Optical information recording medium
Optical information recording medium having protective layer
Optical recording and reproducing disc
Optical recording disk
Protected optical disc comprising a flexible closure element
Protective construction for optical disk units
Radial access drive for an optical disk recorder
Radiation-sensitive record disc
Radiation-sensitive record disc with improved internal structure
Radiation-sensitive record utilizing an annular ring and project
Recording device with flexible chart
Recording medium of air-sandwich structure
Recording medium of deformable air-sandwich structure