RISS 검색 - 국내학술지논문 상세보기

다국어 초록 (Multilingual Abstract)

An adaptive optics system can be simulated or analyzed to predict its closed-loop performance. However,this type of prediction based on various assumptions can occasionally produce outcomes which are farfrom actual experience. Thus, every adaptive optics system is desired to be tested in a closed loop onan optical test bench before its application to a telescope. In the close-loop test bench, we need anatmospheric simulator that simulates atmospheric disturbances, mostly in phase, in terms of spatial andtemporal behavior. We report the development of an atmospheric turbulence simulator consisting of twopoint sources, a commercially available deformable mirror with a 12×12 actuator array, and two randomphase plates. The simulator generates an atmospherically distorted single or binary star with varying stellarmagnitudes and angular separations. We conduct a simulation of a binary star by optically combining twopoint sources mounted on independent precision stages. The light intensity of each source (an LED witha pin hole) is adjustable to the corresponding stellar magnitude, while its angular separation is preciselyadjusted by moving the corresponding stage. First, the atmospheric phase disturbance at a single instance,i.e., a phase screen, is generated via a computer simulation based on the thin-layer Kolmogorov atmosphericmodel and its temporal evolution is predicted based on the frozen flow hypothesis. The deformable mirroris then continuously best-fitted to the time-sequenced phase screens based on the least square method.
Similarly, we also implement another simulation by rotating two random phase plates which were manufacturedto have atmospheric-disturbance-like residual aberrations. This later method is limited in its abilityto simulate atmospheric disturbances, but it is easy and inexpensive to implement. With these two methods,individually or in unison, we can simulate typical atmospheric disturbances observed at the Bohyun Observatoryin South Korea, which corresponds to an area from 7 to 15 cm with regard to the Fried parameterat a telescope pupil plane of 500 nm.

참고문헌 (Reference)

1 안교훈, "적응광학계용 37채널 SiC 변형거울을 이용한 파면 보상" 한국광학회 27 (27): 106-113, 2016

2 V. I. Tatarskii, "Wave propagation in a turbulent medium" McGraw-Hall 1961

3 R. G. Lane, "Simulation of a Kolmogorov phase screen" 2 : 209-224, 1992

4 M. K. Giles, "Setting up a liquid crystal phase screen to simulate atmospheric turbulence" 4124 : 89-97, 2000

5 R. W. Wilson, "SLODAR: measuring optical turbulence altitude with a Shack-Hartmann wavefront sensor" 337 : 103-108, 2002

6 J. H. Lee, "Robotic SLODAR development for seeing evaluations at the Bohyunsan Observatory" 2015

7 M. A. van Dam, "Performance of the keck observatory adaptive-optics system" 43 : 5458-5467, 2004

8 B. W. Frazier, "Performance of a compact adaptive-optics system" 43 : 4281-4287, 2004

9 D. L. Fried, "Optical resolution through a randomly inhomogeneous medium for very long and very short exposures" 56 : 1372-1379, 1966

10 T. S. Taylor, "Laboratory simulation of atmospheric turbulence-induced optical wavefront distortion" 34 : 665-669, 2002