Patent ID: 6160787
Filing Date: 2000-12-12
Classification: G11B

Abstract:
A multi data storage medium for data optically recorded in pit and land structures having data, a portion of which is readable by light of a first frequency, and not by light of a second frequency, and a portion of which data is readable by light of a second frequency and not the first frequency, comprisinga first data surface formed as a series of pits and lands in a first plastic layer,a thin film of material forming a layer having upper and lower surfaces, said lower surface in contact with the pits and lands of said first data surface, wherein said film passes light of the second frequency and reflects light of the first frequency,an adhesive layer in contact with the upper surface of said thin film, said adhesive layer being transparent to light of the second frequency,a second plastic layer in contact with said adhesive, said second plastic layer having a second data surface comprising a series of pits and lands remote from said adhesive,a reflective layer for said second frequency of light in contact with the second data surface,wherein said thin film comprises a semiconducting material having a large index of refraction for reflectivity with a band gap energy of approximately 1.7 eV.