OPTICAL MASS MEMORY EMPLOYING AMORPHOUS THIN FILMS

摘要

This optical mass memory utilizes an amorphous semiconductor thin film which can be switched between a generally amorphous or disordered state and a crystalline or more ordered state by applying a laser beam. The laser beam is modulated and scanned across the amorphous film to record and erase information by switching the state of certain regions of the film. The same laser beam modulator and scanner can be used to read the information stored on the film by detecting whether the film is in the amorphous or crystalline state at any given location. The laser beam is composed of at least two frequencies, one of which is absorbed by the amorphous film and is used to write and also erase information on the film. The amorphous film is transparent to the other frequency and the transmission of this frequency is used to determine whether the film is in the crystalline or amorphous state at any given location thereby reading out the information recorded therein.