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micro optical deviceINTRODUCTION

We recently demonstrated a new design and concept for tunable microlenses and wavefront shaping [Berto et al, Nature Photonics, 13, p649–656, 2019]. Our approach, coined as Smartlens, uses microscale, thermally-induced modifications of the optical phase: a micro-resistor locally changes the temperature distribution in a polymer, which induces local changes of the refractive index as shown in fig. 1 a-c (this temperature dependence of the index is well known to induce mirages, or fata morgana). With a resistor of well-designed shape, the electrically controlled heating can modify and shape the wavefront. Importantly, they can be arranged in matrices to obtain arrays of electrically-driven lenses, and we have shown that several planes inside a 3D sample can thus be projected to form a single camera image of planes located at various, chosen depths. These systems hold a strong applicative potential as they are compact, relatively achromatic, polarization-insensitive, and can be mass-fabricated.

Far from being limited to simple lenses, they can also create more complex shapes, called freeform. To this aim, resistor wires are designed to provide complex shapes to e.g. correct optical aberrations, as shown in fig.1d. However, the devices we have designed so far are limited to a single shape and function: if they correct e.g. astigmatism, they do not address any other aberrations (spherical, etc.).

In this PhD project, we propose to create and apply reconfigurable lenses or aberration correctors, which will allow the system to dynamically adapt to a chosen set of corrections. A single Smartlens will correct astigmatism, spherical, or other freeform deformations, as chosen by the user. This will provide entirely novel, agile and electrically-edriven freeform lenses with a potential to deeply impact the field of photonics (e.g. adaptive optics) and consumer products (cell phones, 3D displays…).

This project will be carried out within the photonics department of the Institut de la Vision, in close collaboration with ETH Zürich, where Smartlens fabrication will be carried out.

In the context of the high-level neuroscience studies carried out at Institut de la Vision, one of the priorities will be the development of a refocusable endoscope with embedded aberration/image corrections to image deep inside living tissues.

PhD funding currently available (ANR funding)
Profile: Taste and experience in instrumental optics. Skills in optical modelling/microfabrication/biology are appreciated but not mandatory.
Location: Institut de la vision, 75012, Paris (Métro Bastille).
Contacts:
pascal.berto@parisdescartes.fr
gilles.tessier@sorbonne-universite.fr

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