Figure 4. Layout of the optical setup (not to scale).

A microsphere lies on a sample and viewed under a microscope. It is attached to the micropipette using air suction or optical glue. The micropipette with the microsphere is attached to the micromanipulator via a V-grove holder. Driving the micromanipulator allows movement of the sphere in three dimensions. Inset shows the microscope image of the microsphere attached to the pipette by an optical glue. Image in air under 40× objective lens, the scale bar is 10 μm.