Thermo-optical data writing process and data medium for performing this process

Claim 1

A thermo-optical data writing process using a focused radiation beam intensity modulated to write in data in the form of topographic features protruding from portions of the recordable surface of a recording medium at which the impact of said beam produces a sharply focused illumination, said process comprising the steps of: forming said recording medium of a layer of organic material undergoing thermal degradation above a predetermined temperature threshold with production of gas, said layer being flanked on one side with a thermal triggering layer of a ductile material wherein said topographic features are permanently recorded as a result of local evolution of said gas and loss of adhesion between said layers causing plastic stretching of said ductile metal below its elongation at break, said recording surface corresponding to said thermal triggering layer, said organic material layer being further flanked on its other side with supporting means not liable to substantially reflect radiation impinging from said thermal triggering layer; using an intermediate metal layer for firmly affixing said thermal triggering layer to said layer of organic material; and causing said beam to strike said thermal triggering layer to selectively trigger said thermal degradation from a heating consisting in the direct conversion of an amount of radiant energy from said focused radiation beam to produce, once optically absorbed, enough localized surface heating of said organic material layer to raise the temperature above said threshold thereby providing said topographic features in accordance with said thermal degradation.