Browsing by Author "Hsieh, Po-Yuan"

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A 2D/3D Hybrid Integral Imaging Display by Using Fast Switchable Hexagonal Liquid Crystal Lens Array
(2017-01-01)
Lee, Hsin-Hsueh
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Huang, Ping-Ju
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Wu, Jui-Yi
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Hsieh, Po-Yuan
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Huang, Yi-Pai
The paper proposes a new display which could switch 2D and 3D images on a monitor, and we call it as Hybrid Display. In 3D display technologies, the reduction of image resolution is still an important issue. The more angle information offer to the observer, the less spatial resolution would offer to image resolution because of the fixed panel resolution. Take it for example, in the integral photography system, the part of image without depth, like background, will reduce its resolution by transform from 2D to 3D image. Therefore, we proposed a method by using liquid crystal component to quickly switch the 2D image and 3D image. Meanwhile, the 2D image is set as a background to compensate the resolution.. In the experiment, hexagonal liquid crystal lens array would be used to take the place of fixed lens array. Moreover, in order to increase lens power of the hexagonal LC lens array, we applied high resistance (Hi-R) layer structure on the electrode. Hi-R layer would make the gradient electric field and affect the lens profile. Also, we use panel with 801 PPI to display the integral image in our system. Hence, the consequence of full resolution 2D background with the 3D depth object forms the Hybrid Display.
A toroidal-lens designed structure for static type table-top floating image system with horizontal parallax function
(2017-07-01)
Chou, Ping-Yen
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Wu, Jui-Yi
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Hsieh, Po-Yuan
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Chen, Chun-Ho
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Yu, Zih-Sin
A new structure of horizontal parallax table-top floating image system with toroidal-lens optical film was developed. In this design, the circular arranged pico-projectors limit the angular resolution of this system and display the floating image for surrounding viewing zones. In addition, the pinhole array and toroidal-lens layer compose the optical film in the system and correspond with each other; both of them could be considered as a repeatable unit to control the spatial resolution of image. After passing through the optical film, the direction, position, shape, and divergence angle of light field could be controlled as fan ray, which has a widely scattered angle in latitude and high directivity in longitude direction. Moreover, to confirm the optical properties, the proposed structure was built in the commercially optical software, LightTools v8.3, which is widely used in the simulation of light distribution. Based on the imaging principle and the inverse light tracking method, displaying floating image with circular viewing zones would be achieved.
Automatic Organic Light-emitting Diode Display Mura Detection Model based on Human Visual Perception and Multi-resolution
(2019-01-01)
Zhu, Zhi-Yu
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Li, Jie-En
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Hsieh, Po-Yuan
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Su, Jian-Jia
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Tien, Chung-Hao
Organic light emitting diode generally has serious non-uniformity phenomena due to the instability of organic processing, called Mura. In this paper, we propose an automatic Mura detection model to mimic the human perception and detect Mura pixel-wisely. First, we extract regions of interest from the original image with different sizes of windows, and then we verify these regions by SEMU criterion. Consequently, we implement human visual properties based on the contrast sensitivity function filtering and ModelFest matching to segment Mura regions. As the result, our approach can successfully detect Mura with various sizes and shapes, which could have a great impact on the display industry.
Fast Axial-Scanning Widefield Microscopy With Constant Magnification and Resolution
(2015-11-01)
Martinez-Corral, Manuel
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Hsieh, Po-Yuan
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Doblas, Ana
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Sanchez-Ortiga, Emilio
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Saavedra, Genaro
In this paper, we propose the use of electrically-addressable lens devices for performing fast non-mechanical axial scanning when imaging three-dimensional samples. This non-mechanical method can be implemented in any commercial microscope. The approach is based on the insertion of the tunable lens at the aperture stop of the microscope objective. By tuning the voltage, a stack of depth images of 3D specimens can be captured in real time and with constant magnification and resolution. The main advantage of our technique is the possibility of performing fast axial scanning free of mechanical vibrations.
High Dynamic Depth Range for 3D Image Capturing System
(2014-01-01)
Huang, Yi-Pai
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Hsieh, Po-Yuan
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Su, Yong-Ren
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Shieh, Han-Ping D.
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光電工程學系
To detect the 3D depth information of objects in a deep scene is not so easy due to the limited depth of field (DoF) of cameras. In this paper, we proposed a 3D depth map capturing system with high dynamic depth range (HDDR). Unlike conventional extending depth of field (EDoF) method, the HDDR method will not deteriorate the image quality. By imitating an active tunable m x n lens array focusing on a sequential of imaging planes, each object in the scene would be clearly captured by at least three elemental lenses. We estimated the elemental depth maps by using the method depth from disparity individually, and then fused them into one all-in-focus depth map. Comparing with the conventional 3D cameras, the working range of HDDR system with 3x3 camera array can be extend from 90cm to 165cm.
Hybrid light field head-mounted display using time-multiplexed liquid crystal lens array for resolution enhancement
(2019-01-21)
Chou, Ping-Yen
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Wu, Dui-Yi
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Huang, Shang-Hao
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Wang, Chun-Ping
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Qin, Zong
In recent years, head-mounted display technologies have greatly advanced. In order to overcome the accommodation-convergence conflict, light field displays reconstruct three-dimensional (3D) images with a focusing cue but sacrifice resolution. In this paper, a hybrid head-mounted display system that is based on a liquid crystal microlens array is proposed. By using a time-multiplexed method, the display signals can be divided into light field and two-dimensional (2D) modes to show comfortable 3D images with high resolution compensated by the 2D image. According to the experimental results, the prototype supports a 12.28 ppd resolution in the diagonal direction, which reaches 82% of the traditional virtual reality (VR) head-mounted display (HMD). (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
LC-lens array with light field algorithm for 3D bio-medical applications
(2016-01-01)
Huang, Yi-Pai
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Hsieh, Po-Yuan
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Hassanfiroozi, Amir
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Martinez, Manuel
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Javidi, Bahram
In this paper, liquid crystal lens (LC-lens) array was utilized in 3D bio-medical applications including 3D endoscope and light field microscope. Comparing with conventional plastic lens array, which was usually placed in 3D endoscope or light field microscope system to record image disparity, our LC-lens array has higher flexibility of electrically changing its focal length. By using LC-lens array, the working distance and image quality of 3D endoscope and microscope could be enhanced. Furthermore, the 2D/3D switching ability could be achieved if we turn off/on the electrical power on LC-lens array. In 3D endoscope case, a hexagonal micro LC-lens array with 350um diameter was placed at the front end of a 1mm diameter endoscope. With applying electric field on LC-lens array, the 3D specimen would be recorded as from seven micro-cameras with different disparity. We could calculate 3D construction of specimen with those micro images. In the other hand, if we turn off the electric field on LC-lens array, the conventional high resolution 2D endoscope image would be recorded. In light field microscope case, the LC-lens array was placed in front of the CMOS sensor. The main purpose of LC-lens array is to extend the refocusing distance of light field microscope, which is usually very narrow in focused light field microscope system, by montaging many light field images sequentially focusing on different depth. With adjusting focal length of LC-lens array from 2.4mm to 2.9mm, the refocusing distance was extended from 1mm to 11.3mm. Moreover, we could use a LC wedge to electrically shift the optics axis and increase the resolution of light field.
Liquid crystal lens array for 3D microscopy and endoscope application
(2016-01-01)
Huang, Yi-Pai
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Hsieh, Po-Yuan
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Hassanfiroozi, Amir
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Chu, Chao-Yu
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Hsuan, Yun
In this paper, we demonstrate two liquid crystal (LC) lens array devices for 3D microscope and 3D endoscope applications respectively. Compared with the previous 3D biomedical system, the proposed LC lens arrays are not only switchable between 2D and 3D modes, but also are able to adjust focus in both modes. The multi-function liquid crystal lens (MFLC-lens) array with dual layer electrode has diameter 1.42 mm, which is much smaller than the conventional 3D endoscope with double fixed lenses. The hexagonal liquid crystal micro-lens array (HLC-MLA) instead of fixed micro-lens array in 3D light field microscope can extend the effective depth of field from 60 um to 780 um. To achieve the LC lens arrays, a high-resistance layer needs to be coated on the electrodes to generate an ideal gradient electric-field distribution, which can induce a lens-like form of LC molecules. The parameters and characteristics of high-resistance layer are investigated and discussed with an aim to optimize the performance of liquid crystal lens arrays.
Long working range light field microscope with fast scanning multifocal liquid crystal microlens array
(2018-04-16)
Hsieh, Po-Yuan
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Chou, Ping-Yen
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Lin, Hsiu-An
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Chu, Chao-Yu
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Huang, Cheng-Ting
The light field microscope has the potential of recording the all information of biological specimens in real time with a conventional light source. To further extend the depth of field to broaden its applications, in this paper, we proposed a multifocal high-resistance liquid crystal microlens array instead of the fixed microlens array. The developed multifocal liquid crystal microlens array can provide high quality point spread function in multiple focal lengths. By adjusting the focal length of the liquid crystal microlens array sequentially, the total working range of the light field microscope can be much extended. Furthermore, in our proposed system, the intermediate image was placed in the virtual image space of the microlens array, where the condition of the lenslets numerical aperture was considerably smaller. Consequently, a thin-cell-gap liquid crystal microlens array, with fast response time can be implemented for time-multiplexed scanning. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Projection-type see-through holographic three-dimensional display
(2016-10-03)
Wakunami, Koki
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Hsieh, Po-Yuan
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Oi, Ryutaro
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Senoh, Takanori
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Sasaki, Hisayuki
Owing to the limited spatio-temporal resolution of display devices, dynamic holographic three-dimensional displays suffer from a critical trade-off between the display size and the visual angle. Here we show a projection-type holographic three-dimensional display, in which a digitally designed holographic optical element and a digital holographic projection technique are combined to increase both factors at the same time. In the experiment, the enlarged holographic image, which is twice as large as the original display device, projected on the screen of the digitally designed holographic optical element was concentrated at the target observation area so as to increase the visual angle, which is six times as large as that for a general holographic display. Because the display size and the visual angle can be designed independently, the proposed system will accelerate the adoption of holographic three-dimensional displays in industrial applications, such as digital signage, in-car head-up displays, smart-glasses and head-mounted displays.
Three-dimensional microscopy through liquid-lens axial scanning
(2015-01-01)
Doblas, Ana
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Sanchez-Ortiga, E.
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Saavedra, G.
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Sola-Pikabea, J.
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Martinez-Corral, M.
In this contribution we propose the use of a liquid lens (LL) to perform three-dimensional (3D) imaging. Our proposed method consists on inserting the LL at the aperture stop of telecentric microscopes. The sequential depth images of 3D samples are obtained by tuning the focal length of LL. Our experimental results demonstrate that fast-axial scanning of microscopic images is obtained without varying neither the resolution capability nor the magnification of the imaging system. Furthermore, this non-mechanical approach can be easily implemented in any commercial optical microscope.