Mic fountain model

With the aim of spreading the knowledge on atomic clocks (field as complexe as fascinating, unrecognized by grand public and students) an atomic fountain model has been developed in the frame of FIRST-TF.

This model reproduces the way of working of a cold atoms fountain and its elements come from a real fountain. The cooling and trapping region, the microwave cavity and the detection are featured.

We have taken particularly care of the pedagogical aspect: the public can interact with the model to make the atomic fountain to work and some key-parameters may be changed to observe their effect on the atomic clock way of operation.

Some technical details on the building of this model:

  • The cold atoms cloud is simulated by a light diffusing plexiglass bowl. The launch mechanisme is made by a spring, like in a flipper. A step by step motor compresses the spring and, once the compression is over, the spring comes back to the initial position and trasnfers its moment to the bowl (see picture here below)
  • The laser cooling region is floodlit by four red laser pointers hat simulated the collimators of a real fountain. The lasers swithc off when the bowl is launched, exactly as it happens in an atomic fountain working in a pulsed regime.
  • The interaction with the microwave (in the cavity) is underlined by the introduction of a LED that shines the cavity itself and the bowl when it crosses the cavity. By the help of a touch-screen the public can choose the microwave characteristics
  • The detection is simulated by a green laser pointer that, from the top, irradiates the bowland makes it well visible. An extra laser pointer, whose light beam is overlapped to the first one, allows one to create a relation between the microwave characteristics and the color of “the atoms”.


The driving electronics is fully digital (Arduino Uno board, whose software is an open source available on the web). It is thus possible to make the atomic clock model operating in automatized mode, if whished. The electronics board and the mechanics for launching the bowl are fixed on the model base (see picture), so they are unlikely not visible. A board of optically isolatedrelays, driven by Arduino Uno, protect the laser pointers from uncontrolled dangerous transitoires.

This atomic fountain model, prepared by the SYRTE, will be shared with the institutes of the FIRST-TF network and we forsee to present it in public events as Fête de la Science, Nuit des Chercheurs, Journées Portes Ouvertes, etc… as well as in secondary and high schools for demo lectures.

Contact : contact(at)first-tf.com