A highly secure optical key access control system utilizing unique optical refraction properties of non-duplicatable transparent objects to secure premises or computer databases is disclosed. The said access control system includes an optical key containing an optical element with unique refraction properties and an access module comprising a light source, an image catching array and an electronic processor. The optical element of the optical key is inserted into the access module between the light source and the image catching array at the initial and then several following prearranged positions and a resulting set of unique refraction images appearing on the surface of the image catching array is processed with the electronic processor for comparison against preauthorized sets of refraction images to grant or deny access to the protected premises or protected computer databases.