Amorphous materials can be used in a variety of configurations for optical recording and storing of information. Focused laser beams yield changes in state between crystalline and amorphous giving high quality images without ablation or post processing of the film. Tailoring material compositions to a particular application results in films that can be read in reflection or transmission, and store information in a read-only or erasable form. The materials inherently provide permanence of storage, even in the case of erasable films, due to threshold imaging mechanisms. Films can be coated on a variety of substrates, including flexible plastic, sheet plastic, and glass, depending on reading and writing system requirements.
David Strand, David Strand,
"Optical Recording With Amorphous Materials", Proc. SPIE 0222, Laser Scanning and Recording for Advanced Image and Data Handling, (10 September 1980); doi: 10.1117/12.958648; https://doi.org/10.1117/12.958648