Description

You are looking at a microscopic mirror used in quantum optics experiments. It is made of alternating layers of SiO2 and Ta2O5, and it is about 6 microns tall, roughly the size of a human red blood cell. The triangles are holes that serve as windows which we use to correctly position our lasers.

During the fabrication process of these devices, we rinse them in water and alcohol, which sometimes leave small residues or stains after they evaporate. The imaging technique used to obtain this picture is called dark-field microscopy. This technique is what makes the clean and smooth areas look dark, and the sharp features such as streaks and tiny spots look bright, like stars in outer space.