OPTICAL ELEMENT, OPTICAL COMPOSITE ELEMENT, AND OPTICAL COMPOSITE ELEMENT HAVING PROTECTIVE FILM

An optical element having, on one surface thereof, multiple recessed sections arranged at a most frequent pitch equal to or less than the wavelength of light in the operating environment, the optical element having, when seen in plan view, multiple domains in which the multiple recessed sections are aligned in a predetermined arrangement, and, multiple protruding sections formed in a region sandwiched between the multiple domains and/or in a region surrounded by the multiple recessed sections inside the domains, the multiple protruding sections accounting for a surface area ratio of 1%-15% as seen in plan view.