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A recent development of mirrors is reviewed in this letter. For some applications, such as the hard X-ray telescope, polarization measurements in synchrotron radiation facilities, extreme ultraviolet (EUV) solar observations, and dense plasma diagnostics in China, a series of non-periodic novel multilayers with special performance are developed. X-ray supermirror, EUV broadband polarizer, EUV wide-angular mirror, and double period Kirkpatrick-Baez (K-B) mirror are successfully designed by using different multilayer stack structures. OCIS codes: 310.0310, 340.0340, 350.1260. doi: 10.3788/COL201008S1.0163.

To develop high quality dispersion optics in the X-ray region, the sliced multilayer transmission grating is examined. Dynamical diffraction theory is used to calculate the diffraction property of this volume grating. A WSi2/Si multilayer with a d-spacing of 14.3 nm and bi-layer number of 300 is deposited on a superpolished silicon substrate by direct current magnetron sputtering technology. To make the transmission grating, the multilayer is sliced and thinned in the cross-section direction to a depth of 23-25 μm. The diffraction efficiency of the grating is measured at E = 8.05 keV, and the 1st-order efficiency is 19%. The sliced multilayer grating with large aspect ratio and nanometer period can be used for high efficiency and high dispersion optics in the X-ray region.

Influence of interface roughness on the reflectivity of Tungsten/boron-carbide (W/B4C) multilayers varying with bi-layer number, N, is investigated. For W/B4C multilayers with the same design period thickness of 2.5 nm, a real-structure model is used to calculate the variation of reflectivities with N=50, 100, 150, and 200, respectively. Then, these multilayers are fabricated by a direct current (DC) magnetron sputtering system. Their reflectivity and scattering intensity are measured by an X-ray diffractometer (XRD) working at Cu K\alpha line. The X-ray reflectivity measurement indicates that the reflectivity is a function of its bi-layer number. The X-ray scattering measured results show that the interface roughness of W/B4C multilayers increases slightly from layer to layer during multilayer growing. The variation of the reflectivity and interface roughness with bi-layer number is accurately explained by the presented real-structure model.

Band structures of one-dimensional (1D) photonic crystals (PCs) containing dispersive left-handed metamaterials are studied theoretically. The results show that the structure possesses a type of photonic band gap originating from total internal reflection (TIR). In contrast to photonic band gaps corresponding to zero average refractive index and zero phase, the TIR gap exhibits sharp angular effect and has no polarization effect. It should also be noted that band structures of transverse electric (TE) and transverse magnetic (TM) mode waves are exactly the same in the PCs we studied.

Intrinsic stresses of carbon films deposited by direct current (DC) magnetron sputtering were investigated. The bombardments of energetic particles during the growth of films were considered to be the main reason for compressive intrinsic stresses. The values of intrinsic stresses were determined by measuring the radius of curvature of substrates before and after film deposition. By varying argon pressure and target-substrate distance, energies of neutral carbon atoms impinging on the growing films were optimized to control the intrinsic stresses level. The stress evolution in carbon films as a function of film thickness was investigated and a void-related stress relief mechanism was proposed to interpret this evolution.