• Title/Summary/Keyword: Optical image

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QPSK Modulation Based Optical Image Cryptosystem Using Phase-shifting Digital Holography

  • Jeon, Seok-Hee;Gil, Sang-Keun
    • Journal of the Optical Society of Korea
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    • v.14 no.2
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    • pp.97-103
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    • 2010
  • We propose a new technique for the optical encryption of gray-level optical images digitized into 8-bits binary data by ASCII encoding followed by QPSK modulation. We made an encrypted digital hologram with a security key by using 2-step phase-shifting digital holography, and the encrypted digital hologram is recorded on a CCD camera with 256 gray-level quantized intensities. With these encrypted digital holograms, the phase values are reconstructed by the same security key and are decrypted into the original gray-level optical image by demodulation and decoding. Simulation results show that the proposed method can be used for cryptosystems and security systems.

Lens Design of Camera through Optimization of the Third Order Seidel Aberration and Statistical Tolerance Analysis

  • Lee, Kyutae;Kim, Young-Joo;Kim, Youngwoon
    • Journal of the Optical Society of Korea
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    • v.20 no.3
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    • pp.413-426
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    • 2016
  • There has been much advancement in the field of aerial cameras for geographical features with the help of drones, image processing power and computer aided optical programs. In this study, we propose a new optical lens design technique which minimizes the amount of ‘the third order Seidel aberration’ for enhancing MTF. In addition, we suggest a new optical lens design which stabilizes the mass-production yield through R.S.M and has robustness secure through the Taguchi method. Eventually, the image processing algorithm of stereo matching is implemented in order to evaluate whether the proposed lens design result meets adequate specifications for the use of dual aerial photographs or not. This paper provides good guidance for the optical design by development of experiments.

Measurement of Focal Length for Off-axis Optical Systems

  • Choe, Se-woon;Ryu, Jaemyung
    • Current Optics and Photonics
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    • v.5 no.4
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    • pp.402-408
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    • 2021
  • An off-axis system refers to an optical system in which the optical axis and normal vector at the vertex of each surface do not match. The most important specification in an optical system is its focal length. Among the various methods for measuring the focal length, the most suitable method for the off-axis system is the method that adopts magnification. However, head-mounted display (HMD) optics must be measured while considering the virtual image distance, which is not infinity owing to product characteristics. For the virtual image distance, a camera with a focusing function was used. By measuring HMD optics via this magnification method, the error generated in this measurement was 0.68% of the HMD's focal length, which is within the 1%-3% range of the conventionally permitted design error for the focal length allowed at the optical design stage. Therefore, it can be verified that the measurement accuracy of the method proposed in this study is sufficiently feasible in practice.

Improvement of the Multiple Image Encryption Capacity Using QR Code as a Data Container

  • Bai, Xing;Hu, Jianping;Yuan, Sheng;Wang, Jinchao;Wang, Jing;Zhou, Xin
    • Current Optics and Photonics
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    • v.4 no.4
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    • pp.302-309
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    • 2020
  • An image encryption scheme based on the quick response (QR) code as a data container has aroused wide interest due to the lossless recovery of the decrypted image. In this paper, we apply this method to multi-image encryption. However, since the decrypted image is affected by crosstalk noise, the number of multi-image encryptions is severely limited. To solve this problem, we analyzed the performance of QR code as a data container, and processed the decrypted QR code using the proposed method, so that the number of multi-image encryptions is effectively increased. Finally, we implemented a large image (256 × 256) encryption and decryption.

Design and fabrication of wafer scale microlens array for image sensor using UV-imprinting (UV 임프린팅을 이용한 이미지 센서용 웨이퍼 스케일 마이크로렌즈 어레이 설계 및 제작)

  • Kim, Ho-Kwan;Kim, Seok-Min;Lim, Ji-Seok;Kang, Shin-Ill
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2007.10a
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    • pp.100-103
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    • 2007
  • A microlens array has been required to improve light conversion efficiency in image sensors. A microlens array can be usually fabricated by photoresist reflow, hot-embossing, micro injection molding, and UV-imprinting. Among these processes, a UV-imprinting, which is operated at room temperature with relatively low applied pressure, can be a desirable process to integrate microlens array on image sensors, because this process provides the components with low thermal expansion, enhanced stability, and low birefringence, furthermore, it is more suitable for mass production of high quality microlens array. In this study, to analyze the optical properties of the wafer scale microlens array integrated image sensor, another wafer scale simulated image sensor chip array was designed and fabricated. An aspherical square microlens was designed and integrated on a simulated image sensor chip array using a UV-imprinting process. Finally, the optical performances were measured and analyzed.

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Identification and Correction of Microlens-array Error in an Integral-imaging-microscopy System

  • Imtiaz, Shariar Md;Kwon, Ki-Chul;Alam, Md. Shahinur;Hossain, Md. Biddut;Changsup, Nam;Kim, Nam
    • Current Optics and Photonics
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    • v.5 no.5
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    • pp.524-531
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    • 2021
  • In an integral-imaging microscopy (IIM) system, a microlens array (MLA) is the primary optical element; however, surface errors impede the resolution of a raw image's details. Calibration is a major concern with regard to incorrect projection of the light rays. A ray-tracing-based calibration method for an IIM camera is proposed, to address four errors: MLA decentering, rotational, translational, and subimage-scaling errors. All of these parameters are evaluated using the reference image obtained from the ray-traced white image. The areas and center points of the microlens are estimated using an "8-connected" and a "center-of-gravity" method respectively. The proposed approach significantly improves the rectified-image quality and nonlinear image brightness for an IIM system. Numerical and optical experiments on multiple real objects demonstrate the robustness and effectiveness of our proposed method, which achieves on average a 35% improvement in brightness for an IIM raw image.

Image Analysis for the Simultaneous Measurement of Underwater Flow Velocity and Direction (수중 유속 및 유향의 동시 측정을 위한 이미지 분석 기술에 관한 연구)

  • Dongmin Seo;Sangwoo Oh;Sung-Hoon Byun
    • Journal of Sensor Science and Technology
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    • v.32 no.5
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    • pp.307-312
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    • 2023
  • To measure the flow velocity and direction in the near field of an unmanned underwater vehicle, an optical measurement unit containing an image sensor and a phosphor-integrated pillar that mimics the neuromasts of a fish was constructed. To analyze pillar movement, which changes with fluid flow, fluorescence image analysis was conducted. To analyze the flow velocity, mean force analysis, which could determine the relationship between the light intensity of a fluorescence image and an external force, and length-force analysis, which could determine the distance between the center points of two fluorescence images, were employed. Additionally, angle analysis that can determine the angles at which pixels of a digital image change was selected to analyze the direction of fluid flow. The flow velocity analysis results showed a high correlation of 0.977 between the external force and the light intensity of the fluorescence image, and in the case of direction analysis, omnidirectional movement could be analyzed. Through this study, we confirmed the effectiveness of optical flow sensors equipped with phosphor-integrated pillars.

Real time optical image generation using phase grating with simulated annealing algorithm (Simulated Annealing 알고리즘에 의한 위상격자를 이용한 실시간 광 영상 생성)

  • 김철수;김정우;배장근;김수중
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.33B no.6
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    • pp.149-155
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    • 1996
  • In this paper, we designed binary phase grating with SA (simulated annealing) algorithm for image generation, and used LCTV(liquid crystal television) as phase modulator. We generated optical image using LCTV which controlled by personal computer in real time. Many parameters in SA algorithm are determined by average deviation of the cost function, not experimental method. It was confirmed that the LCTV could be used as a phase modulator through mach-zehnder interferometering experiment. The various optical images are generated in real itme by fourier transforming of the phase gratings on LCTV which is controlled by personal computer and they can be used for optical interconnection in a neural network and addressing information in a volume hologram etc.

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Development of an Optical System for Iris Photographing (홍채 촬영용 광학계 개발)

  • Lee, Dong-Hee
    • Journal of Korean Ophthalmic Optics Society
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    • v.8 no.2
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    • pp.177-183
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    • 2003
  • We tried to design and manufacture an iris photographing optical-system which is used in the Oriental medicine or medical diagnostics. The whole system consists of a light source part, an image focusing part, a CCD transfer part and a diagnosis S/W. We designed the image focusing part to the reduction optical-system with 0.58X magnification of which the chromatic aberration is removed by using materials of FD60 and BACD5. The image focusing part's localization did big contribution in coot reduction of products. The manufactured iris photographing optical-system had superior performance in aspect that has stereoscopic effects of images in comparison with the foreigner's.

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Realization of CCD Image Sensor Driver for Spectral-Domain Optical Measurement System (Spectral-Domain 광 계측을 위한 CCD 이미지 센서 드라이버 제작)

  • Kim, Hoon-Sup;Lee, Jung-Ryul;Eom, Jin-Seob
    • Journal of Industrial Technology
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    • v.27 no.B
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    • pp.125-128
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    • 2007
  • This paper presents Spectral-Domain optical measurement system using self-fabricated CCD sensor driver. The light source is a high brightness white LED and the detector is a 2048 array typed CCD image sensor. I have fabricated the CCD sensor driver to generate four pulse signals, which are the CCD-driving pulses. Using this Spectral Domain optical measurement system, the distance value between the reference mirror and the sample mirror can be obtained successfully.

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