A 0.1 millimeter thick cover layer comprises the Blu-ray Disc’s outermost internal surface, and the recording material resides beneath it. During recording, the laser passes through the cover layer in its path to the recording layer. Absolute uniformity in the thickness of the cover layer is critical to ensuring precise laser tracking, which is required for
reliable performance.

TDK’s exclusive spin coating technology creates a cover layer with nano-precise smoothness, ensuring pure recording perfection. Only TDK utilizes this proprietary spin coating process.