#Y2024 #光学器件 In optics, a Fabry–Pérot interferometer (FPI) or etalon is an optical cavity made from two parallel reflecting surfaces (i.e.: thin mirrors). Optical waves can pass through the optical cavity only when they are in resonance with it. It is named after Charles Fabry and Alfred Perot, who developed the instrument in 1899. Etalon is from the French étalon, meaning "measuring gauge" or "standard".  [https://lightmachinery.com/optics/custom-optics/etalons/](https://lightmachinery.com/optics/custom-optics/etalons/) [https://lightmachinery.com/optical-design-center/etalon-designer/](https://lightmachinery.com/optical-design-center/etalon-designer/)