. guillaume.baffou@Fresnel.fr
Guillaume
G
Baffou
Pierre
P
Bon
Julien
J
Savatier
Julien
J
Polleux
Min
M
Zhu
Marine
M
Merlin
Hervé
H
Rigneault
Serge
S
Monneret
D006046:Gold / Q000737:chemistry; D006358:Hot Temperature; D008853:Microscopy / Q000379:methods*; D049329:Nanostructures / Q000737:chemistry*; D055620:Optical Phenomena
D006046:Gold