• Title, Summary, Keyword: instrumentation: infrared

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CURRENT STATUS OF THE INSTRUMENTS, INSTRUMENTATION AND OPEN USE OF OKAYAMA ASTROPHYSICAL OBSERVATORY

  • YOSHIDA MICHITOSHI
    • Journal of The Korean Astronomical Society
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    • v.38 no.2
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    • pp.117-120
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    • 2005
  • Current instrumentation activities and the open user status of Okayama Astrophysical Observatory (OAO) are reviewed. There are two telescopes in operation and one telescope under reforming at OAO. The 188cm telescope is provided for open use for more than 200 nights in a year. The typical over-subscription rate of observation proposals for the 188cm telescope is ${\~}$ 1.5 - 2. The 50cm telescope is dedicated to $\gamma$-ray burst optical follow-up observation and is operated in collaboration with Tokyo Institute of Technology. The 91cm telescope will become a new very wide field near-infrared camera in two years. The high-dispersion echelle spectrograph (HIDES) is the current primary instrument for the open use of the 188cm telescope. Two new instruments, an infrared multi-purpose camera (ISLE) and an optical low-dispersion spectrograph (KOOLS), are now under development. They will be open as common use instruments in 2006.

Fabrication and Characteristics of Pyroelectric Infrared Sensor Using $PbTiO_3$/P(VDF/TrFE) Nanocomposites Thin Film (ICCAS 2004)

  • Kwon, Sung-Yeol;Bae, Jong-Il;Jo, Bong-Kwan;Kim, Do;Ahn, Doo-Sung
    • 제어로봇시스템학회:학술대회논문집
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    • pp.2041-2044
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    • 2004
  • A pyroelectric sensor using $PbTiO_3$/P(VDF/TrFE) nanocomposites thin film for sensing materials has been fabricated and evaluated with other commercial pyroelectric sensors that use ceramic materials for sensing. The device was mounted in a TO-5 housing to detect infrared light of 5.5 ~ 14 ${\mu}m$ wavelength. The NEP (noise equivalent power) and specific detectivity D of the device were 1.30 ${\times}$ $10^{-8}$W and 1.53 ${\times}$ $10^7$cm /W respectively under emission energy of 13 ${\mu}$W/c$m^2$ respectively. This result shows a better characteristic than the other commercial pyroelectric infrared sensors.

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Thermal Characterization of Individual Pixels in Microbolometer Image Sensors by Thermoreflectance Microscopy

  • Ryu, Seon Young;Choi, Hae Young;Kim, Dong Uk;Kim, Geon Hee;Kim, Taehyun;Kim, Hee Yeoun;Chang, Ki Soo
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.15 no.5
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    • pp.533-538
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    • 2015
  • Thermal characterization of individual pixels in microbolometer infrared image sensors is needed for optimal design and improved performance. In this work, we used thermoreflectance microscopy on uncooled microbolometer image sensors to investigate the thermal characteristics of individual pixels. Two types of microbolometer image sensors with a shared-anchor structure were fabricated and thermally characterized at various biases and vacuum levels by measuring the temperature distribution on the surface of the microbolometers. The results show that thermoreflectance microscopy can be a useful thermal characterization tool for microbolometer image sensors.

Responsivity and Noise Evaluation of Infrared Thermal Imaging Camera (적외선열화상카메라의 응답 및 노이즈 특성 평가)

  • Kim, Dong-Ik;Kim, Ghiseok;Kim, Geon-Hee;Chang, Ki Soo
    • Journal of the Korean Society for Nondestructive Testing
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    • v.33 no.4
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    • pp.342-348
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    • 2013
  • In this paper, the evaluation method for the responsivity and noise characteristics of an infrared thermal imaging camera was presented. Signal transfer function and noise equivalent temperature difference of the infrared thermal imaging camera were obtained by using a differential mode blackbody that is able to control the temperature difference ${\Delta}$T between an infrared target and its background. And we verified the suitability of our evaluation method through comparison between the found noise equivalent temperature difference and the specification of the camera. In addition, the difference of 0.01 K of the two noise equivalent temperature differences calculated from with and without nonuniformity correction suggests that the nonuniformity correction is essential process for the evaluation of the infrared thermal imaging camera.

Design and Performance Evaluation of Low-Temperature Vacuum Blackbody System (저온-진공 흑체시스템의 설계 및 성능 평가)

  • Kim, Ghiseok;Chang, Ki Soo;Lee, Sang-Yong;Kim, Geon-Hee;Kim, Dong-Ik
    • Journal of the Korean Society for Nondestructive Testing
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    • v.33 no.4
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    • pp.336-341
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    • 2013
  • In this paper, the design concept of a low-temperature vacuum blackbody was described, and thermophysical model of the blackbody was numerically evaluated. Also the working performance of low-temperature vacuum blackbody was evaluated using infrared camera system. The blackbody system was constructed to operate under high-vacuum conditions ($2.67{\times}10^{-2}$ Pa) to reduce temperature uncertainty, which is caused by vapor condensation at low temperatures usually below 273 K. In addition, both heat sink and heat shield including cold shield were installed around radiator to prevent heat loss from the blackbody. Simplified mathematical model of blackbody radiator was analyzed using modified Stefan-Boltzmann's rule. The infrared radiant performance of the blackbody was evaluated using infrared camera. Based on the results of measurements, and simulation, temperature stability of the low-temperature vacuum blackbody demonstrated that the blackbody system can serve as a highly stable reference source for the calibration of an infrared optical system.

Temperature Dependency of Non-dispersive Infrared Carbon Dioxide Gas Sensor by Using White-Cell Structure (White-Cell 구조를 응용한 비분산 적외선 이산화탄소 센서의 온도특성)

  • Yi, SeungHwan;Park, YoungHwan;Lee, JaeKyung
    • Journal of Sensor Science and Technology
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    • v.25 no.5
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    • pp.377-381
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    • 2016
  • NDIR $CO_2$ gas sensor was prototyped with ASIC implemented thermopile sensor which included temperature sensor and White-Cell structure in this paper. The temperature dependency of dual infrared sensors ($CO_2$ and reference IR sensors) has been characterized and their output voltage ratios according to the temperature and gas concentration were presented in this paper for achieving temperature compensation algorithm. The initial output voltages of NDIR $CO_2$ gas and reference IR sensors showed $3^{rd}$ order polynomial and linear output voltages according to the variation of ambient temperatures from 253 K to 333 K, respectively. The output voltages of temperature sensor presented a linear dependency according to the ambient temperature and could be described with V(T) = -3.0069+0.0145T(V). The characteristics of output voltage ratios could be modeled with five parameters which are dependent upon the ambient temperatures and gas concentration. The estimated $CO_2$ concentrations showed relatively high error below 300 ppm (maximum 572 % at 7 ppm $CO_2$ concentration), however, as the concentration increased from 500 ppm to 2,000 ppm, the overall estimated errors of $CO_2$ concentrations were less than ${\pm}10%$ in this research.

Signal Processing for Stabilizing Output of Fine Dust Sensor (미세먼지 센서 출력의 안정화를 위한 신호처리)

  • Jung, Sang-Wook;Park, Jun-Hyeon;Kim, Ju-An;Kim, Jae-Wook;Cheon, Bong-Won;Kim, Nam-Ho
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.344-346
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    • 2018
  • Air pollution has become a social issue. Particularly, interest in fine dust is increasing. Various kinds of sensors are being used to measure fine dust. The most commonly used infrared detection dust sensors operate by sensing the diffraction of light through an infrared receiver and sensing the light reflected by the dust in the air. However, this method has a drawback in which accurate data analysis is difficult due to deviation caused by the noise during measurement. In order to overcome such drawbacks, in this thesis, a low pass filter algorithm of FIR(Finite Impulse Response) filter was designed and implemented.

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Fabrication of Freeform Aluminum mirrors for Wide Field Infrared Telescopes

  • Jeong, Byeongjoon;Gwak, Jeongha;Pak, Soojong;Kim, Geon Hee;Lee, Kwang Jo;Park, Junbeom;Lee, Hye-In;Park, Woojin;Ji, Tae-Geun
    • The Bulletin of The Korean Astronomical Society
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    • v.42 no.1
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    • pp.57.3-58
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    • 2017
  • Single Point Diamond Turning (SPDT) is a cost-effective technique to fabricate metallic mirrors. In particular, the servo-assisted diamond turning option is highly useful for the fabrication of freeform surfaces. However, the SPDT process leaves periodic tool marks on machined mirror surfaces, leading to undesirable diffraction effect, as well as the deviation of input beam. In order to solve this problem, we propose new SPDT machining conditions to minimize tool marks. We will also show the results from optical measurement and Power Spectral Density (PSD) analysis to evaluate the expectable performance for applications in wide field infrared telescopes.

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NDE of Low-Velocity Impact Damage in GFRP Using Infrared Thermography Techniques

  • Kim, Ghiseok;Lee, Kye-Sung;Hur, Hwan;Kim, Sun-Jin;Kim, Geon-Hee
    • Journal of the Korean Society for Nondestructive Testing
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    • v.35 no.3
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    • pp.206-214
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    • 2015
  • In this study, low-velocity impact damage (LVID) in glass fiber reinforced plastic (GFRP) was investigated using pulse thermography (PT) and lock-in thermography (LIT) techniques. The main objective of this study was to evaluate the detection performance of each technique for LVID in GFRP. Unidirectional and cross-ply GFRPs were prepared with four energy levels using a drop weight impact machine and they were inspected from the impact side, which may be common in actual service conditions. When the impacted side was used for both inspection and thermal loading, results showed that the suggested techniques were able to identify the LVID which is barely visible to the naked eye. However, they also include limitations that depend on the GFRP thickness at the location of the delamination produced by the lowest impact energy of five joule.