METHODS AND APPARATUS FOR SPLITTING, IMAGING, AND MEASURING WAVEFRONTS IN INTERFEROMETRY

摘要

Apparatus for splitting, imaging, and measuring wavefronts with a reference wavefront and an object wavefront. A wavefront-combining element receives and combines into a combined wavefront (66) an object wavefront (58) from an object and a reference wavefront (56). A wavefront-splitting element (80) splits the combined wavefront (66) into a plurality of sub-wavefronts (70a, 70b, 70c, 70d) in such a way that each of the sub-wavefronts (70a, 70b, 70c, 70d) is substantially contiguous with at least one other sub-wavefront. The wavefront-splitting element (80) may shift the relative phase between the reference wavefront and the object wavefront of the sub-wavefronts (70a, 70b, 70c, 70d) to yield a respective plurality of phase-shifted sub-wavefronts. The wavefront-splitting element (80) may then interfere the reference and object wavefronts of the phase-shifted sub-wavefronts to yield a respective plurality of phase-shifted interferograms (74a, 74b, 74c, 74d). An imaging element (76) receives and images the phase-shifted interferograms (74a-d). A computer connected to the imaging element (76) measures various parameters of the objects based on the phase-shifted interferograms (74a-d). Examples of measurements include flow parameters such as the concentrations of selected gaseous species, temperature distributions, particle and droplet distributions, density, and so on. In addition to flow parameters, the displacement (e.g., the vibration) and the profile of an object may be measured.