Disk Drive Optical System Operation Under Environmental Stress

A high-performance, field-ready Optical Disk System(1), currently under development at RCA, is designed to meet or exceed the performance capabilities currently required for most remote data collection applications. The system, contained in a single-console unit (Figure 1), includes all disk drive optics and mechanisms, data processing electronics(2), and on-board micro-controller unit. Data is transferred at 20 Mbps continuously or at 40 Mbps in bursts and the user data capacity is 5 x 1010 bits per disk side with no more than 1 in 108 bits in error. Data is recorded (in two parallel channels) using a dual-element CDH-LOC diode laser array. Two-channel operation affords closer track juxtapositioning than is possible with single element devices thus increasing data capacity by as much as fifty percent. A single HeNe laser beam is split into multiple beams by cascaded transmission phase gratings for dual-track readout and radial tracking control. The optical footprint at the recording plane is illustrated in Figure 2.