• Title/Summary/Keyword: Focusing Error

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REFOCUSING FOR ON-ORBIT MTF COMPENSATION OF REMOTE SENSING CAMERA

  • Jang Hong-Sul;Jeong Dae-Jun;Lee Seunghoon
    • Proceedings of the KSRS Conference
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    • 2005.10a
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    • pp.601-603
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    • 2005
  • Refocusing methods are used to compensate optical performance degradation of high resolution satellite camera during on-orbit operation. Due to mechanical vibration during launch and thermal vacuum environment of space where camera is exposed, the alignment of optical system may have error. The focusing error is dominant of misalignment and caused by the de-space error of secondary mirror of catoptric camera, which is most sensitive to vibration and space environment. The high resolution camera of SPOT, Pleiades and KOMPSAT2 have refocusing device to adjust focusing during orbital operation while QuickBird of US does not use on orbit refocusing method. For the Korsch type optical configuration which is preferred for large aperture space remote sensing camera, secondary mirror and folding mirror are available as refocusing element.

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Autofocus system for off-line focusing error compensation in micro laser fabrication process (레이저 미세가공용 자동초점장치를 이용한 오프라인 초점 오차 보상에 관한 연구)

  • Kim, Sang-In;Kim, Ho-Sang
    • Journal of the Korean Society for Precision Engineering
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    • v.26 no.6
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    • pp.50-58
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    • 2009
  • Micro laser fabrication techniques can potentially be used for the manufacture of microstructures on the thin flat surfaces with large diameter that are frequently used in semiconductor industries. However, the large size of wafers can cause the degraded machining accuracy of the surface because it can be tilted or distorted by geometric errors of machines or the holding fixtures, etc. To overcome these errors the off-line focusing error compensation method is proposed. By using confocal autofocus system, the focusing error profile of machined surface is measured along the pre-determined path and can be compensated at the next machining process by making the corrected motion trajectories. The experimental results for silicon wafers and invar flat surfaces show that the proposed method can compensate the focusing error within the level of below $6.9{\mu}m$ that is the depth of focus required for the laser micromachining process.

Design of Optical Disk Profile for Minimizing the Focusing Error (포커싱 에러를 최소화하기 위한 광디스크의 형상설계)

  • Hong, Seok-Joon;Jee, Jung-Geun;Lee, Jong-Soo;Park, No-Cheol;Park, Young-Pil
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.11b
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    • pp.1015-1021
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    • 2002
  • Optical disk is the media which is used generally in data storage device, but it has a disadvantage in the vibration by spinning and the shock. For overcoming these disadvantage, we must control the optical disk to minimize the focusing error and tacking error. The present study investigates the disk profile for minimizing the focusing error subjected to environmental shock and weight of the disk. In this study, the disk is assumed to be a cantilever beam to determine the disk profile for the minimum displacement as to the shock considering only the first mode. Also, for the optimally determined profile by ADS program this paper recalculate the robust caltilever profile by using orthogonal array and ANOM.

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Beam Focusing Performance of Electrostatic Lens using SIMION Simulator (SIMION 시뮬레이터를 이용한 정전렌즈의 빔 집속 성능)

  • Oh, Maeng-Ho;Jeong, In-Sung;Lee, Jong-Hang
    • Journal of the Korean Society for Precision Engineering
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    • v.26 no.4
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    • pp.128-133
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    • 2009
  • Focused-ion-beam (FIB) system is capable of both machining and measuring in nano-scale; hence nano-scale focusing quality is important. This paper investigates design parameters of two electrostatic lenses in order to achieve the best ion beam focusing performance. Commercial SIMION simulator is used to optimize the dimensions of the condenser and objective lenses and investigate the influence of assembly error on focusing quality The simulation results show that the beam focusing quality is not influenced by angle deviation within ${\pm}0.02\;deg$ and geometrical eccentricity within ${\pm}50$ micrometers.

Design of Optical Disk Profile for Minimizing the Focusing Error (포커싱 에러를 최소화하기 위한 광디스크 형상설계)

  • Hong, Seok-Joon;Jee, Jung-Guen;Park, No-Cheol;Lee, Jongsoo;Park, Young-Pil
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.11a
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    • pp.398.2-398
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    • 2002
  • Optical disk is the media which is used generally in data storage device, but it has a disadvantage in the vibration by the spinning and the shock. For overcoming these disadvantage, we must control the optical disk to minimize the focusing and tracking error. The present study investigates the disk profile fur minimizing the focusing error subjected to environmental shock and weight of the disk. (omitted)

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Noise Insensitive Focusing Index using Adaptive Weights (적응적 가중치를 이용한 노이즈에 강인한 초점값 연산자)

  • Choi, Jong-Seong;Kang, Hee;Kang, Moon-Gi
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.47 no.4
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    • pp.90-96
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    • 2010
  • The focusing system is an important factor to determine the imaging quality of a digital imaging system. The focusing system consist of measuring the focusing index with high frequency energy of an image and controlling the movement of the focusing lens based on the computed focusing index. The computation of the focusing index is a key aspect in implementing the focusing system and the noise of the image cause the error in the sharpness evaluation of the image. To reduce this error, the noise under the low illumination condition is considered. A noise insensitive focusing index using adaptive weights is proposed in this paper. This measure determines the sharpness of an image using the spatially adaptive weights based on the local statistics of the image and noise. Experimental results under the condition without and with the noise verify the performance of the proposed method.

The Identification of Vibration Sources in Optical Disk Drive Using PCF Method (PCF 기법을 이용한 광디스크 드라이브의 진동원 규명)

  • 함경훈;장영배;박노철;박영필
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.05a
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    • pp.127-133
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    • 2002
  • After the vibration source is searched in optical disk drive as an information storage device broadly used the influence of it against FES(Focusing Error Signal) which is a kind of positioning error of pick up from the circuit is carefully examined. For that Purpose, partial coherence function method is applied on a simple multi-degree of freedom model made for the theoretical verification and it is practically introduced in optical disk drive for analyzing the effect of vibration source. Finally, partial coherence output spectrum is attentively observed in order to know which vibration source is a great influence on FES.

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A Study on the Evaluation of the Optical Head of a Near-field Optical Recording System and Interference Pattern Analysis (근접장 광기록 헤드의 광학적 성능 평가와 정렬 오차에 대한 간섭 무늬 패턴 분석에 대한 연구)

  • Yoon Hyoung Kil;Gweon Dae Gab;Lee Jun Hee;Jung Jae Hwa;Oh Hyung Ryeol
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.5 s.170
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    • pp.80-86
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    • 2005
  • Optical performance evaluation results and an interference fringe pattern analysis of alignment errors for an optical head of a near-field receding (NFR) system are presented. The focusing unit is an optical head of a NFR system and is composed of a solid immersion lens (SIL) and an objective lens (OL). Generally, the size of the focusing unit is smaller than that of the conventional optical recording head. Hence there are difficulties to assemble the small focusing unit precisely. We composed an evaluation system with an interferometer and evaluated some focusing unit samples aligned and assembled by manual and present the obtained results. Using the conventional optical tool, Code V, a tolerance analysis of the alignment error between the SIL and the objective lens and an interference pattern analysis for the assembly error are executed. Then, through an analysis of the simulation results, the conceptual auto-alignment methodology using a neural network approach is considered.

A Study on the Shift Register-Based Multi Channel Ultrasonic Focusing Delay Control Method using a CPLD for Ultrasonic Tactile Implementation (초음파 촉각 구현을 위한 CPLD를 사용한 Shift Register기반 다채널 초음파 집속 지연 제어 방법에 대한 연구)

  • Shin, Duck-Shick;Park, Jun-Heon;Lim, Young-Cheol;Choi, Joon-Ho
    • Journal of Sensor Science and Technology
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    • v.31 no.5
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    • pp.324-329
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    • 2022
  • This paper proposes a shift-register-based multichannel ultrasonic focusing delay control method using a complex programmable logic device (CPLD) for a high resolution of ultrasonic focusing system. The proposed method can achieve the ultrasonic focusing through the delay control of driving signals of each ultrasonic transducer of an ultrasonic array. The delay of the driving signals of all ultrasonic channels can be controlled by setting the shift register in the CPLD. The experiment verified that the frequency of the clock used for the delay control increased, the error of the focusing point decreased, and the diameter of the focusing point decreased as the length of the shift register in the proposed method. The proposed method used only one CPLD for ultrasonic focusing and did not require to use complex hardware circuits. Therefore, the resources required for the design of an ultrasonic focusing system could be reduced. The proposed method can be applied to the fields of human computer interaction (HCI), virtual reality (VR) and augmented reality (AR).