A method for producing a library includes the steps of calculating a
plurality of conditions for a reflection light from a periodic pattern by
changing the sectional shape of the periodic pattern, a condition of an
incident light which is emitted to the periodic pattern, an optical
constant of a material which forms the periodic pattern, relating a
plurality of the libraries to the plurality of the reflection light's
conditions, and the optical constant corresponding to the plurality of
the reflection light's conditions respectively.