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Up: THE HYDRA FIBER POSITIONER
To position the fibers, a 3-fingered gripper rides on a 3-axis stage mechanism moving each fiber, one by one, onto the focal plate assembly. The center of the gripper jaw enclosure is optically transparent allowing a gripper camera to ``view" the button placement via illumination from a bank of LED's on the gripper.
The Z-axis, allowing the gripper to pick up and place, rides on a Y-stage which in turn is mounted to a dual drive X-stage. Both X and Y stages are encoded to 2.5m steps (0.024 arc-seconds on the sky). Positional error is estimated to be about 0.2" (20m) rms.