{ "items" : [
    { "id" : "http://dbpedia.org/resource/Crystal_optics"
      "properties" : {
        "http://www.w3.org/2000/01/rdf-schema#comment" : [ "Crystal optics is the branch of optics that describes the behaviour of light in anisotropic media, that is, media (such as crystals) in which light behaves differently depending on which direction the light is propagating. The index of refraction depends on both composition and crystal structure and can be calculated using the Gladstone–Dale relation."] } } }
