Micro to macro scale simulation coupling for stray light analysis.

Stray light in an optical system is unwanted parasitic light that may degrade performance. It can originate from different sources and may lead to different problems in the optical system such as fogging, ghost images for imagers, or inaccurate measurements for time of flight applications. One of the root causes is the reflectivity of the sensor itself.

Observing the onset of effective mass.

The response of a particle in a periodic potential to an applied force is commonly described by an effective mass, which accounts for the detailed interaction between the particle and the surrounding potential. Using a Bose-Einstein condensate of (87)Rb atoms initially in the ground band of an optical lattice, we experimentally show that the initial response of a particle to an applied force is in fact characterized by the bare mass. Subsequently, the particle response undergoes rapid oscillations and only over time scales that are long compared to those of the interband dynamics is the effective mass observed to be an appropriate description.