Dual-wavelength parallel interferometer with superhigh resolution

A dual-wavelength parallel interferometer for subnanometer displacement measurement is introduced. A synthetic wavelength is used to subdivide the fringes formed by a single wavelength. An experimental setup that uses a heat-stabilizing dual-wavelength 633-nm He-Ne laser as the light source is established. The primary experimental result shows that a resolution of 0.210 nm over a 350-nm range has been achieved.