Casimir force tips the balance
This experiment measures the Casimir force between a metallized plate and a metallized sphere fixed to the tip of the cantilever of an atomic force microscope.
When the sphere is brought near to the plate, an attractive Casimir force causes the cantilever to bend. This bending is monitored by bouncing a laser off the top of the cantilever and using photodiodes to record the reflected light.
The electron micrograph shows a metallized sphere attached to the triangular cantilever tip of an atomic force microscope. (Picture credit: Umar Mohideen, University of California at Riverside)