Tsuyoshi Nagano

Thin Optical Head with Flip-Chip Bonded Module for Compact Disc Read Only Memory Drives

A thin optical head for compact disc read only memory drives, whose thickness is 6.9 mm including the objective lens working distance, has been developed. It features a flip-chip bonded module, in which a laser diode chip, a micromirror and a preamplifier chip are integrated on a photodiode chip. The module size is 6 mm(W)×6 mm(D)×1.64 mm(H), and its weight is 0.25 g. Readout operation was successfully carried out for a compact disc, and a 19 ns jitter signal was obtained.

Compact optical head integrated with chip elements for CD-ROM drives

A compact optical head for CD-ROM drives, integrated with a laser diode chip, a photodiode chip, and a holographic optical element in a small optical module, using hybrid assembly technique, has been developed. The module size is 7.5 mm (W) X 8 mm (D) X 3 mm (H), and its weight is 0.6 g. The validity of this optical head design has been demonstrated by successful readout operation for a compact disc.

OPTICAL MODULE USING DOUBLE-SIDED POLARIZING DIFFRACTIVE OPTICAL ELEMENT FOR DIGITAL VERSATILE DISC DRIVES

Digital versatile discs (DVDs) promise to provide excellent multimedia storage for both entertainment and computer use. In this paper, we report a newly designed optical module for use in DVD systems. It consists of a laser diode chip, a photodiode chip, a compound prism, and a double-sided polarizing diffractive optical element (DOE). The double-sided polarizing DOE provides high total light power efficiency (here 78%) that a DVD system requires because of its very small operational margin. The developed optical module has dimensions 9.5 mm(W)×4.2 mm(D)× 6.7 mm(H) and weighs 0.55 g. Its practicality has been demonstrated in successful DVD readout operations, and it is expected to provide the same compact, inexpensive drive that optical modules provide in compact disc (CD) systems.

Compact Magneto-Optical Head Module Integrated with Chip Elements using Double Holograms

A compact magnetooptical head module integrated with chip elements, which uses a polarizing grating and a holographic optical element, has been developed. The module size is W14.4 mm x D5.6 mm X H13 mm. A readout experiment for a magneto-optical disk has been carried out employing a 685 nm laser diode. Carrier-to-noise ratio of more than 45 dB has been obtained under quadruple capacity conditions compared with the first-generation ISO (International Organization for Standardization) standard. Alignment tolerance was also investigated.