Shearing Interferometers using diffraction gratings as elements wavefront division

我们研制了两种利用衍射光栅的剪切干涉仪。一种是采用双周期衍射光栅。光栅具有两个彼此非常接近的周期。另一种干涉仪采用四个相同周期的衍射光栅，在双周期光栅系统中，衍射角的不同产生剪切像。此外，由于由于衍射角的差异而在剪切图像上出现周期性的条纹图案，因此可以借助于傅立叶分析来精确地分析干涉条纹的相位分布。我们制作了一套用于光学CT的双周期光栅剪切系统，用来测量位相型物体的折射率分布。此外，还对剪切干涉仪和传统双光束干涉仪重建折射率的误差进行了讨论。讨论结果表明，共用式光学CT系统具有一定的优越性， ...更多信息 提出了一种利用四个衍射光栅的白色光剪切干涉仪。剪切干涉仪的灵敏度与剪切量成比例，并且剪切量取决于衍射角，在小衍射角的情况下，该衍射角与光的波长近似成比例。当通过使用具有小间隔的一对光栅产生剪切图像时，干涉光束之间的相位差不依赖于光的波长。然后通过在位相物体前后设置光栅对，实现了白色光源的剪切干涉。我们用四个光栅和一个卤素光源制作了一个简单的共享干涉仪。所得到的干涉条纹图案不允许相干噪声，条纹对比度接近0.5，这对应于理想值。通过移动其中一个光栅实现了相移技术的灵敏相位分析，并将四光栅系统的思想应用于X射线干涉仪。我们用单畴硅晶体制作了四片硅薄片X射线干涉仪。少

We developed two types of shearing interferometers using diffraction gratings. The one uses a double period diffraction grating. The grating has two periods which are very close to each other. The other interferometer uses four diffraction gratings with the same grating period.In the double period grating system, the difference in diffraction angles produces shearing images. Moreover, since a periodic fringe pattern appears on the shearing image due to the difference in diffraction angles, phase distribution of the interference fringes can be analyzed accurately with a help of Fourier analysis. We made an shearing system with the double period grating for optical CT to measure refractive-index distribution of a phase object. Moreover some discussions were made about errors in refractive-indices reconstructed from the shearing interferometer and the conventional two-beam interferometer. The discussion results an advantage of the sharing type used for the optical CT system.On the other h … More and, we proposed a white light-shearing interferometer using the four diffraction gratings. Sensitivity of a shearing interferometer is proportional to amount of the shear, and the shear amount depends on the diffraction angle which is in proportion to the wavelength of light approximately in case of a small diffraction angle. When the shear image is produced by using a couple of the gratings with a small separation, the phase difference between the interfering light beams does not depend on the wavelength of light. Then the shearing interferometer for a white light source is realized by setting the couple of gratings in front and back of the phase object. We made a simple sharing interferometer with 4 gratings and a halogen light source. The obtained interference fringes pattern did not allow coherent noise and the fringe contrast was close to 0.5 which corresponded to the ideal value. The phase shift technique for a sensitive phase analysis was realized by moving one of the gratings.Moreover, the idea of the four gratings system is applied to X-ray interferometer. We made a X-ray interferometer with four silicon thin-blade which are made from a single domain silicon crystal. Less