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Conference on Micromachining Technology For Micro-Optics and Nano-Optics V and Microfabrication Process Technology XII

作者： Hsu, Wei-Feng Su, Yuan-Hong Natl Taipei Univ Technol Dept Electroopt Engn 1Sec 3Chung-Hsiao E RdNTUT Box 4623 Taipei 106 Taiwan

ISBN: (纸本)9780819465757

We proposed a method, which is the first to our knowledge, to realize the phase-shift patterns of the near-field lithography in the optical far field. The key component of the optical fourier system was a phase-only diffractive optical element which generated a diffracted light field of a semi-phase-only complex-valued function. The achieved feature size was beyond the diffraction limit. The advantages of the proposed method included the capability to generate the complicated patterns, spatial parallelism, and low cost.

关键词： phase-shift lithography diffraction limit sub-wavelength features phase-only diffractive optical elements iterative fourier transform algorithm dummy area

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Optimization methods of tilted multi-focus Fresnel binary optical elements

Optimization methods of tilted multi-focus Fresnel binary op...

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Conference on Holography, Diffractive Optics and Applications II

作者： Ling, WF Chen, LS Suzhou Univ Inst Informat Opt Engn Jiangsu Peoples R China

ISBN: (纸本)0819455911

In the Fresnel condition, the design and optimization method of binary optical element with multi-focus has been investigated. A one-step optimizing algorithm of tilted multi-focus diffiractive optical element is presented by using a tilted image plane in the Fresnel approximation. Based on iterative fourier transform algorithm(IFTA), not only the higher diffraction efficiency, increased about four percent, but also the instability of distributing at the different focus,namely different tilted angle,are obviously improved by the modified simulated annealing algorithm(SA). Comparison on one-step and multi-step circle algorithm of optimizing multi-focus diffraction element shows both the faster speed and the higher diffraction efficiency for the one-step algorithm.

关键词： binary optics diffraction iterative fourier transform algorithm simulated annealing algorithm tilted multi-focus

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Multispectra method for error reduction of the quantized fourier modulus in the iterative fourier transform algorithms used for phase retrieval

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OPTICAL ENGINEERING 2004年第3期43卷 713-717页

作者： Yang, SY Takajo, H Kyushu Inst Technol Dept Elect Engn Kitakyushu Fukuoka 8048550 Japan

A multispectra method is proposed for the error reduction of the quantized fourier modulus in the iterative fourier transform. algorithms used for phase retrieval. The fourier modulus is usually obtained by measuring the fourier intensity with a digital device, thus the quantization error caused in the measurements of fourier intensity leads to the error of the reconstructed object when iterative fourier transform algorithms are used. The idea of the multispectra method uses several fourier intensity distributions for various measuring ranges to generate a fourier intensity distribution with low-quantization error. The error reduction of fourier intensity with the multispectra method connects to the improvement of the phase retrieval with the iterative fourier transform algorithms. Simulations are performed to demonstrate the effect of the multispectra method for phase retrieval with the iterative hybrid input-output algorithm. (C) 2004 Society of Photo-Optical Instrumentation Engineers.

关键词： iterative fourier transform algorithm phase retrieval fourier modulus fourier intensity quantization error reduction algorithm hybrid input-out algorithm

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iterative calculation of the quasi-bandlimited diffuser in two dimensions from restricted phase distributions

Iterative calculation of the quasi-bandlimited diffuser in t...

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19th Congress of the International-Commission-for-Optics

作者： Chhetri, BB Serikawa, S Yang, S Shimomura, T Kyushu Inst Technol Dept Elect Engn Elect Course Shimomura Lab Kitakyushu Fukuoka 8048550 Japan

ISBN: (纸本)0819445967

We present a performance comparison of various initial phase distributions that provide successful iterative calculation of two-dimensional quasi-bandlimited diffusers for holographic use. Phase filtering concept is introduced to make previously unsuitable phase distribution suitable. Phase distributions obtained from the superposition of the one dimensional quasi-bandlimited diffuser, binary phase difference diffuser, and filtered restricted phase pseudorandom diffuser introduced in this article are considered.

关键词： quasi-bandlimited diffuser phase ambiguity iterative fourier transform algorithm holography speckle reduction

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Binary phase difference diffuser: Design and application in digital holography

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OPTICAL ENGINEERING 2002年第2期41卷 319-327页

作者： Chhetri, BB Serikawa, S Yang, SY Shimomura, T Kyushu Inst Technol Dept Elect Engn Elect Course Tobata Ku Kitakyushu Fukuoka 8048550 Japan

Design of a simple diffuser, in which the absolute value of the phase difference between the diffuser's adjacent samples is constant, is considered. A condition is imposed in the design so that the diffuser is suitable for use with the iterative method based on the iterative fourier transform algorithm for calculating a two-dimensional complex amplitude function that possesses a bandlimited and smooth spectrum. A method for effectively designing this diffuser is proposed, and its application in the field of digital holography is presented. (C) 2002 Society of Photo-Optical Instrumentation Engineers.

关键词： digital holography binary phase difference diffuser bandlimited smooth spectrum phase ambiguity object-dependent diffuser iterative fourier transform algorithm

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Optimal design of boundary-modulated diffractive optical elements for general beam shaping

Optimal design of boundary-modulated diffractive optical ele...

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Conference on Practical Holography XVI and Holographic Materials VIII

作者： Kim, H Yang, B Park, J Lee, B Seoul Natl Univ Sch Elect Engn Natl Res Lab Holog Technol Kwanak Gu Seoul 151744 South Korea

ISBN: (纸本)0819443999

The inherent feature of the coherent optics is the speckle phenomena. To reduce the spiral speckles in the diffraction image generated by the diffractive optical element, we designed the boundary modulated diffractive optical element. The spiral speckles can be removed by introducing an appropriate smooth initial phase to the image plane and conserving the smoothness of it during the iteration process of the iterative fourier transform algorithm. To conserve the smoothness of the phase on the image plane, the aperture shape of the diffractive optical element is modified optimally. The diffractive optical element with deformed aperture decreases the transmission efficiency. To increase the transmission efficiency, the initial phase distribution of the image plane is optimized by use of the genetic algorithm.

关键词： beam shaping iterative fourier transform algorithm diffractive optical element spiral speckle genetic algorithm

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Phase retrieval microscope based on photon image detection

Phase retrieval microscope based on photon image detection

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8th Microoptic Conference (MOC 01)

作者： Nakashima, Y Hattori, M Komatsu, S Waseda Univ Sch Sci & Engn Dept Appl Phys Tokyo 1698555 Japan Waseda Univ Adv Res Ctr Sci & Engn Shinju Ku Tokyo 1698555 Japan Waseda Univ Mat Res Lab Biosci & Photon Shinju Ku Tokyo 1698555 Japan

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, a photon-imaging detector was adopted to detect higher order diffraction spots of a very weak phase grating. The phase retrieval was accomplished fairly well experimentally 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 satisfactory accuracy and sensitivity. A newly introduced procedure for measuring the entire diffraction pattern with single photon-imaging detector is also described.

关键词： phase retrieval iterative fourier transform algorithm Fraunhofer diffraction

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Phase retrieval microscope based on photon image detection

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JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 2002年第7B期41卷 4809-4812页

关键词： phase retrieval iterative fourier transform algorithm Fraunhofer diffraction

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iterative stepwise binarization of digital amplitude holograms with added energy to the signal window

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OPTICAL ENGINEERING 2001年第12期40卷 2718-2725页

作者： Chhetri, BB Yang, SY Shimomura, T Kyushu Inst Technol Dept Elect Engn Elect Course Tobata Ku Kitakyushu Fukuoka 8048550 Japan

We propose a method for optimizing the process of iteratively binarizing digital amplitude holograms by utilizing the effect of adding energy to the reconstructed signal window from the hologram. For this purpose, we introduce a parameter called the energy factor and show that the performance of the iterative binarization process can be greatly enhanced if the value of the energy factor is properly chosen. Finally, we show that the optimal values of this energy factor can be estimated with an analytical function for different computational costs. (C) 2001 Society of Photo-Optical Instrumentation Engineers.

关键词： fourier holography digital amplitude hologram iterative fourier transform algorithm iterative stepwise binarization hologram domain object domain constraints energy factor

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An efficiency optimization approach for two-wavelength diffractive optical elements

An efficiency optimization approach for two-wavelength diffr...

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Advanced Photonic Sensors and Applications II Conference

作者： Hsu, WF Ni, CT Natl Taipei Univ Tehcnol Dept Photon Taipei Taiwan

ISBN: (纸本)0819443263

In this paper, we present a design of a phase-only diffractive optical element (DOE), which is capable of producing two distinct diffractive patterns for two wavelengths with high and equal diffraction efficiencies. The DOE is constructed by two one-sided surface profiles that are stacked together and in contact with a thin focusing lens. One is designed for a wavelength of the incident light to generate a pattern on the back focal plane, and the other is for the second wavelength to generate a different diffractive pattern without affecting the first pattern. The second profile simply provides a multiple of 2-pi phase delay for the first wavelength and thus has no effect on the first pattern. In the proposed algorithm, the iterative fourier transform algorithm with the stepwise quantization method is modified to calculate the two phase profiles simultaneously in the iterations. High and equal diffraction efficiency (74.5%) for the two wavelengths was achieved with 2 phase profiles of 4 uniform phase levels. In addition, a method of multiple bounding controls was proposed to increase the SNR in the regions of interest so as to improve the chromatic performance of the double wavelength design. Different SNR's (5.7 dB and 1.7 dB) were achieved at signal and noise regions.

关键词： diffractive optical elements wavelength separation two-wavelength operation iterative fourier transform algorithm multiple bounding control diffractive efficiency signal-to-noise ratio signal variation uniformity

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