• Journal of the Optical Society of Korea
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• 제16권3호
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• pp.210-214
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• 2012

We propose and experimentally demonstrate a method for extension of measurement range in a Brillouin optical correlation domain analysis sensor system without resolution deterioration. In the experiment, a 300 m measurement range with about 8 cm spatial resolution was successfully obtained by cascading three different kinds of fibers as a sensing element.

• Current Optics and Photonics
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• 제4권4호
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• pp.336-344
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• 2020

Exact optical characterization of virtual and augmented reality devices using conventional luminance measuring methods is a time-consuming process. A new measurement method is proposed to estimate in a relatively short time the boundary of ray trajectories emitting from a specific position on a virtual images. It is assumed that the virtual image can be modeled to be formed in front of one's eyes and seen through some optical aperture (field stop) that limits the field of view. Circular and rectangular shaped virtual images were investigated. From the estimated ray boundary, optical characteristics, such as the viewing direction and three dimensional range inside which a eye can observe the specified positions of the virtual image, were derived. The proposed method can provide useful data for avoiding the unnecessary measurements required for the previously reported method. Therefore, this method can be complementary to the previously reported method for reducing the whole measurement time of optical characteristics.

• Journal of the Optical Society of Korea
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• 제14권3호
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• pp.199-203
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• 2010

A mobile direct detection Doppler LIDAR based on molecular backscattering for measurement of wind in the stratosphere has been developed in Hefei, China. First, the principle of wind measurement with direct detection Doppler LIDAR is presented. Then the configuration of the LIDAR system is described. Finally, the primary experimental results are provided and analyzed. The results indicate that the detection range of the designed Doppler LIDAR reached 50 km altitude, and there is good consistency between the molecular Doppler wind LIDAR(DWL) and the wind profile radar(WPR) in the low troposphere.

• 한국광학회:학술대회논문집
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• 한국광학회 2003년도 하계학술발표회
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• pp.204-205
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• 2003

We demonstrate a novel OFDR system with compactness and short measurement time based on the use of a wavelength-swept mode-locked fiber laser. The optical source uses an intra-cavity tunable Fabry-Perot filter as a tuning element. The fiber laser sweeps 20 nm in less than 10 ms. Spatial resolution of 100 fm and total measurement range of several centimeters are demonstrate

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1446-1449
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• 2005

The purpose of this study is the real-time shape measurement of three-dimensional object by using color coded information. The paper relates to non-contact optical measurements of surface profiles or displacements, because of optical measurement systems are advantageous over using mechanical sensing, their relatively high speed and non-destructive capabilities. Therefore is particularly useful for three dimensional sensing which requires high horizontal and vertical resolution of measurements over a wide range thereof. Each a red, blue, green by using a inherence colors of hue value are good point.

• Journal of the Optical Society of Korea
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• 제17권5호
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• pp.392-398
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• 2013

As the essential techniques for the CD (Critical Dimension) measurement of the LCD pattern, there are various modules such as an optics design, auto-focus [1-4], and precise edge detection. Since the operation of image enhancement to improve the CD measurement repeatability, a ring type of the reflected lighting optics is devised. It has a simpler structure than the transmission light optics, but it delivers the same output. The edge detection is the most essential function of the CD measurements. The CD measurement is a vital inspection for LCDs [5-6] and semiconductors [7-8] to improve the production yield rate, there are numbers of techniques to measure the CD. So in this study, a new subpixel algorithm is developed through facet modeling, which complements the previous sub-pixel edge detection algorithm. Currently this CD measurement system is being used in LCD manufacturing systems for repeatability of less than 30 nm.

• Journal of Astronomy and Space Sciences
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• 제27권4호
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• pp.337-343
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• 2010

Optical observation system provides angle-only measurement for orbit determination of space object. Range measurement can be directly acquired using laser ranging or tone ranging system. Initial orbit determination (IOD) by using angle- only data set shows discrepancy according to the measurement time interval. To solve this problem, range measurement data should be added for IOD. In this study, two-site optical observation was used to derive the range information. We have observed nine geostationary earth orbit satellites by using two-site optical observation system. The determination result of the range shows the accuracy over 99.5% compared to the results from the satellite tool kit simulation. And we confirmed that the orbit determination by the Herrick-Gibbs method with the range information obtained from the two-site observation is more accurate than the orbit determination by Gauss method with the one-site observation. For more accurate two-site optical observation, a baseline should satisfy an optimal condition of length and more precise observation system needed.

• 한국광학회지
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• 제15권2호
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• pp.104-108
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• 2004

폐경로를 통한 Fabry-Perot 레이저의 자기궤환 레이저 발진(self-seeding laser oscillation)을 이용하여 구조가 간단하고 경제적인 색분산(chromatic dispersion) 측정법을 제안하였다. 저가의 Fabry-Perot 레이저를 이용하여 광펄스들을 생성하고, 광섬유를 통해 전송되는 광펄스들 사이의 군속도 차(group delay difference)를 Fabry-Perot 레이저의 자기궤환 발진 현상을 통해 감지함으로써 광섬유의 색분산계수를 측정할 수 있도록 하였다. 제안된 측정법에 따라 구현된 측정 장치는 고가의 상용 계측기와 비슷한 수준의 색분산계수 측정 정확도를 제공하고, 재현성은 0.5%보다 좋음을 실험적으로 검증하였다.

• Journal of the Optical Society of Korea
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• 제13권2호
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• pp.245-250
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• 2009

We propose a digital holographic interference analysis method based on a 2-frame phase-shifting technique for measuring an optical mirror surface. The technique using 2-frame phase-shifting digital interferometry is more efficient than multi-frame phase-shifting techniques because the 2-frame method has the advantage of a reduced number of interferograms, and then takes less time to acquire the wanted topography information from interferograms. In this measurement system, 2-frame phase-shifting digital interferograms are acquired by moving the reference flat mirror surface, which is attached to a piezoelectric transducer, with phase step of 0 or $\pi$/2 in the reference beam path. The measurements are recorded on a CCD detector. The optical interferometry is designed on the basis of polarization characteristics of a polarizing beam splitter. Therefore the noise from outside turbulence can be decreased. The proposed 2-frame algorithm uses the relative phase difference of the neighbor pixels. The experiment has been carried out on an optical mirror which flatness is less than $\lambda$/4. The measurement of the optical mirror surface topography using 2-frame phase-shifting interferometry shows that the peak-to-peak value is calculated to be about $0.1779{\mu}m$, the root-mean-square value is about $0.034{\mu}m$. Thus, the proposed method is expected to be used in nondestructive testing of optical components.

• 센서학회지
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• 제10권1호
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• pp.9-15
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• 2001

외인성 패브리-페롯 간섭계(EFPI) 광섬유 센서는 민감도와 분해능이 우수하며, 다른 종류의 광섬유 센서에 비해 많은 장점을 가지고 있다. 하지만 EFPI 광섬유 센서는 단지 프린지 개수만을 계산하여 측정량을 얻기 때문에 측정 방향을 구별하기 어렵다. 본 논문에서는 측정방향의 구분을 위한 추가적인 기능과 기존의 EFPI 광섬유 센서와는 다른 측정 시스템을 갖는 투과형 외인성 패브리-페롯 간섭계(TEFPI) 광섬유 센서를 개발하였다. 그리고 이를 이용하여 변형률 및 온도를 측정하였다.