Patent ID: 7236440

Claim:
A high-speed, write-once type optical recording medium comprising at least a recording layer and a light transmission layer formed sequentially on top of a support substrate, wherein that said recording layer is formed by laminating at least two vice-recording layers, each of which comprises one type of metal as a primary component, and irradiation of a laser light that is either blue or an even shorter wavelength, from a side of said light transmission layer, causes diffusion and mixing of primary component metals contained within each of said vice-recording layers, this mixing enables formation of a recording mark based on an irreversible change in reflectance, and recording can be conducted at a recording transfer rate of at least 35 Mbps by using a system in which a thickness of said recording layer is from 3 to 50 nm, a wavelength of said laser light is from 200 to 450 nm, and which utilizes a lens system having an objective lens used for irradiation of said laser light, a numerical aperture of the objective lens being at least 0.8, further wherein at least one layer of said vice-recording layers comprises Al as a primary component, and at least one other layer is provided adjacent to said vice-recording layer comprising Al as a primary component and comprises Sb as a primary component, and irradiation of said laser light causes diffusion and mixing of said Al and Sb contained within each of said vice-recording layers.