Considerations in laser zone texture tool design

Summary form only given. To satisfy the performance requirements of the various media suppliers, it was clearly necessary to build a tool with significant flexibility in bump diameter, bump height, bump spacing, and zone placement. It also appeared that evolution to smaller bump sizes was desirable. To achieve the smallest possible bumps, it was clear that a diffraction limited optical system would be required. To maintain long-term stability and ensure precise focusing on every disk, several motor-actuated electro-optical closed-loop servo systems were employed. This has the additional ease-of-use benefit of allowing menu-driven control of all key bump and zone parameters. The trade-off in this design is that it is more complex optically. The alignment, once completed in manufacturing, has proved to never need adjusting in normal use, because all the vital actuators are servo controlled. It was decided that the entire automation module would be physically separated from the laser and optics processing module. A single two-axis rotary joint robot, capable of >320 disks/h, is employed with a dual-vacuum gripper assembly for handling the disks. Various conveyor or turntable options are available for cassette control. Ultimately, tool throughput is just a cost and complexity decision. Our tool utilizes a single spindle and single process station design. This provides the lowest cost per disk and highest throughput per square foot of clean room space in a highly reliable simple design.