Blue/DVD/CD compatible optical head

Area of Science:

• Optical Engineering
• Data Storage Technologies

Background:

• Digital Versatile Disc (DVD) and Compact Disc (CD) compatibility is crucial for next-generation optical storage.
• High-density optical disk systems require advanced optical heads and precise aberration correction.

Purpose of the Study:

• To evaluate the disc-read compatibility of two high-density optical disk system options using blue laser diodes.
• To assess the performance of optical heads with multiple laser diodes and adaptive aberration correction.

Main Methods:

• Utilized an optical head with three laser diodes (405 nm, 660 nm, 785 nm).
• Implemented an objective lens magnification change for spherical aberration correction due to varying protective layer thickness (0.6 mm for Option 1, 0.1 mm for Option 2).
• Employed a wavelength-selective aperture to control the numerical aperture (0.65 for Option 1, 0.85 for Option 2).

Main Results:

• Both Option 1 (HD DVD) and Option 2 (Blu-ray Disc) demonstrated compatibility with DVD and CD formats.
• Option 1, with a 0.65 numerical aperture and 0.6 mm disc, was found to be more preferable.
• Option 2, featuring a 0.85 numerical aperture and 0.1 mm disc, was deemed acceptable for compatibility.

Conclusions:

• High-density optical disk systems utilizing blue laser diodes can achieve backward compatibility with existing optical media.
• Adaptive optical head designs effectively correct for spherical aberrations arising from different disc protective layer thicknesses.
• While Option 1 offers superior preference, Option 2 presents a viable alternative for achieving disc compatibility.