Heil Joachim, Bauer Tobias, Sure Thomas, Wesner Joachim
Leica Microsystems CMS GmbH, Wetzlar, Germany.
Appl Opt. 2006 Jun 20;45(18):4270-83. doi: 10.1364/ao.45.004270.
Full-bandwidth phase-shifting methods as well as band-limited fringe carrier techniques are both problematic when testing high-NA spherical surfaces in Fizeau interferometers. Phase stepping is usually performed by moving a sample and reference sphere relative to each other along the optical axis. At a high NA the method suffers from phase-shift inhomogeneity across the sample surface. Fringe carrier techniques rely on a minimum fringe frequency and call for an off-axis position of the sample, which in turn introduces condenser aberrations. Distortion of the imaging optics generates further apparent aberrations. We propose to combine both principles. The phase shifts are replaced by a set of very low tilts such that the sample is virtually on axis. Initial wavefront estimates are generated by a fringe carrier method. An adaptive Misell-type algorithm combines the interferometric data and iteratively improves the reconstructed wavefront until full spatial bandwidth is achieved.
在菲佐干涉仪中测试高数值孔径（NA）的球面时，全带宽相移方法以及带限条纹载波技术都存在问题。相移通常是通过使样品和参考球沿光轴相对移动来执行的。在高数值孔径下，该方法会出现样品表面相移不均匀的情况。条纹载波技术依赖于最小条纹频率，并要求样品处于离轴位置，这反过来又会引入聚光镜像差。成像光学系统的畸变会产生进一步的明显像差。我们建议将这两种原理结合起来。将相移替换为一组非常小的倾斜度，使得样品实际上处于轴上。初始波前估计通过条纹载波方法生成。一种自适应米塞尔型算法将干涉测量数据结合起来，并迭代地改进重建的波前，直到获得完整的空间带宽。
