Method and apparatus for high density storage of analog data in a durable medium

Abstract

Analog data such as text and images are stored in microscopic analog format on a disk surface capable of maintaining the information for 1000 years or more whereby simple optical magnification will result in one being able to read the information formed therein. For a disk read by backlighting, as with microfiche, a photosensitive material is overlayed on hard metal surface which in turn is formed on a transparent glass or quartz material. A laser beam is focused on certain desired portions of the photosensitive material and the exposed material and underlying hard metal layer etched off to form pits down to the transparent layer corresponding to the analog information. The resulting disk can then be used to produce archival copies and distribution copies using hot embossing or other disclosed techniques.

1 . A method for forming a negative copy of analog data expressed as three dimensional surface features formed on substrate, the method comprising the steps of:
 forcing a surface of the substrate containing the three dimensional surface features in contact with a temperature sensitive polymer under low vacuum and at a temperature higher than the glass transition temperature of the polymer to thereby transfer a negative of the three dimensional surface features onto the polymer, said surface and polymer selected to have to different thermal expansion rates;   allowing the polymer to solidify and shrink during a cooling process to effect a release of the polymer from the substrate surface; and   coating a high contrast material over the polymer surface containing the negative of the three dimensional surface features.   
     
     
         2 . The method of  claim 1 , wherein the high contrast material is selected from the group consisting of Ti, Ni, Cr or other metal. 
     
     
         3 . The method of  claim 1 , further including the step of forming a scratch resistant layer over the high contrast material. 
     
     
         4 . The method of  claim 3 , wherein the scratch resistant layer is selected from the group consisting of diamond-like-carbon (DLC), aluminum oxide, or silicon dioxide. 
     
     
         5 . A method for creating analog data in three dimensions in the surface of a substrate comprising the steps of:
 exposing portions of an energy sensitive glass substrate to directed energy only at predefined pixel locations corresponding to a reduced image of the analog data to form a gray level mask pattern;   transmitting the gray level mask pattern to a photoresist layer formed over a substrate; and   removing portions of the photoresist layer corresponding to the gray level mask pattern to form a three dimensional representation of the optical data within the photoresist layer.   
     
     
         6 . The method of  claim 5 , further including the step of depositing a thin conductive layer over the unremoved portions of the photoresist layer. 
     
     
         7 . The method of  claim 6 , further including the steps of:
 electrodepositing an archival quality metal over the conductive layer; and   separating the conductive layer and electrodeposited layer from the photoresist layer and substrate.   
     
     
         8 . A method for forming a copy of analog data expressed as three dimensional surface features formed on substrate, the method comprising the steps of:
 depositing a thin conductive layer over the three dimensional surface features of the substrate;   electrodepositing an archival quality metal over the conductive layer; and   separating the conductive layer and electrodeposited layer from the substrate.   
     
     
         9 . The method of  claim 8 , wherein the step of separating the conductive layer and electrodeposited layer from the substrate, where the electrodeposited layer has a different thermal rate of expansion from the substrate, includes heating the resulting structure. 
     
     
         10 . The method of  claim 8 , wherein the step of separating the conductive layer and electrodeposited layer from the substrate, where the substrate is a polymer, includes dissolving the polymer with a ketone.