RADIATION OPTICAL ELEMENT

摘要

It was found that poly-(phenyleneoxadiazole) is heat treated at a high temperature above 2800.degree.C under normal pressure thereby to be easily formed into a crystalline graphite. A graphite film obtained by graphitizing a film-like poly-(phenyleneoxadiazole) has a sufficient flexibility while being monocrystalline. The thus obtained graphite film is able to have a sufficient area, which is plastered on a base plate thereby to be used as a reflecting mirror and a lens for radiation such as X-ray, neutron ray, etc.