Spallas J P, Hostetler R E, Sommargren G E, Kania D R
Appl Opt. 1995 Oct 1;34(28):6393-8. doi: 10.1364/AO.34.006393.
Interferometric testing at the design wavelength is required for accurately characterizing the wave front of an imaging system operating in the extreme ultraviolet. The fabrication of point-diffraction interferometer apertures for extreme ultraviolet wave-front aberration analysis is described. The apertures are formed in a 200-nm-thick low-pressure chemical-vapor-deposited Si(3)N(4) film and vary in size from approximately 0.10 to 0.50 µm to generate a reference wave front of varying numerical aperture. A graded absorber overcoat is used to control the intensity of the aberrated wave front.Optimal fringe contrast can be obtained when the aperture that provides the maximum uniformity and contrast in the interference plane is selected.
在极紫外波段工作的成像系统的波前精确表征需要在设计波长下进行干涉测量测试。本文描述了用于极紫外波前像差分析的点衍射干涉仪孔径的制造方法。这些孔径形成于厚度为200纳米的低压化学气相沉积Si(3)N(4)薄膜中，尺寸从约0.10微米到0.50微米不等，以产生具有不同数值孔径的参考波前。使用渐变吸收涂层来控制像差波前的强度。当选择在干涉平面中提供最大均匀性和对比度的孔径时，可以获得最佳条纹对比度。
