State of the art in optical heads and systems

Abstract

Current head technology relies on the use of many discrete components, 4 to 5 mm in diameter, mounted in a rigid enclosure. To reduce the moving mass and improve access performance, only the final objective lens, a folding mirror, and the fine actuator are moved along an optical axis by the remainder of the optics, which is stationary. These optical components, while highly miniature by today's standards, result in a rather bulky head assembly that is 15 to 25 mm high. A head of this size will easily fit within a drive form-factor as small as 3.5″. Increasing box capacity by expanding to more recording surface and heads, however, will require additional miniaturization. Integrated optical heads using waveguides and grating couplers are receiving serious attention as a possible solution. In addition, they are expected to ease alignment requirements, enhance manufacturability/cost and improve head reliability and stability.