# Improved kinematic mount design for bar type reference mirror for profilometric measurement large optical surface

• Jung, Kil-Jae (Space Optics Laboratory, Dept. of Astronomy, Yonsei University) ;
• Yang, Ho-Soon (Korea Research Institute Standards and Science) ;
• Rhee, Hyug-Gyo (Korea Research Institute Standards and Science) ;
• Jyun, Byoung-Hyug (Korea Research Institute Standards and Science) ;
• Lee, Yun-Woo (Korea Research Institute Standards and Science) ;
• Kim, Sug-Whan (Space Optics Laboratory, Dept. of Astronomy, Yonsei University)
• Published : 2010.04.15

#### Abstract

Our previous study used a bar-type reference mirror to measure the relative distance to the target surface. The target measurement accuracy was required to $1{\mu}m$ PV for aspheric optical surface up to 1m in diameter. Earlier system suffers from the reference surface deformation when the measuring part moves. In order to reduce the deformation, measuring part and the reference part separated from each order in the new design. This system utilizes a kinematic support assembly using invar flexure to minimize the reference surface deformation under gravity and vibration. The surface deformation requirement of reference mirror is defined as of $0.2{\mu}m$ under gravity and 40Hz vibration. The finite element results, shows reference mirror deformation of $0.164{\mu}m$. The first resonance mode was computed to analysis 46.05Hz for reference part and 43.44Hz for measuring part. Thesis satisfies the frequency requirement.