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Analytic Calculation Method of Zoom Loci for Zoom Lens System with Infinite Object Distance

무한물점용 줌 렌즈 광학계의 줌 궤적에 대한 해석적 계산법

  • Oh, Jeong Hyo (Department of Physics, Graduate School, Hannam University) ;
  • Ryu, Jae Myung (Department of Optical Engineering, Kumoh National Institute of Technology) ;
  • Jo, Jae Heung (Department of Optics and Sensors/Department of Physics(Graduate School), Hannam University)
  • 오정효 (한남대학교 대학원 물리학과) ;
  • 류재명 (국립금오공과대학교 광시스템공학과) ;
  • 조재흥 (한남대학교 공과대학 광.센서공학과/대학원 물리학과)
  • Received : 2013.04.11
  • Accepted : 2013.04.26
  • Published : 2013.06.25

Abstract

In case of the optical camera system with an infinite object distance, optical designs different from previous systems are required to speed up the auto-focus. As the number of lens groups is increased due to this, the conventional analytic method found it difficult to calculate the locus, and even the one-step advanced calculation method also had the trouble of taking a lot of time. In this paper, we suggested an analytic method for calculating the zoom loci by analyzing movement of one or two groups for situations corresponding to the given back focal length and effective focal length after taking a spline interpolation for each lens group. With this method, we would not only calculate the analytic zoom loci without iterations in every optical system without placing a limit on the group number at the zoom lens systems with the infinite object distance, but we would also show the utilities of this method through many examples.

무한물점으로 취급하는 카메라 광학계의 경우, 자동초점(auto-focus) 속도를 빠르게 하기 위해 기존 광학계와 다른 형태로 광학설계를 하게 된다. 이 때문에 군의 개수가 늘어나므로, 기존의 해석적인 방법으로는 궤적 계산이 어렵고, 또한 수치해석적인 방법은 시간이 많이 걸리는 단점이 있다. 본 논문에서는 각 군을 스플라인 보간을 한 뒤, 주어진 뒤정점초점거리와 유효초점거리를 만족하도록 1개 또는 2개 군의 이동량을 해석적으로 구해 줌 궤적을 계산하는 해석적인 방법을 제안하고 이를 유도한다. 이 방법은 무한물점용 줌 렌즈 광학계에서 군수의 제한 없이 모든 광학계에 대해 반복적인 계산없이 해석적인 궤적을 구할 수 있으며, 다양한 예제를 통하여 그 효용성을 보였다.

Keywords

References

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  2. Evaluation of a Corrected Cam for an Interchangeable Lens with a Distance Window vol.18, pp.1, 2014, https://doi.org/10.3807/JOSK.2014.18.1.023
  3. Optical Design and Fabrication of a Large Telephoto Zoom Lens with Fixed f/2.8 and Light Autofocus Lens vol.19, pp.6, 2015, https://doi.org/10.3807/JOSK.2015.19.6.629