Ricoh has developed an optical component that reads and writes all disk formats — Blu-ray and HD-DVD, as well as DVD and CD — with one pickup and one objective lens.
The optical device was shown last week at the International Optoelectronics Exhibition near Tokyo. Ricoh intends to offer the device to OEMs by year's end.
The component is a 3.5mm-diameter, 1mm-thick round diffraction plate with minute concentric groves on both sides, which function as a diffraction grating, EE Times reported. The plate is placed between lasers and an objective lens. The diffraction grating is designed to adjust a light beam to an optimum incident ray relative to the objective lens so that light focuses on the proper position for each disk format.
The data layer of Blu-ray resides 0.1mm from the disk's surface, while the HD-DVD data layer is 0.6mm deep from the disk's surface, the same as DVDs. CDs have a data layer depth of 1.1mm from the disk surface.
The device is designed to pave the way for multiformat players and recorders that could identify which format disk is loaded. Based on the disc information, the optical diffraction component would adjust the laser beam with its diffraction grating for each format and pass it to the objective lens. The lens would then form a beam spot at the appropriate depth for each disk format, the report said.
EE Times noted that although the diffraction device works for both reading and writing modes, Ricoh will initially offer the device for disk players only. That's because some laser beam energy is lost at the grating, and using the diffraction device for recording would require a blue laser with higher power than those used in conventional recorders.
