2002 Fiscal Year Final Research Report Summary
3-dimensional measurements by infrared phase-shifting digital holography
| Project/Area Number |
13555016
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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 | 展開研究 |
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| Research Field |
Applied optics/Quantum optical engineering
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| Research Institution | RIKEN(The institute of physical and chemical research) |
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Principal Investigator |
KATO Jun-ichi RIKEN, Nanophotonics Lab., Senior Research Scientist, ナノフォトニクス研究室, 先任研究員 (70177450)
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| Co-Investigator(Kenkyū-buntansha) |
YAMAGUCHI Ichirou Gunma University, Department of Electronic Engineering, Professor, 工学部, 教授 (70087443)
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| Project Period (FY) |
2001 – 2002
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| Keywords | holography / image processing / interferometry / infrared imaging / microscopy |
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| Research Abstract |
The purpose of this research is to develop a new technique that enables to form good 3-dimensional image in the infrared region where performances of imaging components are not so good as in the visible region and to realize interferometry and microscopy that make use of phase reconstruction. We first demonstrated reconstruction of colored images by using a 3-wavelength laser (He-Cd laser, 636 nm,537 nm, and 441 nm). The amount of phase shift was correct at the central wavelength but contains errors at the other wavelengths. We conducted computer simulation for evaluating the effect that proved not to be serious. We also compared two algorithms of reconstruction and clarified the conditions for choice. The phase shifting error could be removed by an achromatic phase shifter to provide better images.
In infrared region we employed a laser of wavelength 830 nm and output power of 30 mW to reconstruct a point, diffusely reflecting objects, and phase objects. By means of phase reconstruction we could analyze surface shape of mirrors and liquid surfaces quantitatively. For diffusely reflecting surfaces, we took the difference of the reconstructed phases before and after tilt of the object illumination or object deformation to measure surface shape and displacement with resolutions of 10 micrometers and 10 nm, respectively. We also could extend the object size by employing an imaging setup.
In conclusion, we can reconstruct satisfactory 3-dimensional images by using the phase-shifting digital holography in the infrared region and will be able to attain 3-dimensional measurements on Silicon crystals and biological objects which are opaque in the visible region.
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