• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.298-299
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• 2000

3차원 영상을 디스플레이하기 위한 반사형 광기록식 공간 광소자(Optically Addressed Spatial Light Modulator)를 연구하였다. 다시점 영상으로 표현되는 3차원 영상을 시분할 방식으로 디스플레이 하기 위해서는 고속의 프레임 구동이 가능한 디스플레이 소자가 있어야 하는데 본 연구에서는 Surface Stabilized Ferroelectric Liquid Crystal을 이용하여 그림 1과 같은 구조를 갖는 소자를 제작하였다.$^{(1)}$ 입력상이 입사되는 방향에 1.1 미리 미터 정도의 ITO 유리 기판이 있으며 투명 전극 다음에 약 2마이크론 정도의 비결정질 구조를 갖는 Si:H 감광층이 있다. 반사형 구조를 위해서 반사경으로 알루미늄 층을 10마이크론 X 10 마이크론 크기의 미소 패턴으로 화소화하였으며 강유전성 액정 결정을 Surface Stabilized화하기 위해서 배양막과 2 마이크론 이하의 Spacer를 두었다. 일반적인 액정 소자와 같이 다시 배양막과 유리 기판을 갖게 하였다. (중략)

• Current Optics and Photonics
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• v.5 no.2
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• pp.134-140
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• 2021

In this paper, I introduce a novel design method of a high performance nanophotonic beam deflector providing broadband operation, large active tunability, and signal efficiency, simultaneously. By combining thermo-optically tunable vanadium dioxide nano-ridges and a metallic mirror, reconfigurable local optical phase of reflected diffraction beams can be engineered in a desired manner over broad bandwidth. The active metagrating deflectors are systematically designed for tunable deflection of reflection beams according to the thermal phase-change of vanadium dioxide nano-ridges. Moreover, by multiplexing the phase-change supercells, a robust design of actively tunable beam splitter is also verified numerically. It is expected that the proposed intuitive and simple design method would contribute to development of next-generation optical interconnects and spatial light modulators with high performances. The author also envisions that this study would be fruitful for modern holographic displays and three-dimensional depth sensing technologies.

• Proceedings of the Korean Magnestics Society Conference
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• 2003.12a
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• pp.304-304
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• 2003

• Proceedings of the Optical Society of Korea Conference
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• 1991.06a
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• pp.35-40
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• 1991

In this paper, a new adaptive learning algorithm, Training by Adaptive Gain (TAG) for optical implementation of large-sized neural networks has been developed and its electro-optical implementation for 2-dimensional input and output neurons has been demostrated. The 4-dimensional global fixed interconnections and 2-dimensional adaptive gain-controls are implemented by multi-facet computer generated holograms and LCTV spatial light modulators, respectively. When the input signals pass through optical system to the output classifying layer, the TAG adaptive learning algorithm is implemented by a personal computer. The system classifies three 5$\times$5 input patterns correctly.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.281-284
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• 2002

We first review a real-time holographic recording technique called optical scanning holography (OSH) and discuss holographic reconstruction using spatial light modulators (SLMs). We then present how the overall system can be used for three-dimensional (3-D) holographic television (TV) system and address some of the issues encountered. Finally, we suggest some techniques to alleviate the issues encountered in such a 3-D holographic TV.

• Journal of Information Display
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• v.3 no.3
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• pp.12-16
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• 2002

We first review a real-time three-dimensional (3-D) holographic recording technique called optical scanning holography (OSH) and discuss holographic reconstruction using spatial light modulators (SLMs). We then present how the overall system can be used for 3-D holographic television (TV) display with a wide-angle view of a 3-D image, and address some of the issues encountered. Finally, we suggest some techniques to alleviate the issues encountered in such a 3-D holographic TV system.

• Electronics and Telecommunications Trends
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• v.34 no.2
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• pp.10-18
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• 2019

Since the introduction of CRT(Cathode Ray Tube) in the 1950s, display technologies have been developed continuously. Flat panel displays such as PDP(Plasma Display Panel) and LCD(Liquid Crystal Display) were commercialized in the late 1990s, and OLED(Organic Light Emitting Diodes) and Micro-LED(Micro-Light Emitting Diodes) are now being developed and are becoming widespread. In the future, we expect to develop ultra-realistic, flexible, embedded sensor displays. Ultra-realistic display can be applied to AR/VR(Augmented Reality/Virtual Reality) devices and spatial light modulators for holography. The sensor-embedded display can be applied to robots; electronic skin; and security devices, including iris recognition sensors, fingerprint recognition sensors, and tactile sensors. AR/VR technology must be developed to meet technical requirements such as viewing angle, resolution, and refresh rate. Holography requires optical modulation technology that can significantly improve resolution, viewing angle, and modulation method to enable wide-view and high-quality hologram stereoscopic images. For electronic skin, stable mass production technology, large-area arrays, and system integration technologies should be developed.

• ETRI Journal
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• v.41 no.1
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• pp.32-41
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• 2019

We propose a speckle reduction technique in electronic holographic display systems, where digital micro-mirror array devices are used as spatial light modulators. By adopting a programmable filtration in a general 4-f optic configuration, it is shown that the signal spectrum components in the frequency domain of a viewing-window-based holographic display system can be selectively filtered. Compared to the widely utilized single-sideband filtration techniques in electronic holographic display systems, our proposed programmable filtration can be utilized to effectively reduce the speckles in the reconstruction of point-cloud-based computer-generated holograms. Experimental results are presented to verify our proposed concept.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.911-916
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• 2003

Microactuator is frequently used in some optical or electrical applications such as light modulators and spatial scanner devices. When microactuator is implemented, it should be operated at accurate positions proportional to input voltage. Therefore in order to obtain rapid responses and reduced errors, a position control technique is used. In the paper, design procedure for the mems actuator and a typical PID controller is adapted to improve performance of microactuator as well. Also electrostatic force for the torsional microactuator is calculated via well-known Hornbeck's method.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.8
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• pp.1262-1269
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• 1989

For the efficient recognition of Korean characters, a modified ternary phase-only synthetic discriminanty function filter(MTPOF-SDF) is proposed. MTPOF-SDF can not only discriminate the true class patterns and the similar, symmetric, or patially included false ones but also recognize the diverse variations in true class patterns due to combinatorial form as the same ones. And scale and rotation-invariant recognition is achieved. To preserve the features of the characters, phase information should be used. And to contsrol phase information easily, ternary quantization of the phase is preferred. Also low resolution requirement is achieved for compatibility with low resulution devices such as spatial light modulators.