Bump-forming media including thin intermediate reflective layer and methods for writing, reading, and erasing same

An optical recording medium including a triple layer recording structure, comprising:

• (a) a first layer of a first material;
• (b) a second layer of a second material;
• (c) a third layer of a third material interposed between said first and second layers;
• (d) said first, second and third layers cooperating as a medium for forming therein an optically detectable deformation by thermal expansion of said first material deforming said second and third layers without liquefaction or gasification of said first, second, or third materials when said first material is locally heated with light radiation of a first preselected wavelength L.sub.1 ;
• (e) said first, second, and third materials being sufficiently bonded together so as to enable said second layer, through said third layer bonded thereto, to hold said first material in expanded configuration upon cessation of said L.sub.1 and cooling of said first material, retaining said optically detectable deformation, said second layer being sufficiently strong and rigid to hold said first material in expanded condition, said third layer including reflective means for enhancing the optical reflectance of said optically detectable deformation;
• (f) said first, second and third layers further cooperating as an erasable optical recording medium for relaxing said optically detectable deformation without liquefaction or gasification of said first, second, or third materials when said second material is locally heated with light of a second preselected wavelength L.sub.2, said third layer being sufficiently bonded to said first and second layers to enable said first layer, through said third layer bonded thereto, to pull said second layer flat;
• and
• (g) said second layer adapted to substantially transmit said L.sub.1 and substantially absorb said L.sub.2 and said third layer adapted to partially transmit and partially reflect L.sub.1.