The vibration of floors can be in the order of millimeters, depending on the dynamic properties of the slab. Modern large span bats especially with shallow depth thanks to prestressed hi tensile strength bars under pedestrian steps is noticable.

The most basic way is to cast a laser beam in small tangential angle onto a tray of water from 5 cm and video the vibration of the Ray bouncing of the surface onto a surface distanced 500 cm so you get 100x magnifying power.

The vibration of floors can be in the order of millimeters, depending on the dynamic properties of the slab. Vibration of modern large span slabs especially with shallow depth thanks to prestressed hi tensile strength bars under pedestrian steps is noticable. Dynamic impact of a person's step can be many times larger than their static weight.

The most basic way is to cast a laser beam in small tangential angle onto a tray of water from 5 cm and video the vibration of the Ray bouncing of the surface of the turbulenced tray onto a surface distanced 500 cm so you get 100x magnifying power.