2001 Fiscal Year Final Research Report Summary
Phase Retrieval Microscope Based on Photon Counting Image Detection
| Project/Area Number |
10450029
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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 | Waseda University |
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Principal Investigator |
KOMATSU Shinichi Waseda University, School of Science and Engineering, Professor, 理工学部, 教授 (00087446)
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| Co-Investigator(Kenkyū-buntansha) |
HATTORI Masayuki Waseda University, School of Science and Engineering, Assistant, 理工学部, 助手 (20308208)
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| Project Period (FY) |
1998 – 2001
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| Keywords | phase recovery / photon counting / visualization / inverse problem / lightwave sensing / photon imaging / optical measurements / accurate measurements |
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| Research Abstract |
The accuracy and sensitivity of the phase retrieval from a Fraunhofer diffraction pattern greatly depend on the dynamic range of the measured Fraunhofer diffraction pattern. In this study, the photon-imaging detector was adopted to detect higher order diffraction spots of a very weak phase grating. The phase retrieval was accomplished experimentally fairly well from the Fraunhofer diffraction intensity distribution data including up to the third order diffraction spots to which the iterative Fourier transform algorithms were applied. The object phase distribution was retrieved with fairly high accuracy and sensitivity. A newly introduced procedure for measuring the entire diffraction pattern with single photon-imaging detector is also described.
The application of the ML-EM (maximum likelihood-expectation maximization) method to the processing of images of extremely low intensity, which is detectable only with a photon counting camera, is also examined. The influence of the photon noise is also quantitatively examined. It is experimentally shown that the ML-EM produces better restoration than the Wiener filter in the extremely low intensity region where the maximal number of photons per pixel is less than about one hundred.
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