應用數位微鏡於自適應光學系統的波前感測與校正技術研究

Abstract

自適應光學（Adaptive Optics, AO）技術用於補償大氣湍流等因素引起的波前畸變，顯著提升光學系統的成像質量和分辨率。近年來，AO技術在天文學、衛星成像、光通信和生物醫學等領域蓬勃發展。然而，傳統AO系統使用變形鏡(Deformable Mirror)或液晶空間光調制器(Spatial Light Modulator，SLM)進行波前校正，存在成本高、耐用性低和溫度敏感等問題。 本研究提出用於雷射光波前補償與校正，基於數位微鏡(Digital Micromirror Device，DMD)之AO系統，其中DMD結合全像術(Holography)作為波前校正系統，並以研究團隊先前所提出之波前感測器SPARROW為靈感開發出DMD輔助徑向剪切干涉儀進行波前感測。DMD具備高反應速度、寬頻響應及高耐用性等優勢，結合全像術能有效進行波前校正並改善傳統徑向剪切干涉儀的測量速度。實驗架設中我們使用633nm波長之氦氖雷射經過空間濾波器及准直透鏡作為完美波前，通過擾動區域後，以DMD作為波前校正系統，我們使用之DMD為DLP4500.45 WXGA DMD有著 之高分辨率及 的高反應時間補償擾動波前，而補償波前則是利用二進制電腦生成全像術(Computer Generated Holography，CGH)進行波前振幅、相位及全像圖空間頻率獨立調控。後端徑向剪切干涉儀中僅利用一片剪影板及一個感光元件同時取得垂直方向及水平方向之剪切干涉條紋，並且利用DMD生成傾斜波前改良傳統鏡向剪切干涉儀中之相移機制，形成DMD輔助徑向剪切干涉儀進行波前重建。 實驗結果顯示，基於DMD的AO系統可成功量測未知波前並且進行校正，為雷射系統和精密光學測量提供了新的技術路徑。總結來說，本研究所提出之系統能在未來波前校正和波前感測方面展現了優越的性能，具有廣闊的應用前景。

Adaptive Optics (AO) technology is used to compensate for wavefront distortions caused by atmospheric turbulence, significantly improving the imaging quality and resolution of optical systems. In recent years, AO has been extensively applied in astronomy, satellite imaging, optical communications, and biomedical fields. However, traditional AO systems using deformable mirrors (DM) or liquid crystal spatial light modulators (SLM) are costly, have low durability, and are sensitive to temperature. This study proposes an AO system for laser wavefront compensation and correction based on Digital Micromirror Device (DMD) technology. DMD, combined with holography, serves as the wavefront correction system, inspired by our previously developed wavefront sensor, SPARROW, to develop a DMD-assisted lateral shearing interferometer for wavefront sensing. DMD features high response speed, wide spectral response, and high durability. In the experimental setup, we use a 633nm HeNe laser through a spatial filter and collimating lens as a perfect wavefront. After passing through the perturbation area, the DMD-based wavefront correction system, utilizing the DLP4500 .45 WXGA DMD with resolution and response time, compensates for the distorted wavefront using computer-generated holography (CGH) for independent control of wavefront amplitude, phase, and spatial frequency of holograms. The lateral shearing interferometer in the back end uses a single shear plate and a CMOS to simultaneously capture horizontal and vertical shear interference fringes. The DMD-generated tilt wavefront improves the phase-shifting mechanism of traditional shearing interferometers, forming a DMD-assisted lateral shearing interferometer for wavefront reconstruction. Experimental results demonstrate that the DMD-based AO system can successfully measure and correct unknown wavefronts, providing a new technological pathway for laser systems and precision optical measurements. In conclusion, the proposed system exhibits superior performance in wavefront correction and sensing, offering broad application prospects.