Design Differences between the Pan-STARRS PS1 and PS2 Telescopes

The PS2 telescope is the second in an array of wide-field telescopes that is being built for the Panoramic-Survey Telescope and Rapid Response System (Pan-STARRS) on Haleakala. The PS2 design has evolved incrementally based on lessons learned from PS1, but these changes should result in significant improvements in image quality, tracking performance in windy conditions, and reductions in scattered light. The optics for this telescope are finished save for their coatings and the fabrication for the telescope structure itself is well on the way towards completion and installation on-site late this year (2012). The most significant differences between the two telescopes include the following: secondary mirror support changes, improvements in the optical polishing, changes in the optical coatings to improve throughput and decrease ghosting, removal of heat sources inside the mirror cell, expansion of the primary mirror figure control system, changes in the baffle designs, and an improved cable wrap design. This paper gives a description of each of these design changes and discusses the motivations for making them.