2002 Fiscal Year Final Research Report Summary
Spatial coherence synthesis imaging
| Project/Area Number |
13450028
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied optics/Quantum optical engineering
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| Research Institution | Tokyo University of Agriculture & Technology |
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Principal Investigator |
TAKAKI Yasuhiro Tokyo University of Agriculture & Technology, Department of Electric and Electronic Engineering, Associate Professor, 工学部, 助教授 (50236189)
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| Co-Investigator(Kenkyū-buntansha) |
KUROKAWA Takashi Tokyo University of Agriculture & Technology, Department of Electric and Electronic Engineering, Professor, 工学部, 教授 (40302913)
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| Project Period (FY) |
2001 – 2002
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| Keywords | Spatial coherence / Optimization / Fourier transform / Nano-structure / Vector diffraction / Diffractivc optical element |
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| Research Abstract |
The theory of spatial coherence synthesis imaging and the fabrication technique of diffractive optical elements having nano-structure are studied.
The Fourier iterative algorithm was developed for the design of mask patterns which generate super-resolution patterns. The Fourier iterative algorithm was applied between the pupil plane and the image plane. The contrast of the super-resolution pattern became sufficiently high with about 100 iterations.
There is the tradeoff between the arbitrary pattern generation and the high contrast image generation. In order to overcome this problem, the line width of the super-resolution patterns is limited to λ/4 NA. This enables to limit the spatial frequency components of the super-resolution patterns around the highest spatial frequencies so that the contrast becomes higher.
The pattern contrast was more improved by limiting the pattern orientations to one direction. The two-dimensional line patterns are divided into horizontal lines and horizontal lines. The optimization is performed independently for both directional lines. Two super-resolution images, which consist of lines having different directions, are double-exposed to generate arbitrary two-dimensional super-resolution patterns.
The optical characteristics of optical elements having nano-structure can be calculated by use of the vector diffraction theories, not by the conventional scalar diffraction theories. We introduced rigorous coupled-wave analysis for the vector diffraction calculation. We examined the optical characteristics with this theory and determined the spatial period and the aspect ratio of the optical elements.
A new nano-structure fabrication technique was proposed, which uses several spatial shifts of a one-dimensional fine pattern to produce a much finer pattern. This technique offers the higher throughput and the higher pattern accuracy than the conventional emboss technique which is now used for the mass production.
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