Header for SPIE use

At the f/2 focus, a spine tilt of 1/20 radian is just acceptable and requires the spines be 140 mm long. Two basicmechanisms for tilting and holding such a spine have been investigated experimentally. The first uses three commercial miniature linear actuators set parallel and linked to the base of the spine through simple flexures. A prototype has been builtand demonstrated to perform satisfactorily. Another approach is to mount the spine on a ball joint and drive it directly in tip and tilt using a bending piezo impact drive. A prototype of this form has been built; initial tests are promising. Keywords: Optical fibers, spectroscopic feed, Subaru telescope, miniature mechanism, robotic positioner, Nanomotor,piezo impact drive 1. INTRODUCTION In conjunction with plans to provide multi-object spectroscopy from the f/2 prime focus of the Japanese 8.2 metre diametertelescope (Subaru) on Mauna Kea, a fiber positioner for up to about 400 fibers is required. The 0.5 degree field of the telescope covers a diameter of about 143 mm, giving a physical field area about 1/10 that of the two degree field (2dF) fiberpositioner on the Anglo-Australian Telescope which als