变线距光栅线密度的干涉测量

变线距光栅在同步辐射装置、激光核聚变装置上有着广阔的应用前景，它的制作和检测方法尚未成熟。用干涉法测量变线距光栅的线密度，给出了测量原理、实验中的光路、数据处理的方法、测量结果。在待测光栅表面，衍射光干涉条纹的数量和密度是入射光干涉条纹和倍增后光栅的刻线之差。采用共光路的方案，使光路具有很强的抗干扰能力。用中值滤波消除干涉图像中的干扰。针对不同的干涉条纹，讨论和比较了两种测量方法，提出相对密度不变性。证明了干涉法完全可以用于变线距光栅的线密度测量，并能达到一定的精度，初步解决了检测问题，认为这种方法也可以用于变线密度光栅的加工中。

Interferometric Measurement of the Line Density of Varied-Line-Space Gratings

Varied-line-space grating is very useful in synchrotron radiation devices and laser fusion devices, but there are no good ways to measure them. The line density of varied-line-space gratings have been measured by using interferometry. The principle and geometry are introduced, the methods of data processing and the results are given. On the surface of grating to be tested, quantity and density of diffracted light interferometric fringes are difference of interferometric fringes of incident light and grating groove quantity multiplied. Two sets of waves are in the common path, it is easier to make adjustment and measurement. Interference in interferometric image is removed by mid-value filtering method. Two projects are put forward for different interference fringes. The invariance of relative density is brought forward. The grating diffracts two coherent incident waves, the fringes appear, the density relates to groove density, if the incidence angles and the diffraction orders and the position of fringes are known, the groove density can be calculated. The method can satisfy the requirements of varied-line-space gratings, and it is suitable in the measurement of varied-line-space gratings and can reach some precision. Finally, the method is suggested into fabrication of holographic varied-line-space gratings.