Jiwoon Yeom
Seoul National University
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Featured researches published by Jiwoon Yeom.
Optics Letters | 2014
Keehoon Hong; Jiwoon Yeom; Changwon Jang; Jisoo Hong; Byoungho Lee
A novel system of optical see-through augmented reality (AR) is proposed by making use of a holographic optical element (HOE) with full-color and lens-array functions. The full-color lens-array HOE provides see-through property with three-dimensional (3D) virtual images, for it functions as a conventional lens array only for Bragg-matched lights. An HOE recording setup was built, and it recorded a 30 mm × 60 mm sized full-color lens-array HOE by using the techniques of spatial multiplexing for large-area recording and wavelength multiplexing for full-color imaging. The experimental results confirm that the suggested full-color lens-array HOE can provide the full-color 3D virtual images in the optical see-through AR system.
Optics Express | 2012
Young-Min Kim; Keehoon Hong; Jiwoon Yeom; Jisoo Hong; Jae-Hyun Jung; Yong Wook Lee; Jae-Hyeung Park; Byoungho Lee
In a typical auto-stereoscopic three-dimensional display, the parallax barrier or lenticular lens is located in front of the display device. However, in a projection-type auto-stereoscopic display, such optical components make it difficult to display elemental images on the screen or to reconstruct a three-dimensional image, even though a projection-type display has many advantages. Therefore, it is necessary to use a rear projection technique in a projection-type auto-stereoscopic display, despite the fact that this is an inefficient use of space. We propose here a frontal projection-type auto-stereoscopic display by using a polarizer and a quarter-wave retarding film. Since the proposed method uses a frontal projection scheme and passive polarizing components, it has the advantage of being both space saving and cost effective. This is the first report that describes a frontal projection-type auto-stereoscopic display based on a parallax barrier and integral imaging by using a projector. Experimental results that support the proposed method are provided.
Journal of information display | 2014
Soon-gi Park; Jiwoon Yeom; Youngmo Jeong; Ni Chen; Jong-Young Hong; Byoungho Lee
In this review paper, the recent progress of 3D applications using integral imaging is introduced. Thanks to the progress of the flat panel displays, the quality of the 3D displays has also improved, resulting in the opening of more applications of the 3D display. The previous studies on integral imaging emphasized the improvement of the viewing quality of the integral imaging system, but the emergence of new technologies requires more than the replacement of the current 2D displays. New applications of the integral imaging method, such as displays with augmented reality, 3D information capturing, real-time processing, the projection-type method, and the integral floating method, and their recent research trends, are introduced.
Applied Optics | 2016
Changwon Jang; Chang-Kun Lee; Jinsoo Jeong; Gang Li; Seung-Jae Lee; Jiwoon Yeom; Keehoon Hong; Byoungho Lee
The principles and characteristics of see-through 3D displays are presented. We especially focus on the integral-imaging display system using a holographic optical element (IDHOE), which is able to display 3D images and satisfy the see-through property at the same time. The technique has the advantage of the high transparency and capability of displaying autostereoscopic 3D images. We have analyzed optical properties of IDHOE for both recording and displaying stages. Furthermore, various studies of new applications and system improvements for IDHOE are introduced. Thanks to the characteristics of holographic volume grating, it is possible to implement a full-color lens-array holographic optical element and conjugated reconstruction as well as 2D/3D convertible IDHOE. Studies on the improvements of viewing characteristics including a viewing angle, fill factor, and resolution are also presented. Lastly, essential issues and their possible solutions are discussed as future work.
Nature Communications | 2015
Hansik Yun; S. Lee; Keehoon Hong; Jiwoon Yeom; Byoungho Lee
Despite steady technological progress, displays are still subject to inherent limitations in resolution improvement and pixel miniaturization because a series of colours is generally expressed by a combination of at least three primary colour pixels. Here we propose a structure comprising a metal cavity and a nanoaperture, which we refer to as a cavity-aperture, to simultaneously control the colour and intensity of transmitted light in a single pixel. The metal cavity constructs plasmonic standing waves to organize the spatial distribution of amplitudes according to wavelength, and the nanoaperture permits light with a specific wavelength and amplitude to pass through it, depending on the nanoaperatures relative position in the cavity and the polarization state of the incident light. Therefore, the cavity-aperture has the potential to function as a dynamic colour pixel. This design method may be helpful in developing various photonic devices, such as micro-imaging systems and multiplexed sensors.
Optics Express | 2011
Jae-Hyun Jung; Jiwoon Yeom; Jisoo Hong; Keehoon Hong; Sung-Wook Min; Byoungho Lee
In three-dimensional television (3D TV) broadcasting, we find the effect of fundamental depth resolution and the cardboard effect to the perceived depth resolution on multi-view display is important. The observer distance and the specification of multi-view display quantize the expressible depth range, which affect the perception of depth resolution of the observer. In addition, the multi-view 3D TV needs the view synthesis process using depth image-based rendering which induces the cardboard effect from the relation among the stereo pickup, the multi-view synthesis and the multi-view display. In this paper, we analyze the fundamental depth resolution and the cardboard effect from the synthesis process in the multi-view 3D TV broadcasting. After the analysis, the numerical comparison and subjective tests with 20 participants are performed to find the effect of fundamental depth resolution and the cardboard effect to the perceived depth resolution.
Optics Express | 2014
Keehoon Hong; Jiwoon Yeom; Changwon Jang; Gang Li; Jisoo Hong; Byoungho Lee
Two-dimensional (2D) and three-dimensional (3D) transparent screens can be created using lens-array holographic optical elements (HOEs). Lens-array HOEs can be used to perform 2D and 3D imaging for Bragg matched images while maintaining the transparent properties of the images in the background scenes. 2D or 3D imaging on the proposed screen is determined by the relative size of an elemental-lens on the lens-array to a pixel on the projected image. The 2D and 3D displays on the lens-array HOEs are implemented by the diffusion of light on each elemental-lens and by taking advantage of reflection-type integral imaging, respectively. We constructed an HOE recording setup and recorded two lens-array HOEs having different optical specifications, permitting them to function as 2D and 3D transparent screens. Experiments regarding 2D and 3D imaging on the proposed transparent screens are carried out and the viewing characteristics in both cases are discussed. The experimental results show that the proposed screens are capable of providing 2D and 3D images properly while satisfying the see-through properties.
Optics Express | 2013
Keehoon Hong; Soon-gi Park; Jiwoon Yeom; Jonghyun Kim; Ni Chen; Kyungsuk Pyun; Chil-Sung Choi; Sun-Il Kim; Jungkwuen An; Hong-Seok Lee; U-in Chung; Byoungho Lee
We propose a hogel overlapping method for the holographic printer to enhance the lateral resolution of holographic stereograms. The hogel size is directly related to the lateral resolution of the holographic stereogram. Our analysis by computer simulation shows that there is a limit to decreasing the hogel size while printing holographic stereograms. Instead of reducing the size of hogel, the lateral resolution of holographic stereograms can be enhanced by printing overlapped hogels, which makes it possible to take advantage of multiplexing property of the volume hologram. We built a holographic printer, and recorded two holographic stereograms using the conventional and proposed overlapping methods. The images and movies of the holographic stereograms experimentally captured were compared between the conventional and proposed methods. The experimental results confirm that the proposed hogel overlapping method improves the lateral resolution of holographic stereograms compared to the conventional holographic printing method.
Optics Express | 2011
Ni Chen; Jiwoon Yeom; Jae-Hyun Jung; Jae-Hyeung Park; Byoungho Lee
We compare the resolution of the hologram reconstruction synthesis methods based on integral imaging using rectangular and hexagonal lens arrays. By using a hexagonal lens array instead of conventional rectangular lens array, the three-dimensional objects are sampled with hexagonal grids. Due to more efficient sampling of the hexagonal grid, the resolution of the reconstructed object is higher compared with the case of using rectangular lens array. We analyze the resolution enhancement of the hologram reconstruction quantitatively and verify it experimentally.
Optics Express | 2014
Changwon Jang; Keehoon Hong; Jiwoon Yeom; Byoungho Lee
We report on the development of a high-resolution see-through integral imaging system with a resolution and fill factor-enhanced lens-array holographic optical element (HOE). We propose a procedure for fabricating of a lens pitch controllable lens-array HOE. By controlling the recording plane and performing repetitive recordings process, the lens pitch of the lens-array HOE could be substantially reduced, with a high fill factor and the same numerical aperture compared to the reference lens-array. We demonstrated the feasibility by fabricating a lens-array HOE with a 500 micrometer pitch. Since the pixel pitch of the projected image can be easily controlled in projection type integral imaging, the small lens pitch enhances the quality of the displayed 3D image very effectively. The enhancement of visibility of the 3D images is verified in experimental results.