Holographic data storage system is one of next generation high density optical memories. Thereby storing multiple data pages using multiplexing method in one spot, we can achieve high store density and fast access time. However, for uniform writing, we must control exposure time properly by the change of writing material characteristics. Many studies have been investigated about exposure time scheduling. However, once it is decided, we cannot change the scheduled time. Therefore, it is hard to obtain uniform data intensity. In this study, we propose exposure time control method using additional red beam as the monitoring signal. Through reconstructed red beam intensity in real time, we can adjust exposure time by the writing condition change. We construct compensation method mathematically and verify the feasibility of proposed method through the experiments.

Holographic Data Storage

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Whole Body Interaction Using the Grounded Bar Interface

Lecture notes in computer science (2011)

Bong‐gyu Jang Hyunseok Yang Gerard J. Kim

Interface (matter)

Bar (unit)

10.1007/978-3-642-22021-0_27

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Speckle Noise Reduction Algorithm for Parallel Phase-Shift Digital Holography

Imaging and Applied Optics (2016)

Woooyoung Jeong Jae-Seong Lee Kyungchan Son Hyunseok Yang

To reduce speckle noise of parallel phase-shift digital holography, new interpolation method is adapted and it reduces speckle noise in real time. Simulation results show that image has low speckle noise and high SNR.

Speckle noise

Digital holography

Interpolation

10.1364/math.2016.mt1h.3

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Citations (1)

Angle Servo Method for Holographic Data Storage System using Angle Multiplexing

Transactions of the Society of Information Storage Systems (2011)

Nak-Yeong Kim Jang-Hyun Kim Sung-Yong Lim Cho-Lok Han Jaeseong Lee

A control method for the angle servo of reference beam during reading recoded data images of a holographic data storage system is presented. The recording scheme with angle offset is adopted in order to verify the proposed angle servo. Using this recording scheme, the angle error signal is generated and we can implement the angle servo. Experiments have been performed on recording and reading data images to compensate Bragg angle mismatch.

Viewing angle

Servomechanism

SIGNAL (programming language)

10.9797/tsiss.2011.7.1.001

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Opto-mechatronics issues in solid immersion lens based near-field recording

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (2007)

No-Cheol Park Yong-Joong Yoon Yong-Hyun Lee Joong‐Gon Kim Wan-Chin Kim

We analyzed the effects of an external shock on a collision problem in a solid immersion lens (SIL) based near-field recording (NFR) through a shock response analysis and proposed a possible solution to this problem with adopting a protector and safety mode. With this proposed method the collision between SIL and media can be avoided. We showed possible solution for contamination problem in SIL based NFR through a numerical air flow analysis. We also introduced possible solid immersion lens designs to increase the fabrication and assembly tolerances of an optical head with replicated lens. Potentially, these research results could advance NFR technology for commercial product.

Immersion

10.1117/12.738954

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Discrete linear quadratic output feedback control with integrator for holographic data storage system

International Conference on Control, Automation and Systems (2008)

YongHee Lee Sang-Hoon Kim Jang Hyun Kim Hyunseok Yang Young-Pil Park

In this paper, we focus on effects of radial deviation on the disk and propose a tracking error compensation method for the holographic data storage system (HDSS) that uses a disk type media. In our HDSS, when the tracking error is detected, the error compensation is achieved by a piezo actuator. A tracking servo controller is suggested, and the validity of the servo control is verified with simulation results.

Tracking error

Servomechanism

Optical disc

Tracking (education)

10.1109/iccas.2008.4694533

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Application of SIL based Near Field Recording Technology to High Speed Nano Patterning

Nonlinear Optics (2011)

No-Cheol Park Byung-Kwon Min Young-Pil Park Hyunseok Yang Kyoung-Su Park

Photoresist

Line width

Nanometre

Immersion lithography

10.1364/isom_ods.2011.otua2

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Speckle noise reduction for digital holographic images using multi-scale convolutional neural networks

Optics Letters (2018)

Wonseok Jeon Wooyoung Jeong Kyungchan Son Hyunseok Yang

In this Letter, we propose a fast speckle noise reduction method with only a single reconstructed image based on convolutional neural networks. The proposed network has multi-sized kernels that can capture the speckle noise component effectively from digital holographic images. For robust noise reduction performance, the network is trained with a large noisy image dataset that has object-dependent noise and a wide range of noise levels. The experimental results show the fast, robust, and outstanding speckle noise reduction performance of the proposed approach.

Speckle noise

Digital holography

Image noise

10.1364/ol.43.004240

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Citations (76)

Prediction method of an in-pipe robot's orientation to pass in a curved pipe

2009 ICCAS-SICE (2009)

Jungwan Park Sang Yong Park Dongwoo Lee Hyunseok Yang

Pipe systems are infrastructure of a modern society. Since inner conditions of pipe systems could affect quality of transferring mass, inspecting and maintaining pipe system is an important issue. Many in-pipe robots have been introduced and are under developing to resolve the problem. Pipe systems are composed of different shaped pipes such as straight, curved and branch pipes. Therefore, moving algorithms are introduced. In order to move in a bent pipe, detecting the orientation of an in-pipe robot is an important problem. In this paper, we propose a predicting method of in-pipe robot's orientation, and verify it by experiments

Nominal Pipe Size

Pipe network analysis

Micro-loop heat pipe

Trenchless technology

Water pipe

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