FIELD: physics.
SUBSTANCE: one version of the invention provides a diffraction ophthalmic lens which can be, for example, an intraocular lens which includes an optical element having a front surface and a rear surface, where the optical element provides a long focus. The broken diffraction structure containing a collection of diffraction zones lies on at least one of said surfaces to provide near focus. Each zone is separated from the neighbouring zone by the boundary of a zone which causes optical delay in the incident light. Also, at least two successive boundaries of the zone have such a configuration where the difference between their corresponding phase delays for at least one wavelength of incident light is greater than approximately ¼ of the wavelength for directing part of the incident light to the position between the near and far foci.
EFFECT: high quality of the intermediate image without deterioration of near and far vision.
36 cl, 8 dwg
