The neutron supermirror is an important neutron optical device that can significantly improve the efficiency of neutron transport in neutron guides and has been widely used in research neutron sources.Three types of a...The neutron supermirror is an important neutron optical device that can significantly improve the efficiency of neutron transport in neutron guides and has been widely used in research neutron sources.Three types of algorithms,including approximately ten algorithms,have been developed for designing high-efficiency supermirror structures.In addition to its applications in neutron guides,in recent years,the use of neutron supermirrors in neutronfocusing mirrors has been proposed to advance the development of neutron scattering and neutron imaging instruments,especially those at compact neutron sources.In this new application scenario,the performance of supermirrors strongly affects the instrument performance;therefore,a careful evaluation of the design algorithms is needed.In this study,we examine two issues:the effect of nonuniform film thickness distribution on a curved substrate and the effect of the specific neutron intensity distribution on the performance of neutron supermirrors designed using existing algorithms.The effect of film thickness nonuniformity is found to be relatively insignificant,whereas the effect of the neutron intensity distribution over Q(where Q is the magnitude of the scattering vector of incident neutrons)is considerable.Selection diagrams that show the best design algorithm under different conditions are obtained from these results.When the intensity distribution is not considered,empirical algorithms can obtain the highest average reflectivity,whereas discrete algorithms perform best when the intensity distribution is taken into account.The reasons for the differences in performance between algorithms are also discussed.These findings provide a reference for selecting design algorithms for supermirrors for use in neutron optical devices with unique geometries and can be very helpful for improving the performance of focusing supermirror-based instruments.展开更多
The design,fabrication and characterization of the X-ray supermirrors are discussed in this paper.Using the local optimization method of simplex algorithm and the global one of simulated annealing algorithm with diffe...The design,fabrication and characterization of the X-ray supermirrors are discussed in this paper.Using the local optimization method of simplex algorithm and the global one of simulated annealing algorithm with different initial multilayer structures,we designed the broad angular band supermirrors with different grazing incidence angle intervals at the energy of 8.0 keV(the Kαline of Cu)and the broad energetic band supermirrors with different energy intervals at fixed grazing incidence angles.The fabricating techniques for depositing non-periodic multilayers are also studied.The W/C and W/Si supermirrors are deposited on silicon substrates and characterized by a high resolution X-ray D1 diffractometer from Bede Company,UK.Choosing the interface roughness and the densities of the materials as independent variables,some measured reflectivity curves are fitted using the Debye-Waller factor with interface roughness.The experimental results show that the optical performances of the fabricated supermirrors are in agreement with the designed ones.展开更多
To develop beam splitters for soft X-ray laser Michelson interferometer at 13.9 nm, Mo/Si multilayers of 100 nm thickness deposited on both sides of silicon nitride were fabricated by using DC magnetron sputtering. In...To develop beam splitters for soft X-ray laser Michelson interferometer at 13.9 nm, Mo/Si multilayers of 100 nm thickness deposited on both sides of silicon nitride were fabricated by using DC magnetron sputtering. Initial evaluation of their reflectivity and transmission showed that reflectivity and transmission were above 10% and 25%. The broadband analyzers have been designed, fabricated and characterized for 13～20 nm polarization measurements. The measured results are in good agreement with the design. The supermirrors with different angular intervals at 0.154 nm have been designed, fabricated and characterized.展开更多
In EUV and X- ray regions, multilayer mirrors are the essential and necessary optics elements. The good prospects of the EUV and X- rays for next generation lithography system, microscopy in the “water windows”, ast...In EUV and X- ray regions, multilayer mirrors are the essential and necessary optics elements. The good prospects of the EUV and X- rays for next generation lithography system, microscopy in the “water windows”, astro- nomical telescope, spectroscopy, plasma diagnostics, and X- ray laser have impelled the development of multilayer optics. The paper introduces the recent results of the multilayer optics elements in Tongji University, including beam splitters, broadband/angular polarizers, supermirrors and high- reflectance mirrors. The product of reflectivity and transmissivity is above 4% for the Mo/Si multilayer beam splitter. Over the 15￣17 nm wavelength range, the s- re- flectivity of the non- periodic Mo/Si broadband multilayer polarizers is reasonably constant, as high as 36.6%, and the degree of polarization is more than 97.8%. At the fixed energy of 8 keV (Cu Kαline), the W/Si supermirror has the reflectivity of above 30% in the angle range of 0.4°￣0.85°, and a W/B4C supermirror has the reflectivity of about 20% in the angle range of 0.9°￣1.2°, and the reflectivity of W/C supermirror working in the grazing incident angle range of 0.9°￣1.2°is about 20%. The experimental results of some high- reflectance mirrors in our lab are also pre- sented, such as Mo/Si, Mo/Y, Cr/C, La/B4C, Si/C and Si/SiC. The reflectivity of Mo/Si multilayer is as high as 61.1% at wavelength of 13.4 nm.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 12027810 and 11322548)
文摘The neutron supermirror is an important neutron optical device that can significantly improve the efficiency of neutron transport in neutron guides and has been widely used in research neutron sources.Three types of algorithms,including approximately ten algorithms,have been developed for designing high-efficiency supermirror structures.In addition to its applications in neutron guides,in recent years,the use of neutron supermirrors in neutronfocusing mirrors has been proposed to advance the development of neutron scattering and neutron imaging instruments,especially those at compact neutron sources.In this new application scenario,the performance of supermirrors strongly affects the instrument performance;therefore,a careful evaluation of the design algorithms is needed.In this study,we examine two issues:the effect of nonuniform film thickness distribution on a curved substrate and the effect of the specific neutron intensity distribution on the performance of neutron supermirrors designed using existing algorithms.The effect of film thickness nonuniformity is found to be relatively insignificant,whereas the effect of the neutron intensity distribution over Q(where Q is the magnitude of the scattering vector of incident neutrons)is considerable.Selection diagrams that show the best design algorithm under different conditions are obtained from these results.When the intensity distribution is not considered,empirical algorithms can obtain the highest average reflectivity,whereas discrete algorithms perform best when the intensity distribution is taken into account.The reasons for the differences in performance between algorithms are also discussed.These findings provide a reference for selecting design algorithms for supermirrors for use in neutron optical devices with unique geometries and can be very helpful for improving the performance of focusing supermirror-based instruments.
基金supported by the National Natural Science Foundation of China(Grant No.60178023)the Shanghai Development Foundation of Science and Technology(Grant No.0352nm090).
文摘The design,fabrication and characterization of the X-ray supermirrors are discussed in this paper.Using the local optimization method of simplex algorithm and the global one of simulated annealing algorithm with different initial multilayer structures,we designed the broad angular band supermirrors with different grazing incidence angle intervals at the energy of 8.0 keV(the Kαline of Cu)and the broad energetic band supermirrors with different energy intervals at fixed grazing incidence angles.The fabricating techniques for depositing non-periodic multilayers are also studied.The W/C and W/Si supermirrors are deposited on silicon substrates and characterized by a high resolution X-ray D1 diffractometer from Bede Company,UK.Choosing the interface roughness and the densities of the materials as independent variables,some measured reflectivity curves are fitted using the Debye-Waller factor with interface roughness.The experimental results show that the optical performances of the fabricated supermirrors are in agreement with the designed ones.
文摘To develop beam splitters for soft X-ray laser Michelson interferometer at 13.9 nm, Mo/Si multilayers of 100 nm thickness deposited on both sides of silicon nitride were fabricated by using DC magnetron sputtering. Initial evaluation of their reflectivity and transmission showed that reflectivity and transmission were above 10% and 25%. The broadband analyzers have been designed, fabricated and characterized for 13～20 nm polarization measurements. The measured results are in good agreement with the design. The supermirrors with different angular intervals at 0.154 nm have been designed, fabricated and characterized.
基金the National Natural Science Foundation of China under the contract numbers 60178021,60378021 , 10435050 National High Technology Research and Development“863”Program of China.(No.3)
文摘In EUV and X- ray regions, multilayer mirrors are the essential and necessary optics elements. The good prospects of the EUV and X- rays for next generation lithography system, microscopy in the “water windows”, astro- nomical telescope, spectroscopy, plasma diagnostics, and X- ray laser have impelled the development of multilayer optics. The paper introduces the recent results of the multilayer optics elements in Tongji University, including beam splitters, broadband/angular polarizers, supermirrors and high- reflectance mirrors. The product of reflectivity and transmissivity is above 4% for the Mo/Si multilayer beam splitter. Over the 15￣17 nm wavelength range, the s- re- flectivity of the non- periodic Mo/Si broadband multilayer polarizers is reasonably constant, as high as 36.6%, and the degree of polarization is more than 97.8%. At the fixed energy of 8 keV (Cu Kαline), the W/Si supermirror has the reflectivity of above 30% in the angle range of 0.4°￣0.85°, and a W/B4C supermirror has the reflectivity of about 20% in the angle range of 0.9°￣1.2°, and the reflectivity of W/C supermirror working in the grazing incident angle range of 0.9°￣1.2°is about 20%. The experimental results of some high- reflectance mirrors in our lab are also pre- sented, such as Mo/Si, Mo/Y, Cr/C, La/B4C, Si/C and Si/SiC. The reflectivity of Mo/Si multilayer is as high as 61.1% at wavelength of 13.4 nm.
