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  • Title/Summary/Keyword: Optical image

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Improvement of reconstructed image from computer generated psuedo holograms using iterative method

  • Sakanaka, Kouta;Tanaka, Kenichi
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2009.01a
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    • pp.578-582
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    • 2009
  • Computer-Generated Hologram (CGH) is generally made by Fourier Transform. CGH is made by an optical reconstruction. Computer-Generated Pseudo Hologram (CGPH) is made up Complex Hadamard Transform instead of CGH which is made by the Fourier Transform. CGPH differs from CGH in point of view the possibility of optical reconstruction. There is an advantage that it cannot be optical reconstruction, in other word, physical leakage of the confidential information is impossible. In this paper, a binary image was converted in Complex Hadamard Transform, and CGPH was made. Improvement of the reconstructed image from CGPH is done by error diffusion method and iterative method. The result that the reconstructed image is improved is shown.

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Alternative Description for Gaussian Image Plane

  • Kim, Byongoh;Lee, Sukmock
    • Journal of the Optical Society of Korea
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    • v.19 no.2
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    • pp.144-148
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    • 2015
  • An alternative description for the Gaussian image plane (GIP) of an optical system for a given object is presented, which applies to both aberration-free and non-aberration-free systems. We extend the definition of transverse magnification (TM) to the image plane (IP) displaced from the GIP and find that the TM depends linearly on the locations of both an aperture stop placed in front of the system and the IP. Hence, we redefine the GIP as the location at which the slope of the TM variance changes sign. The definition is deterministic and self-consistent and, therefore, no other parameters or measurements are needed. The derivation of this definition using a set of paraxial ray tracings and supporting experimental data for a thick bi-convex lens system is presented.

Pixel FPN Characteristics with Color-Filter and Microlens in Small Pixel Generation of CMOS Image Sensor (Color-Filter 및 Microlens를 포함한 CMOS Image Sensor의 Optical Stack 구조 별 Pixel FPN 특성 및 원인 분류)

  • Choi, Woonil;Lee, Hi-Deok
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.25 no.11
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    • pp.857-861
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    • 2012
  • FPN (fixed-pattern-noise) mainly comes from the device or pattern mismatches in pixel and color filter, pixel photodiode leakage in CMOS image sensor. In this paper, optical stack module related pixel FPN was investigated and the classification of pixel FPN contribution with the individual optical module process was presented. The methodology and procedure would be helpful in reducing the greater pixel FPN and distinguishing the complex FPN sources with respect to various noise factors.

Qualitative Analysis of Film Thickness in Elastohydrodynamic Lubrication (탄성 유체 윤활에서의 유막 두께 측정에 관한 정성적 분석)

  • 최언진;박경근;장시열
    • Tribology and Lubricants
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    • v.16 no.5
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    • pp.317-323
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    • 2000
  • The film thickness and shape of elastohydrodynamic lubrication is measured by optical interferometer, which is the most precise method for EHL film measurement. However, the interpretation of the image pattern from optical viscometer is not simple for two-dimensional shape. A newly developed method of image processing makes it possible to evaluate the film thickness and shape in every point of contact region with two dimensional aspects. In this study, we captured the film shape of EHL film by the monochromatic incident light and analyzed the film thickness with the image processing method, which uses phase shift method. From the values of intensity in fringes, the qualitative feature of film thickness in the contact area are obtained by using Zernike polynomial

Development of Image-space Telecentric Lens for Intra-Oral 3D Scanner

  • Kim, Tae Young;Shin, Min-Ho;Chang, Ryungkee;Kim, Young-Joo
    • Journal of the Optical Society of Korea
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    • v.19 no.3
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    • pp.303-310
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    • 2015
  • An image-space telecentric lens for an intra-oral 3D scanner was designed and fabricated for dental application. Since a telecentric function can provide the same results regardless of image plane position, it helps to realize a more accurate image for an intra-oral scanner. The performance of the designed lens meets the required properties for HD resolution. In particular, lateral color is corrected within 1 pixel. This system achieves depth of focus of more than 3 mm. For user convenience, the developed system consists of a prism part and an imaging part. Both parts are optimized to reduce the front size and weight of the system. In order to make the parallax sights, parallax angle was determined to be 8 degrees between two optical systems.

Analysis of Correction Displacements of the Projected Distortion Image (투사된 영상에 대한 화면 변위 보정에 관한 연구)

  • Chi, Yongseok
    • Journal of the Semiconductor & Display Technology
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    • v.20 no.3
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    • pp.18-21
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    • 2021
  • This paper analyzes the distortion correction of the in the micro DMD(digital micro mirror device) projector system using 0.25 or less optical throwing distance ratio. The distortion of projected image occurs depending on the performance of the optical lens, the installation location of the projection system, and the tilt of the screen. This study analyzed the physical tilt values influencing of the distortion of projected image, removed the tilt distortion of throwing distance ratio optical lens, and adjusted the distortion image by the simulation of calibration displacements. The results of this study demonstrated within 5% TV distortion reference. Moreover, the correction method reduced the pin-distortion correction of projection system.

A Method to Prevent Transfer Device of Image Stabilizer from Blunting by Artificial Vibration (가진입력에 의한 손떨림 보정용 이송장치의 둔화현상 방지대책)

  • Yeom, Dong-Hae
    • Journal of Institute of Control, Robotics and Systems
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    • v.15 no.11
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    • pp.1076-1079
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    • 2009
  • This article deals with an optical image stabilizer which moves an image sensor in the direction of cancelling the vibration caused by hand shaking to prevent a photographed image from blurring. The ball-guide way method adopted as a transfer device of the image sensor is easy to be manufactured because of its simple structure and is suitable to minimize the friction between mechanisms, but has weakness of a chance of physical defect such as groove and rising. In case that the movement of the transfer device equipped with the image sensor is blunted because a ball is stuck in defects of guide way, the performance of the image stabilizer falls down drastically. We propose a method to prevent the transfer device from blunting by applying artificial vibration. At this time, the artificial vibration should be designed under consideration of dynamic characteristics and specifications of the system to be discriminated from the vibration caused by hand shaking.

Simple Image-Separation Method for Measuring Two-Phase Flow of Freely Rising Single Bubble (상승하는 단일 버블 이상유동의 PIV 계측을 위한 영상분리기법)

  • Park Sang-min;Jin Song-wan;Kim Won-tae;Sung Jae-yong;Yoo Jung-Yul
    • 한국가시화정보학회:학술대회논문집
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    • 2002.11a
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    • pp.7-10
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    • 2002
  • A novel two-phase PIV algorithm using a single camera has been proposed, which introduces a method of image-separation into respective phase images, and is applied to freely rising single bubble. Gas bubble, tracer particle and background each have different gray intensity ranges on the same image frame when reflection and dispersion in the phase interface are intrinsically eliminated by optical filters and fluorescent material. Further, the signals of the two phases do not interfere with each other. Gas phase velocities are obtained from the separated bubble image by applying the two-frame PTV. On the other hand, liquid phase velocities are obtained from the tracer particle image by applying the cross-correlation algorithm. Moreover, in order to increase the SNR (signal-to-noise ratio) of the cross-correlation of tracer particle image, image enhancement is employed.

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The Developement of Small 360° Oral Scanner Lens Module (소형 360° 구강 스캐너 렌즈 모듈 개발)

  • Kwak, Dong-Hoon;Lee, Sun-Gu;Lee, Seung-Ho
    • Journal of IKEEE
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    • v.22 no.3
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    • pp.858-861
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    • 2018
  • In this paper, we propose the development of a small 360 oral scanner lens module. The proposed small 360 oral scanner lens module consists of a small 360 high resolution(4MegaPixel) lens optical system, a 15mm image sensor unit, and a small 360 mouth scanner lens external shape. A small 360 high resolution lens optical system produces a total of nine lenses, the outer diameter of the lens not less than 15mm for use by children through the ages of adulthood. Light drawn by a small 360 high resolution lens optical system is 90 flexion so that image images are delivered to image sensors. The 15mm image sensor unit sends the converted value to the ISP(Image Signal Processor) of the embedded board after an image array through the column and the row address of the image sensor. The small 360 mouth scanner lens outer shape was designed to fix the race to the developed lens. Results from authorized testing agencies to assess the performance of proposed small 360 oral scanner lens modules, The optical resolving power of 360 lens was more than 30% at 150 cycles/mm, 360 lens angle was 360 in vertical direction, 4285 in vertical direction, and lens distortion rate was 5% or less. It produced the same result as the world's highest level.