Jung-Sik Koo

Compensation of image distortion in Fresnel lens-based 3D projection display system using a curved screen

As an approach for a 3D real image display system without special glasses, a Fresnel lens-based 3D rear-projection display system is implemented. In this display system, the conventional 2D video image is projected into the air through some projection optics, a screen and a pair of Fresnel lens and as a result, it can form a floating video image having a real depth. But in the conventional floating display system some image distortions might be occurred in the floating image plane, in which a flat screen has been mostly used for providing an adequate input image plane. In this paper, as a new approach to alleviate this image distortion problem, a Fresnel lens-based floating display system employing a curved screen is suggested and some computer simulations and practical experiments are carried out. That is, optimum design parameters of a curved screen for reducing image distortion is found out through some computer simulation using an optics design program of Light Tools and its performance in the floating system is experimentally verified and compared with those of the flat screen. Experimental results with a curved screen shows some decrease of image distortion in the floating image plane by comparing with that of the flat screen. This feasibility test suggests a possibility of implementation of a new Fresnel lens-based 3D projection display system with improved image distortion using a curved screen.

Implementation of VHOE-based multiview stereoscopic 3D display system

In this paper, a photopolymer-based VHOE is optimally manufactured and using this VHOE, an experimental model of the VHOE-based 8-view stereoscopic display system is implemented. That is, the VHOE is optically made by angle-multiplexed recording of 8-views diffraction gratings in the Duponts photopolymer(HRF-150-100) using an optimized exposure-time scheduling scheme and then, the VHOE-based 8-view stereoscopic display system is implemented, in which the incident angles of the diffracted reference beams of the VHOE are sequentially synchronized with the respective 8-view stereo images displayed on the LCD panel. From some experimental results using 8-view test images, it is found that 8-view stereo images can be diffracted to the eight different directions corresponding to the incident angles of the reference beams and there is some disparity between the stereo images. From these experimental results, a possibility of implementing the VHOE-based multi-view stereoscopic 3D display system is also suggested.

A Novel Three-Dimensional Visual Inspection Scheme for Defect Detection of Transparent Materials Based on the Digital Holographic Microscopy

In the conventional visual inspection system with naked eyes, a camera has been mostly employed for detection of scratches or glass dust, so that it may be difficult to discriminate between the high-grade and the low-grade mass components. Therefore, here we propose a novel three-dimensional (3-D) visual inspection scheme for effective detection of defects of the transparent materials based on a digital holographic microscopy, which is optically implemented as a form of transmission-typed shearing interferometer. In the proposed method, quantitative data are obtained by converting the phase information of the transparent touch panel or the substrate glass into its depth or thickness information. Then, by using 3-D data extracted from the depth or thickness information of transparent touch panel or substrate glass, we can accurately discriminate between the high-grade and the low-grade mass components. Experiments with test objects confirm the feasibility of the proposed method in the practical applications. Based on these experimental results, the proposed method expects to improve the production yield rate of the original mother glass of the transparent touch panel or the substrate glass used in the LCM.

Measurement and Analysis of Three-Dimensional Shape Variations of Microalgae Based on a Digital Holographic Microscopy for Prediction of the Spread Point of Red Tide

Thus far, a general approach to prevent the occurrence of the red tide phenomena and to minimize its resultant damage is to predict the spread point of the red tide. For that, conventionally a set of microalgae are periodically sampled from several shore areas and their numbers of microalgae per unit area are simply counted to predict the threshold level of the spread point of the red tide. However, this approach cannot foresee a decisive symptom for spreading of the red tide in advance. Accordingly, in this paper, we propose a novel approach for accurate prediction of the spread point of red tide by measuring and analyzing the three-dimensional (3-D) volume information of the microalgae with the digital holographic microscopy (DHM). This volume information of the microalgae can be converted into the thickness information through digital holographic reconstruction. With these thickness data, the volume variations of microalgae in time can be finally measured and analyzed. Experiments with several samples of microalgae may confirm the feasibility of the proposed method in the practical application.

Modification of Commercial LCD Video Projector for High-Resolution Spatial Light Modulator

In this paper, a new high-resolution (XGA) SLM is implemented through modification of a commercial TFT-LCD beam projector and its optical modulation characteristics are analyzed as well. The optic module, projection lamp and cooling fans are removed from the beam projector and instead, the electric circuits to compensate their removal are manufactured and inserted into the beam projector, a new high-resolution SLM is finally implemented. Some experiments on the optical modulation characteristics of the implemented SLM have been carried out by using the Mach-Zehnder interferometer. These experimental results show a good optical linearity in amplitude and phase modulation and as a result, the implemented LC-SLM is suggested as a new low-cost, high-resolution input and filter devices for the optical information processing systems.