3D Microscopy

Presentation

Digital Heterodyne holography is a major part of the activities of the team, underlying much –but not all- of our scientific production. Applied to nanoparticle detection, these 3D techniques allow the use of super localization: although optical microscopes are limited by diffraction to spatial resolutions of the order of the micrometer, we have shown that the position of individual objects can actually be determined with much better accuracy, of the order of a few nanometers only. We have developed several microscopes able to track in real time the random (Brownian) motion of such particles in 3D. We have shown that this tracking can be used to characterize the particle itself (size, chemical behavior, etc…), or its local environment (chemical composition, optical properties, etc…).

More recently, a system has been developed to use this localization information to drive an adaptive optical system which redirects the light scattered by a moving particle towards a spectrometer, allowing long spectral acquisitions even on small, weakly scattering objects. All these aspects are backed by optical and thermal modeling and completed with numerical simulations.

In addition, several members of the team have a strong background in photothermal sciences: systems developed in the team for high resolution temperature imaging or thermal properties measurements are now routinely used in the lab. A thermal endoscope has recently been developed to measure local temperatures in-vivo.