光學系統之動態最佳化:光學補償之Jitter控制單元

高解析度之光學遙測技術為目前衛星發展之主流，但是衛星本身運動所造成的抖動效應﹝Jitter﹞將會大幅減低高解析度遙測酬載的影像品質。傳統上， Jitter 大多由衛星本體控制；雖然目前的衛星設計與製作技術越來越精良，但 Jitter 之效應只能盡量減至最小，仍無法完全避免。光學遙測儀器在進行照相時，衛星產生的任何 Jitter 效應，都將會使得影像品質﹝如MTF ─ Modulation Transfer Function 等﹞降低。所以本實驗提出一套光學補償之 Jitter 控制系統，同步偵測並控制補償 Jitter 效應。　　本實驗採用一較簡化之架構，以驗證光學補償 Jitter 控制單元之可行性。將以一穩定之氦氖雷射﹝He-Ne Laser﹞光源作為入射光線，並打入放置在喇叭﹝Speaker﹞上之鍍銀鏡片﹝Silvering Reflection Mirror﹞，加入電壓至喇叭上使喇叭產生震動，經由喇叭震動而產生光偏移，藉此模擬 Jitter 之效應。並藉由偵測此光線在 Jitter Sensor 上所形成的光斑之偏移量，經由電腦運算輸出控制 Compensator ﹝即Scanner﹞所需旋轉的角度，以補償衛星之抖動。　　在進行此實驗時，我們只使用了單一光源。一方面是因為經費問題，所以在此實驗進行時並沒有光學遙測系統以及成像裝置；另一方面是假如加入成像裝置會造成整體系統的複雜度以及實驗器材架設之困難度大幅提升。因此我們僅針對此單一光源施以 Jitter 之效應，並使用光學補償 Jitter 控制單元來進行即時補償。關鍵詞—光學遙測技術、抖動、氦氖雷射、光學補償、喇叭、鍍銀鏡片、光偏移。

關鍵字

光學遙測技術；抖動；氦氖雷射；光學補償；喇叭；鍍銀鏡片；光偏移

並列摘要

High-resolution optical remote sensing has been one of the major trends amid the development of satellite-related technologies. The jitters of the satellite, however, degrade the image quality of the optical remote sensing system. Traditionally, the jitters are controlled and suppressed by the satellite itself. Nevertheless, they can only be minimized instead of being eliminated, even though the designs and manufacturing techniques of satellites have improved during the past few decades. Any jitter experienced by the satellite definitely downgrades several imaging parameters, such as the MTF (Modulation Transfer Function), etc. This experiment will focus on developing a jitter control unit using optical compensation , which detects the jitter amount and implement the compensation accordingly. 　　We used a simple structure in the experiment to verify the feasibility of the jitter control unit using optical compensation. We used a steady He-Ne Laser to be the reference light source which launched into the silvering reflection mirror which was on the speaker. We inputted voltage to the speaker to generate vibration, the light fluctuation is generated through the speaker to imitate the jitter. The jitter sensor detected the light fluctuation amount and the computer calculated the amount to decide how much the compensator have to rotate, to compensate the jitter on the satellite. 　　We used only one light source in the experiment. Because the fund was finite, we did not add the optical remote system and image system to the experiment. In the other hand, if we add the two systems to the experiment, the experiment structure would be very complicated. So we just used one light source to imitate the jitter effect, and used optical compensation jitter control unit to proceed real-time compensation.

並列關鍵字

Optical Remote Sensing, ； Jitter ； He-Ne Laser ； Optical Compensation ； Speaker, Silvering Reflection Mirror ； Light fluctuation

參考文獻

[1] T. Bifano, J. Perreault, P. Bierden, and C. Dimas, “Micromachined deformable mirrors for adaptive optics,” in Proceedings of SPIE Vol. 4825 (2002), pp.10-13.

[4] R. K. Tyson and B. W. Frazier, “Microelectromechanical system programmable aberration generator for adaptive optics,” Applied Optics, Vol. 38, No. 1, pp. 168-178, 1999.

[5] C. Paterson, I. Munro, and J. C. Dainty, “A low cost adaptive optics system using a membrane mirror,” Optics Express, Vol. 6, No. 9 pp. 175-185, 2000.

[6] L. Zhu et al., “Wave-front generation of Zernike polynomial modes with a micromachined membrane deformable mirror, ” Applied Optics, Vol. 38, No. 28, pp.6019-6026, 1999.

[8] Enrique J. Fernández and Pablo Artal, “Membrane deformable mirror for adaptive optics: performance limits in visual optics,” OPTICS EXPRESS, Vol. 11, No. 9, pp.1056-1069, May 2003

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光學系統之動態最佳化:光學補償之Jitter控制單元

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