An optical interferometer is an interferometer for visible light, and/or nearby portions of the neighboring bands, infrared and ultraviolet. Use of them is called optical interferometry.
Some research-telescope optical instruments incorporate interferometry internally, e.g., a Michelson interferometer in an imaging Fourier transform spectrometer. Also, interferometry using a grating rather than a prism qualifies. Gravitational-wave detectors such as LIGO also incorporate them.
Optical interferometers analogous to radio and microwave interferometers and arrays, e.g., aperture synthesis, for measurements and images with a very fine angular resolution have been created. There are challenges in designing, building, and operating them, otherwise they would be in more common use. Examples: