Shigetaro Ogura

Comparison Among Multilayer Soft X-Ray Mirrors Fabricated By Electron Beam, Dc-, Rf-Magnetron Sputtering And Ion Beam Sputtering Deposition

Multilayer Mo/Si mirrors have been fabricated by various physical vapor deposition methods. The best mirror fabricated by RF-magnetron sputtering showed a reflectivity of 57.8% at an incident angle of 25° and at a wavelength of 12.66 nm with synchrotron radiation reflectometer. The characteristics of fabricated multilayer mirrors have been measured using transmission electron microscope for surface and cross-sectional micrographs, electron diffraction for crystalline nature, small-angle x-ray diffractometer and synchrotron radiation reflectometer for reflectivity. Particularly, the dependencies of deposition parameters of Ar pressure and input power in RF-magnetron sputtering and substrate temperature in electron beam deposition in ultra high vacuum, have been investigated. The crystalization of Mo layers is clearly admitted for the mirrors by DC-and RF-magnetron sputtering. Surface roughness is minimum for the mirrors by RF-magnetron sputtering and ion beam sputtering. A possible reason of low reflectivity for the mirrors by ion beam sputtering is discussed from the resluts of additional analysis.

Efficient, damage resistant LiNbO3 acousto‐optic waveguide deflector

An efficient, damage resistant, guided wave deflector in LiNbO3 has been fabricated by a combination of titanium diffusion, proton exchange in benzoic acid with lithium benzoate, and post‐annealing processes. The stability of the waveguide has been confirmed using x‐ray rocking curves. The insertion loss of interdigital transducer and the diffraction efficiency were found to depend on the wave number of OH absorption produced by proton exchange.

Guided-Wave Characteristics And Optical Damage In LiNb03 Waveguides

High power optical performances of Ti-indiffused and ion-exchanged waveguides were investigated and discussed. It was experimentally confirmed that Ti-indiffused waveguide suffered a serious optical damage at the output power density less than 0.1 mW/mm at A = 0.6328 pm. For x-propagating guided waves in y-cut crystal, the throughput decay time, by which we could characterize the dependences of optical damage, was revealed to be inversely propor-tional to square of initial guided power, P2, for TE modes, and to P3 for TM modes, and also confirmed to increase with an exponential function of wavelength λ. No optical damage was found for z-propagating guided waves. Proton-exchanged waveguides exhibited to have a good damage resistance. Their surface acoustic wave(SAW) performances, however, were found to be degraded; an IDTs insertion loss of 45 dB was measured, which was much larger than 13 - 14 dB available for Ti-indiffused waveguides. According to the experimental results of infrared absorption spectra, we speculate that the deterioration of SAW performances is attributed to the formation of a HNbO3 phase. A preliminary study using electron spin resonance(ESR) at 77 K provided us a good evidence of the close relation between impurities such as iron and free electrons in the crystal under UV light irradiation.

Evaluation Of Alternative Mo-Si Multilayer For Soft X-Ray Mirrors By Electron Microscopy And X-Ray Diffraction

For realizing high-reflection multilayer mirrors, Mo-Si multilayers of 60 layer pairs with layer thicknesses of dSi ≈ 7.3 nm and dMo - 4.0 nm are deposited by magnetron sputter-ing on super-polished Si (100) substrates with rms surface roughness of several tenth of a nm. A typical reflectance value obtained by synchrotron radiation reflectometer using p-polarization radiation was 36 % at an incident angle 10o and a wavelength of λ = 21.0 nm. The structure and crystalline nature of these multilayers have been investigated by X-ray diffraction both at small and wide diffraction angles, transmission electron microscopy for surface and cross-sectional views, and selected area electron diffraction. These results suggest that the Si layers are amorphous whereas the Mo layers are crystalline with [110] axis oriented normal to the substrate. The grain sizes of Mo layers have approximately of the similar size as the film thickness along the direction of the film depth and approxi-mately 10 nm along the film surface. The interfaces also show several tenth to one nm rms roughness probably due to interlayer diffusion or to duplication of the substrate surface roughness. Using the results investigated in this paper, a microscopic structure of Mo-Si multilayer mirror is proposed.

Fabrication and Focal Test of a Free-Standing Zone Plate in the VUV Region

Much effort has been put into developing X-ray microscopy in the wavelength region between 2.37 and 4.47 nm (absorption edges of oxygen and carbon, respectively), because of the high contrast of biological materials against water. In the longer wavelength region, however, relatively few efforts have been made. We have studied the feasibility of sorting out the importance of the development of X-ray microscopy in longer wavelength region, and point out possiblities of the utilization of VUV light, such as the use of the phosphor absorption edge [1,2].

Feasibility Study for the Observation of Biological Materials in VUV Wavelength Regions. Using Zone Plates Fabricated by Electron and Ion Beam Lithographies

In biological system, the important things is to find out what really we should know. There are so many phenomena spreading in wide scale in space (10−11 – 102m) and in time (10−13 – 107sec) in biological world. A purpose of biological science is to explain such various biological phenomena (or more appropriately biological function) in terms of more established concepts in physical science such as thermodynamics and/or conformation. It should be stressed that the observation of biological substances is not the goal of biology, but merely the start of the understanding of the complicated biological systems in various space and time scale as desired. However it will be very much helpful in the fundamental understanding of biological function. This is the reason why we require methods to enlarge or reduce sizes in space and in time.