Switching, logic, & storage OPTICS  vs. the  COMPETITION  This article is based on a panel discussion on Issues in Optical Technologies: Switching, Logic, and Storage, held in Anaheim on May 22 as part of the 1990 Conference on Lasers and Electro-Optics (CLEO®). The five panelists, representing both optical and competing technologies, were: Lynn Hutcheson, Raynet Corp.; Robert Keys, IBM Thomas J. Watson Research Center; John Malinson, Center for Magnetic Recording Research, University of California at Sari Diego; Masud Mansuripur, Optical Sciences Center, University of Arizona; and David A.B. Miller, AT&T Bell Laboratories. An audience of more than 400 people attended and participated in the discussion, chaired by the author, which examined both the positive features of and the challenges facing optical technologies. One literature reference associated with the material discussed by each panelist appears at the end of this article. By Dennis G. Hall  "In my 30 years in magnetic record- ing, optical recording has always been, is today, and will always remain the recording technology of the future," John Malinson, a champion of mag- netic data storage, proclaimed to much laughter. "I feel like the policeman at the party, or the fireman at a fire," he said, making his opinion clear from the very start. "I'm here basically to quench some of your ardor for lasers and optical things ...I'm trying to convince you in 10 minutes flat that magnetic recording is here to stay and nothing is going to displace it." 1 Malinson went on to emphasize three important features of magnetic recording: density, capacity, and data rate. He noted that the areal density in magnetic recording doubles every two to two and one-half years. While current products make use of a density of approximately 100 megabits per square inch (Mbits/in 2 ) , I B M has already demonstrated (1989) in the research laboratory, magnetic disk recording at the density 1.2 gigabits per square inch (Gbits/in 2 ). The fact that magnetic tape is very thin makes high volume densities of information possible. Densities of 10 11 bits/in 3 are regularly achieved in rotary digital audio transport (RDAT) cassettes. "The volume density in magnetic recording will not be sur- passed by anything this century," Malinson predicted. By way of example, Malinson re- viewed the characteristics of a specific magnetic tape (cassette) system, the AMPEX VPR300 Digital Composite Videotape Recorder, which records data onto a cassette at the rate of 148 Mbits/second for up to three and one-half hours, for a cassette capacity of 2 x 10 12 bits (2 terabits). A data rate of 148 Mbits/second exceeds that for a Cray computer by a factor of three, and 2 terabits of data will fill 40 14-inch optical disks recording on both sides, he claimed. Data rates of 300 Mbits/second through a single head are expected soon. The case for optics  Examining the case to be made for optical data storage, 2 Masud Man- suripur divided the field into three areas: read-only memories (ROM), currently used in compact disk and CDROM technologies; archival stor- age, the so-called write-once, read- many (WORM) applications; and erasable drives and media, which use either the magneto-optic or phase change mechanism. All products in the erasable category available today make use of magneto-optics, Man- suripur claimed. An areal density of 10 8 bits/cm 2 (or 645 Mbits/in 2 ) is now available using optical data storage, a density 10 times greater than that in the best magnetic recording product available today, according to Mansuripur. Thus, he notes, the entry-level optical data storage product has a higher areal density than products that are the result of 35 years of R&D in magnetic recording. In contrast to magnetic data stor- age, the read/write head is not in close proximity to the disk in optical stor- age. Mansuripur views this as an advantage for optical recording, since disks can be inserted and removed easily. A portable 5.25 inch optical disk, therefore, acts like a floppy disk, but has a capacity of 600 Mbytes, and can be used at the same data rate and with nearly the same access times as a Winchester magnetic disk system, he explained. Important elements in optical re- cording heads include an aluminum gallium arsenide semiconductor laser, an objective lens, a beam-splitter, a photodetector, and an actuator sys- tem. The actuator moves the objective 18 OPTICS & PHOTONICS NEWS • OCTOBER 1990