Patent ID: 7357969

Claim:
A phase-change optical recording medium, comprising: a first information layer arranged in a position close to a light incident side and including a lower dielectric film, a phase-change optical recording film, an upper dielectric film, a semitransparent reflective film and a protective film viewed from the light incident side; a second information layer arranged in a position remote from the light incident side and including another lower dielectric film, another phase-change optical recording film, another upper dielectric film and a total reflective film viewed form the light incident side; and an interlayer separating film arranged between the first information layer and the second information layer, wherein at least one of the first information layer and the second information layer comprises a noise reduction film, the noise reduction film in the first information layer being arranged between the protective film and the interlayer separating film and in contact with the interlayer separating film, the noise reduction film in the second information layer being arranged between the another lower dielectric film and the interlayer separating film and in contact with the interlayer separating film, and the noise reduction film comprising at least one material selected from the group consisting of SiO x (1≦x≦2), SiOC, MgO x (1≦x≦2), Al 2 O 3 , Si—Al—O (mullite), Yb 2 O 3 , Si 3 N 4 , BaF 2 , BiF 3 , CeF 3 , LaF 3 , NdF 3 , PbF 2 , DyF 2 , GdF 3 , HoF 3 , NdF 3 , SrF 2 , ThF 4 , YbF 3 , YF 3 , AlF 3 , CaF 2 , MgF 2 , NaF, Na 3 AlF 6 , Na 5 Al 3 F 14 , LiF, ThO 2 , La 2 O 3 , Gd 2 O 3 , Bi 2 O 3 , HfO 2 , Nd 2 O 3 , Sb 2 O 3 , Sc 2 O 3 , V 2 O 5 , Y 2 O 3 , AlN, CeO 2 , Ho 2 O 3 , In 2 O 3 , SnO 2 , Pr 6 O 11 and ZnO, and wherein if the first information layer comprises the noise reduction film, the protective film is formed of ZnS:SiO 2 , and if the second information layer comprises the noise reduction film, the another lower dielectric film is formed of ZnS:SiO 2 .