发明授权
US4839251A Photo-mask for use in manufacturing an optical memory disc, a method for making the photo-mask and a method for manufacturing the optical memory disc 失效
用于制造光存储盘的照相掩模,用于制造光掩模的方法和用于制造光存储盘的方法

Photo-mask for use in manufacturing an optical memory disc, a method for
making the photo-mask and a method for manufacturing the optical memory
disc
摘要:
A photo-mask for use in manufacturing an optical memory disc has a substrate having a disc shape and made of a transparent material, and a film deposited on the substrate and formed with a predetermined pattern of grooves extending spirally or concentrically to the center of the disc shaped substrate such as to leave a thin film at the bottom of the grooves, and a number of microscopic pits in the form of minute indentations with a predetermined spacing aligned along the grooves so as to substantially leave no film at the bottom of the indentations. Thus, a light which has passed through the thin film at grooves is weakened and a light which has passed through the indentations loses substantially no power, and a light applied elsewhere on the film is cut off. The photo-mask is made through the steps of depositing an opaque film on a substrate having a disc shape and made of a transparent material, impinging a first laser at places where the grooves are to be formed, and impinging a second laser at places where the pits are to be formed. The first laser is weaker in power than the second laser.
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