STAGE Absorption imaging of unidimensional gases

In the cold atom domain, absorption imaging allows the measurement of the density distribution of diluted quantum
gases. Atoms initially trapped in a magnetic potential are released and undergo a time of flight before being
illuminated by a laser beam at resonance with an atomic transition. Finally, an optical objective allows the beam to be
imaged on a CCD camera. Comparison of the intensity distribution of the laser beam in the presence of the atoms and
that obtained in the absence of the atoms makes it possible to deduce the atomic density. The optical objective is based
on the use of two converging lenses leading to a fixed magnification and a resolution limited by the wavelength of the
laser. In principle, the addition of additional lenses reduces the size of the lens.
On our experimental device, ultracold sodium atoms are magnetically trapped on the surface of an atomchip. The
magnetic potential being very anisotropic, the gas reaches the one-dimensional regime for temperatures on the order of
hundred nanokelvin. Once released, the properties of the gas can be deduced using an absoption imaging system.
The purpose of the internship will be to design and implement such a system on the experimental device. It will start
with a simulation of the properties of the optical objective using the Zeemax software and then build it using
commercial lenses. The objective will then be experimentally characterized before being installed on the experimental
setup. Finally, it will be tested directly on the one-dimensional cold gases produced at the surface of the atomchip.