Simultaneous measurement of phase and spatially variant elliptical polarization of light fields

基于亚波长结构的偏振元件越来越多地在光学中得到应用。一个例子是径向偏振光的产生，其可用于显微镜以产生特别小的旋转对称焦点。然而，除了偏振之外，这样的元件通常影响入射光场的相位。因此，同时测量光场的偏振态和相位是一项重要的任务。到目前为止，相位和偏振只能分别确定，通过斯托克斯测量偏振和干涉测量的相位。然而，当在干涉仪中使用具有空间变化的偏振的光场来确定相位时，在干涉图中存在具有消失对比度的区域，其中物体和参考光束的偏振正交。测量只能在具有良好对比度的区域中进行，并且这些区域彼此的取向不清楚。因此，对于一般偏振光，用标准方法不可能确定整个区域的相位。为了克服这些问题，提出了一种新的测量方法，它可以同时确定的相位和一般，即。e.在一个单一测量过程中光的空间变化椭圆偏振态。该解决方案包括通过参考偏振的附加变化来扩展相移干涉测量的公知过程。通过这种偏振相移干涉术，可以获得关于物波的附加信息。

Polarization elements which are based on subwavelength structures increasingly find applications in optics. An example is the generation of radially polarized light which may be used in microscopy to create particularly small rotationally symmetric foci. Aside from the polarization, however, such elements in general affect the phase of the incident light field. Therefore, the simultaneous measurement of the polarization state and the phase of the light field is an important task. Up to now, phase and polarization can only be separately determined, via Stokes measurements for the polarization and interferometric measurements for the phase. When a light field with a spatially varying polarization is used in an interferometer to determine the phase, however, regions in the interferogram with vanishing contrast exist where the polarizations of object and reference beam are orthogonal. The measurement can only be performed in the regions with good contrast, and the orientation of these regions to each other is not clear. For generally polarized light, a determination of the phase for the whole area is therefore not possible with standard methods. To overcome these problems, a novel measurement method is proposed which enables the simultaneous determination of the phase and a general, i. e. spatially variant elliptical polarization state of light within one single measurement process. The solution consists in extending the well known procedure of phase shifting interferometry by an additional variation of the reference polarization. By means of such a polarization and phase shifting interferometry the additional information about the object wave can be gained.