• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.1
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• pp.1-12
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• 1997

The acousto-optical spectrometer as a new type backend of the receiver system for radio astronomical observations is manufactured for radio signal analysis. We studied on the effect of Acousto-Optic and Acousto-Optic devices and designed the optics system. We manufactured the optical mount and the CCD detector for deflected beam and interface card. This acousto-optical spectrometer consisted of a laser, optics, acousto-optic deflector, CCD detector and Interface card. This system use He-Ne laser as a light source and use optics to get parallel beam and to focus the deflected beam. Acousto-optic deflector converts IF signal to ultrasonic wave and deflect the laser beam according to the Bragg deflection. The ultra wide band acousto-optic deflector has 1 GHz bandwidth and a total of 2,048 channel Charge Coupled Device for signal detection. In this study, we discuss the theoretical description on the effect of Acousto-optics, the design of the optics, manufacture of optical mount, CCD detector, interface card and we presented the results of experiment. As a result of measurement, we have 1,000 channels bandwidth from CCD channels.

• Korean Journal of Optics and Photonics
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• v.35 no.2
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• pp.61-70
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• 2024

We demonstrate a laser power meter calibration system based on 12-diode laser sources coupled to single-mode fibres in a wavelength range from 400 to 1,600 nm. In our system, three laser power controllers ensure that the output power uncertainty of all laser sources is less than 0.1% (k=2). In addition, all laser beams are adjusted to have similar beam sizes of approximately 2 mm (1/e²-width) at the measurement position to minimise unmeasured laser power on a detector. As a reference detector, we use an integrating sphere combined with silicon and indium gallium arsenide photodiodes to minimise the non-uniformity and non-linearity of responsivity. The minimum uncertainty of the calibration system is estimated to be 1.1% (k=2) for most laser wavelengths.

• Korean Journal of Optics and Photonics
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• v.26 no.1
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• pp.9-16
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• 2015

We have developed ellipsometry lidar and measured aerosol and ice-cloud characteristics. To measure a full normalized backscattering phase matrix (NBSPM) composed of nine elements, we have designed an optical system with three kinds of transmission and three kinds of reception, composed of ${\lambda}/2$ waveplate, ${\lambda}/4$ waveplate and empty optic. To find systematic optical errors, we used clean day middle-altitude (4-6km) lidar signals for which the aerosol's concentration was small and its orientation chaotic. After calibrating our lidar system, we have calculated NBSPM elements scattered from an aerosol and from an ice cloud. In the case of an aerosol, we found that the off-diagonal values $m_{12},{\ldots},m_{34}$ of the NBSPM are smaller than those for a cirrus cloud. Also, the off-diagonal values of the NBSPM from a cirrus cloud depend on atmospheric conditions.

• Korean Journal of Optics and Photonics
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• v.12 no.6
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• pp.468-471
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• 2001

A novel method to measure the cell gap of a single-polarizer reflective twisted nematic liquid crystal (TN LC) cell by using a rotating polarizer technique is proposed. By rotating an LC cell, we can measure the cell gap of an LC cell as well as the wavelength dependence of retardation under the condition that the twist angle is known.

• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.148-149
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• 2000

파장분할다중(WDM) 광통신시스템에서 광원의 파장을 정확하게 측정하는 것은 매우 중요하다. 지금까지 광파장측정기는 격자나 Fabry-Perot 에탈론을 사용한 광대역 필터(optical bandpass filter) 및 파장에 따라 삽입손실이 다른 파장판별기(wavelength discriminator)등으로 구현되었지만 빛의 간섭 현상을 이용한 마이켈슨 간섭계가 가장 많이 사용되었다. 특히 푸리에 변환 마이켈슨 간섭계 파장측정기$^{(1)}$ 는 동시에 각각 다른 파장의 광원들이 입사되더라도 각각의 파장을 측정할 수 있는 장점이 있다. 즉 마이켈슨 간섭계에서 주기적인 간섭무늬에 의한 광검출기의 출력은 입력된 광파장에 따라 다른 주기를 가진다. 따라서 서로 다른 파장을 가진 빛이 입사했을 때 검출되는 각각의 광전력의 합을 표본화(sampling)한 뒤 FFT를 거치면 광파장과 광검출기로 수신한 신호의 중심 주파수의 관계를 알 수 있으므로, 서로 다른 파장을 가진 빛이 입사하더라도 각각의 파장을 측정할 수 있는 것이다. 본 논문에서는 푸리에 변환을 이용하되 마이켈슨 간섭계 대신 마하젠더 간섭계형 광변조기를 이용하여 광파장을 측정에 관한 실험적 구현과 개선 방안에 대해 제시한다. (중략)

• Korean Journal of Optics and Photonics
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• v.32 no.5
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• pp.215-219
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• 2021

Recently a system for nondestructive measurement of seedling plants in real time has been attracting attention as an essential element in fields such as the "smart farm". This study reports the simultaneous measurement of anthocyanin accumulations in leaf tissues in a large number of bok choy, using a hyperspectral imaging system. To measure many seedlings simultaneously, an existing hyperspectral imaging system is modified. In this paper, a total of 96 seedlings are measured: 24 each of 4 cultivars. Using the hyperspectral data-acquisition system, 12 seedlings can be analyzed simultaneously within 3 minutes. The hyperspectral imaging technology proposed in this paper is shown to provide an analytic system comparable to destructive chemical analysis. This hyperspectral imaging technology can be applied to a high-throughput plant-phenotyping system, owing to its capability of measuring a large number of specimens at the same time.

• Korean Journal of Optics and Photonics
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• v.14 no.3
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• pp.260-265
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• 2003

A noncontact optical system that can measure displacement or vibration of an object is designed by employing the oblique ray method. By using a single convex lens which serves as both the input and output lenses, we made the optical system very compact and reliable. In addition, the bandwidth of the vibration measurement is more than 100 KHz by using the position-sensitive detector as the beam position sensor. The resolution and capture range of the system are $\pm$1 ${\mu}{\textrm}{m}$ and 1100 ${\mu}{\textrm}{m}$, respectively. As a sample test, the vibrations of a speaker and a rotating compact disc surface were measured.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.1
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• pp.41-48
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• 2019

This paper deals with a method of aligning an aircraft fuselage and an inertial navigation sensor using three-dimensional coordinates obtained by an optical method. In order to verify the feasibility, we introduce the method to accurately align the coordinate system of the inertial navigation sensor and the aircraft reference coordinate system. It is verified through simulation that reflects the error level of the measuring device. In addition, optimization method based alignment algorithm is proposed for connection between optical sensor and inertial navigation sensor.

• Journal of Astronomy and Space Sciences
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• v.24 no.1
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• pp.79-90
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• 2007

The AmonRa instrument, the primary payload of the international EARTHSHINE mission, is designed for measurement of deep space albedo from L1 halo orbit. We report the optical design, tolerance analysis and the optical performance of the breadborad AmonRa imaging channel instrument optimized for the mission science requirements. In particular, an advanced wavefront feedback process control technique was used for the instrumentation process including part fabrication, system alignment and integration. The measured performances for the complete breadboard system are the RMS 0.091 wave(test wavelength: 632.8 nm) in wavefront error, the ensquared energy of 61.7%($in\;14\;{\mu}m$) and the MTF of 35.3%(Nyquist frequency: $35.7\;mm^{-1}$) at the center field. These resulting optical system performances prove that the breadboard AmonRa instrument, as built, satisfies the science requirements of the EARTHSHINE mission.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.149.1-149.1
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• 2014

전자총의 방출전류량과 소스크기, 그리고 방출 각전류밀도(angular current density)를 측정함으로서 얻어지는 전자총의 휘도(brightness)는 대물렌즈의 수차와 더불어 전자현미경의 성능을 좌우한다. 국내업체의 전자현미경은 대부분 상대적으로 휘도가 낮지만 작동압력이 10-5 Torr의 이하여서 제작과 사용이 용이한 텅스텐 필라멘트 열전자총을 채용하고 있다. 주사전자현미경의 성능을 좌우하는 프로브 크기와 전류량은 광학계의 배율과 전자총의 휘도에 의해서 결정되며, 설계시 전자현미경의 사양을 결정하기 위해서는 전자총의 휘도 측정이 필수이다. 한국표준과학연구원에서는 국내에서 생산되는 전자현미경용 열전자총의 휘도를 측정하기 위해, 전자총의 방출 각전류밀도와 소스 크기를 측정할 수 있는 전자총 휘도 측정 시스템을 개발하고 있다. 본 발표에서는 개발중인 시스템의 측정 원리를 기술한다. 또한 외부 자기장에 의한 교란을 방지하기 위해 연자성 재료인 연강으로 제작한 진공챔버의 진공특성을 보고한다.