(computing) The electronic identification and digital encoding of printed or handwritten characters by means of an optical scanner and specialized software.

(physics) a property caused by asymmetrical molecular or crystal structure that enables a compound or crystal to rotate the plane of incident polarized light

(chemistry) Any one of a number of compounds that exhibit optical isomerism.

(American spelling) Alternative form of optical fibre

(British spelling) A thin, transparent, flexible fibre, made of glass or plastic, used for transmitting light.

The colours of the rainbow. / (physics) The distribution of colours produced when white light passes through a prism. / (astronomy, physics) The range of frequencies of visible light.

(chemistry, physics) the variation in the optical rotation of a substance with the wavelength of light

(optics) A disk of high-quality quartz glass having at least one side ground and polished with a deviation in flatness less than 50 nanometers all over, and a surface quality of 5 microfinish or less; used, in an interferometer, to measure the flatness of other surfaces.

regarding or using optics

(astronomy) A star that appears as a double due to an optical illusion; in reality, the stars may be far apart from each other.