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Optics and optical subsystems are playing a larger role in consumer electronics. With that role comes extraordinary developments in size and weight reduction as well as high volume manufacturing methods, driving down both cost and size. Optical elements, as well as lasers and detectors will be fabricated lithographically and configured using the packaging technologies developed for ICs and multi-chip modules. A miniature laser-based optical sensor recently developed for a particularly low cost, high volume application takes advantage of these advanced fabrication methods. The application is the LS120TM disk drive which features a conventional magnetic floppy disk with an optical tracking servo to permit a much finer magnetic track pitch on the media. The 120 MB disk drive has been in the desktop computer market for several years. but the recent effort to develop a smaller version for laptop and notebook computers required major size and mass reduction in the optical sensor. For desktop personal computers, the standard drive bay is 25.4mm high. The standard LSl201M drive features an optical tracking head which is large. with macroscopic lenses, difIractive elements., lasers and detectors which are assembled into a molded chassis [1]. Extension of LS120Thi technology to laptop computers required reducing the drive height to fit in a 12.7 mm slot. This necessitated a significant reduction in the size and mass of the optics head. The device would be required to have the structural integrity to carry the electrical leads for servo interfacing while maintaining precise alignment to the magnetic head. The new size and mass constraints required a fundamental change from the conventional optical system construction. The new sensor was produced using Integrated Micro-Optical System (IMOS) technology [2]. In IMOS. the optical elements are lithographically generated with integrated alignment and bonding features. The source and detector elements are assembled into the system at the chip level, using flip-chip techniques to mechanically and electrically connect them.
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