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Design of an active focus system for a Mars-bound robotic arm camera

ABSTRACT The Mars Surveyor Spacecraft's Robotic Arm Camera (RAC) is a CCD imager designed to enhance the capability of studyingboth trenched areas and material collected by the craft's Robotic Arm. Because of the wide range of object distances/imagescales desired, an active focus mechanism will be used, capable of imaging from a magnification of 1 : 1 to infinity focus, witha maximum resolution of 23 microns/pixel for Mars surface material samples in the mouth of the scoop. This paper willdiscuss the optomechanical design of the optics, mechanism, and actuator, operational scenarios for the most efficientcollection of the necessary images, and algorithms for selection of images to be returned to earth.Keywords:Optomechanical, camera, autofocus, instrument, Mars 1. INTRODUCTION The Mars Volatiles and Climate Surveyor (MVACS) instrument package to be flown on the Mars SurveyorSpacecraft scheduled for launch in January, 1999, includes a Robotic Arm for collecting and delivering samples to a thermalanalysis instrument. The Robotic Arm Camera, to be mounted at the wrist, will be capable of imaging the contents of thescoop, the interior of the trench and surrounding areas, and even the horizon. Figure 1 .