Abstract: A method and apparatus for recording and reading information in a recording medium comprising a thin film of an organic compound having polymorphisms. The free energy of each polymorphism is different with each other. Information is recorded in the recording medium by applying energy to the recording medium and transferring locally the polymorphism of the organic compound to another polymorphism of the organic compound. The amount of the energy corresponds to the difference in free energy between the polymorphisms. Information is read from the recording medium by optically discriminating between the optical absorption properties of the polymorphisms.

Abstract: A cation exchange polyimide resin having resistance to organic solvents which contains polyamidocarboxylic acid units providing sites of ion exchange and represented by the formula (I): ##STR1## wherein R.sup.1 is a tetravalent organic group, and R.sup.2 is a bivalent organic group, which is capable of trapping cations from organic solvents.

Abstract: A process for preparing an organic compound thin film for use in an optical device including steps of forming a multiplicity of geometric linear streaks with microscopic unevenness in section on a substrate at least whose surface is made up of an amorphous organic polymer layer; thereafter vapor-depositing on the surface an organic compound capable of exhibiting non-linear optical characteristics to form a non-linear optical material film.

Abstract: A method of manufacturing a polyimide thin film is disclosed which comprises supplying vapors of a polyimide starting material comprising a plurality of polyimide forming monomers into a plasma atmosphere, transferring the ionized polyimide starting material, under an electric field, to the surface of a glass or metallic substrate and depositing the material thereon, and heating the same during or after deposition, thereby forming a polyimide thin film as an orientation film on the substrate.