Weissman E M, Post D
Virginia Polytechnic Institute & State University, Department of Engineering Science & Mechanics, Blacksburg, Virginia 24061, USA.
Appl Opt. 1982 May 1;21(9):1621-3. doi: 10.1364/AO.21.001621.
The theoretical upper limit of moire interferometry is approached as the reference grating pitch approaches lambda/2 and its frequency approaches 2/lambda. This work demonstrates the method at 97.6% of the theoretical limit. A virtual reference grating of 4000 lines/mm (101,600 lines/in.) was used in conjunction with a phase type reflection grating of half of that frequency on the specimen. Sensitivity was 0.25 microm/fringe (9.8 microin./fringe). In-plane displacement fringes of excellent definition were obtained throughout the 76 x 51-mm (3 x 2-in.) field of view. They were very closely packed, exhibiting a maximum fringe density of 24 fringes/mm (610 fringes/in.). Effectiveness of moire interferometry near the theoretical limit was proved.
当参考光栅间距接近λ/2且其频率接近2/λ时，莫尔干涉测量法的理论上限得以趋近。这项工作展示了该方法达到理论极限的97.6%。使用了4000线/毫米（101,600线/英寸）的虚拟参考光栅，并结合了样品上频率为其一半的相位型反射光栅。灵敏度为0.25微米/条纹（9.8微英寸/条纹）。在整个76×51毫米（3×2英寸）的视场中获得了清晰度极佳的面内位移条纹。它们排列非常紧密，最大条纹密度为24条纹/毫米（610条纹/英寸）。证明了莫尔干涉测量法在接近理论极限时的有效性。
