• Journal of the Optical Society of Korea
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• v.16 no.3
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• pp.256-262
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• 2012

We derive the point-spread function of the reconstructed image from a point-source complex hologram, which includes phase error caused by polarization components, in the longitudinal direction of the point-spread function and analyze the effect of the error sources of polarization components having influence on image reconstruction of a point-source complex hologram in incoherent triangular holography.

• Journal of the Optical Society of Korea
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• v.18 no.2
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• pp.146-150
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• 2014

We propose an experimental holographic imaging scheme combining compressive sensing (CS) theory with digital holography in phase-shifting conditions. We use the Mach-Zehnder interferometer for hologram formation, and apply the compressive sensing (CS) approach to the holography acquisition process. Through projecting the hologram pattern into a digital micro-mirror device (DMD), finally we will acquire the compressive sensing measurements using a photodiode. After receiving the data of two holograms via conventional communication channel, we reconstruct the original object using certain signal recovery algorithms of CS theory and hologram reconstruction techniques, which demonstrated the feasibility of the proposed method.

• Korean Journal of Optics and Photonics
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• v.14 no.3
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• pp.244-248
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• 2003

When confocal lenses are applied to a digital holography system, the interference pattern of a larger object size can be recorded on CCD. The angle of incoming light to the CCD can be reduced by the ratio of the two focal lengths of confocal lenses. The recordable spatial frequency is limited by the unit cell size of the CCD. Therefore the spatial frequency of interference on the CCD is lowered by reduction of the incoming light angle. By using confocal lenses , another merit can be achieved that the area of the zero order diffraction is reduced by the square of the ratio of two focal lengths at the numerical reconstruction.

• ETRI Journal
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• v.41 no.1
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• pp.23-31
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• 2019

Since the late 20th century, there has been rapid development in the display industry. Only 30 years ago, we used big cathode ray tube displays with poor resolution, but now most people use televisions or smartphones with very high-quality displays. People now want images that are more realistic, beyond the two-dimensional images that exist on the flat screen, and digital holography-one of the next-generation displaysis expected to meet that need. The most important parameter that determines the performance of a digital hologram is the pixel pitch. The smaller the pixel pitch, the higher the level of hologram implementation possible. In this study, we fabricated the world-smallest $3-{\mu}m$-pixel-pitch holographic backplane based on the spatial light modulator technology. This panel could display images with a viewing angle of more than $10^{\circ}$. Furthermore, a comparative study was conducted on the fabrication processes and the corresponding holographic results from the large to the small pixel-pitch panels.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1553-1560
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• 2006

The idea of displaying hologram electronically has been existed since mid $1960^{th}$. But it is still in the beginning stage due to the lacks of proper means of displaying and recording, which will bear the large amount of data contained in the hologram though holographic video and digital holography have demonstrated the possibility of displaying and photographing hologram electronically. It is expected that holography based 3 dimensional imaging system will be introduced much later than that on multiview 3 dimensional imaging methods which are being developed to generate more realistic and natural image than high definition plane images.

• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.2
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• pp.141-149
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• 2015

In the fabrication of electronic circuits used in electronic products, molybdenum thin films are deposited on semiconductors to prevent oxidation. During the deposition, the presence of a particle or dust at the interface between the thin film and substrate causes the decrease of adhesion, performance, and life cycle. In this study, a damage measurement targeting two kinds of glass substrate, with and without particles, was performed in order to measure the change in the molybdenum thin film deposition area in the presence of a particle. Clean and dirty molybdenum thin film specimens were fabricated and directly deposited on a substrate using the sputtering method, and a reflection-type digital holographic interferometer was configured for measuring the damage. Reflection-type digital holography has several advantages; e.g., the configuration of the interferometer is simple, the measurement range can be varied depending on the magnification of a microscopic lens, and the measuring time is short. The results confirm that reflection-type digital holography is useful for the measurement of the damage and defects of thin films.

• Journal of the Korean Society of Visualization
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• v.10 no.3
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• pp.11-15
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• 2012

Inertial migration phenomena of phytoplankton in pipe flows were investigated using a digital holography technique. As the Reynolds number increases, the microorganisms suspended in a pipe flow are focused at a certain radial position which is called equilibrium position or pinch point. In this study, the effects of the size of microorganism and Reynolds number in the range of 1 < Re < 78 on the inertial migration were investigated and the results are compared with those for solid particles under similar experimental conditions. As a result, the equilibrium position for the elastic microorganisms is not so distinct, compared to the solid particles. This results from deformation of elastic body shape caused by shear-gradient of surrounding flow.

• Korean Journal of Optics and Photonics
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• v.25 no.2
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• pp.85-89
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• 2014

In this paper, we present a speckle-free digital hologram with conversion to an off-axis horizontal-parallax-only (HPO) hologram. First, we record the speckle-free hologram using optical scanning holography. Second, we digitally convert the full-parallax hologram to a horizontal-parallax-only hologram. Third, we convert the horizontal-parallax-only hologram to an off-axis hologram. Finally, we show that the off-axis HPO hologram can be numerically reconstructed in space.

• 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 Korean Society of Broadcast Engineers Conference
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• 2020.07a
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• pp.561-562
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• 2020

기하학적 위상렌즈를 활용한 광시야각 홀로그램 합성을 위한 시스템을 제안하고 설계하여 제작하였다. 광시야각 홀로그램은 실시간 홀로그램 영상을 녹화하는 과정에서 동시에 물체의 다른 파면을 기록할 수 있기 때문에 물체의 3 차원 정보를 일련의 알고리즘을 통해 데이터화 시키는 과정을 가능하게 한다. 본 논문에서는 기하학적 위상렌즈와 편광 이미지 센서를 결합해 비간섭성 광원의 홀로그램을 기록할 수 있는 자가 간섭 디지털 홀로그래피 시스템을 이용하여 관찰하고자 하는 물체의 파면을 다각도에서 기록하는 광시야각 홀로그램 촬영 시스템을 개발하였다.