Paul D. Kunz, Steven R. Jefferts, Thomas P. Heavner
We are developing a transportable laser-cooled rubidium (Rb) atomic fountain frequency standard. Over the last year we have built the Ramsey cavity and rubidium source oven and are preparing to assemble the physics package. We have also made numerous refinements to the laser package including transitioning to a new style of laser diode, vastly improving the optical phase-locked loops (OPLL), and improving the optical spatial mode to get more power out of the optical fibers. These refinements have enabled the laser cooling to collect many more atoms which will improve the fountains signal-to-noise ratio.