• 천문학논총
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• 제32권1호
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• pp.83-85
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• 2017

We conducted an unbiased near- to mid-infrared imaging and spectroscopic survey of the Large Magellanic Cloud (LMC) as a part of the AKARI Mission Program "Large-area Survey of the LMC" (LSLMC, PI: T. Onaka). An area of about 10 square degrees of the LMC was observed by five photometric bands (3.2, 7, 11, 15, and $24{\mu}m$) and a low-resolution slitless prism ($2-5{\mu}m$, R ~20) equipped with AKARI /IRC. We constructed and publicly released photometric and spectroscopic catalogues of point sources in the LMC based on the survey data. The catalogues provide a large number of near-infrared spectral data, coupled with complementary broadband photometric data. Combined use of the present AKARI LSLMC catalogues with other infrared point source catalogues of the LMC possesses scientific potential that can be applied to various astronomical studies.

• 한국산업융합학회 논문집
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• 제26권6_2호
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• pp.1073-1082
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• 2023

Thermal sensors, also called thermal infrared wavelength sensors, measure temperature based on the intensity of infrared signals that reach the sensor. The infrared signals recognized by the sensor include infrared wavelength(0.7~3.0㎛) and radiant infrared wavelength(3.0~100㎛). Infrared(IR) wavelengths are divided into five bands: near infrared(NIR), shortwave infrared(SWIR), midwave infrared(MWIR), longwave infrared(LWIR), and far infrared(FIR). Most thermal sensors use the LWIR to capture images. Thermal sensors measure the temperature of the target in a non-contact manner, and the data can be affected by the sensor's viewing angle between the target and the sensor, the amount of atmospheric water vapor (humidity), air temperature, and ground conditions. In this study, the characteristics of three thermal imaging sensor models that are widely used for observation using unmanned aerial vehicles were evaluated, and the optimal application field was determined.

• 한국광학회지
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• 제34권3호
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• pp.106-116
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• 2023

본 논문에서는 가시광선과 원적외선 전반의 파장대역에 걸쳐 사용 가능한 동축 듀얼카메라를 설계 및 분석하였다. 광학계는 빔 스플리터를 이용한 동축광학계 시스템으로 설계되었으며, 가시광선 광학계에서 적외선으로 인한 열 전달을 최소화하기 위해 hot mirror 타입의 빔 스플리터를 사용하였다. 원적외선 카메라는 비냉각형 검출기로 640×480의 센서 배열을 가지고, 가시광선은 1,945×1,097의 센서를 사용한다. 최적화 과정을 거친 후 최종 설계된 광학계의 정합도는 90% 이상이며, 기존에 존재하던 듀얼카메라에 비해 정합도가 향상된 효율적인 설계 결과를 얻었고, 테스트를 통해 향상된 정합도를 확인하였다.

• 한국기계가공학회지
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• 제16권4호
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• pp.140-146
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• 2017

As energy conservation and environmental issues are emerging as a hot topic around the world, consumers are demanding high-efficiency, eco-friendly products. In this study, the author proposed 120W LED lighting system that replace metal halide lamp (MHL) which is currently used in the industry. Furthermore, it would be possible to provide a perfect opportunity for Korea to rise as a global leader in the LED lighting industry through soundness evaluation of the LED lighting system that is applied.

• Current Optics and Photonics
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• 제6권2호
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• pp.151-160
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• 2022

Fundus images can reflect ocular diseases and systemic diseases such as glaucoma, diabetes mellitus, and hypertension. Thus, research on fundus-detection equipment is of great importance. The fundus camera has been widely used as a kind of noninvasive detection equipment. Most existing devices can only obtain two-dimensional (2D) retinal-image information, yet the fundus of the human eye also has spectral characteristics. The fundus has many pigments, and their different distributions in the eye lead to dissimilar tissue penetration for light waves, which can reflect the corresponding fundus structure. To obtain more abundant information and improve the detection level of equipment, a snapshot nonmydriatic fundus imaging spectral system, including fundus-imaging spectrometer and illumination system, is studied in this paper. The system uses a microlens array to realize snapshot technology; information can be obtained from only a single exposure. The system does not need to dilate the pupil. Hence, the operation is simple, which reduces its influence on the detected object. The system works in the visible and near-infrared bands (550-800 nm), with a volume less than 400 mm × 120 mm × 75 mm and a spectral resolution better than 6 nm.

• 한국근적외분광분석학회:학술대회논문집
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• 한국근적외분광분석학회 2001년도 NIR-2001
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• pp.1526-1526
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• 2001

To improve the accuracy of sweetness sensor in automated sorting operations, it is necessary to clarify unevenness of the sugar content distribution within fruits. And it is expected that the technique to evaluate the content distribution in fruits contribute to the development of the near-infrared (NIR) imaging spectroscopy. Sugiyama (1999) had succeeded to visualize the distribution of the sugar content on the surface of a half-cut green fresh melon. However, this method cannot be applied to red flesh melons because it depends on information of the absorption band of chlorophyll (676 nm), which is affected by the color of the fresh. The objective of this study was to develop the universal visualization method depends on the absorption band of sugar, which can be applied to various kinds of melons and other fruits. The relationship between the sugar contents and absorption spectra of both green and red fresh melons were investigated by using a NIR spectrometer to determine the absorption band of sugar. The combination of 2$\^$nd/ derivative absorbances at 902 nm and 874 nm was highly correlated with the sugar contents. The wavelength of 902 nm is attributed to the absorption band of sugar. A cooled charge-coupled device (CCD) imaging camera which has 16 bit (65536 steps) A/D resolution was equipped with rotating band-pass filter wheel and used to capture the spectral absorption images of the flesh of a vertically half-cut red fresh melon. The advantage of the high A/D resolution in this research is that each pixel of the CCD is expected to function as a detector of the NIR spectrometer for quantitative analysis. Images at 846 nm, 874 nm, 902 nm and 930 nm were acquired using this CCD camera. Then the 2$\^$nd/ derivative absorbances at 902 nm and 874 nm at each pixel were calculated using these four images. On the other hand, parts of the same melon were extracted for capturing the images and squeezed for the measurement of sugar content. Then the calibration curve between the combination of 2$\^$nd/ derivative absorbances at 902 nm and 874 nm and sugar content was developed. The calibration method based on NIR spectroscopy techniques was applied to each pixel of the images to convert the 2$\^$nd/ derivative absorbances into the Brix sugar content. Mapping the sugar content value of each pixel with linear color scale, the distribution of the sugar content was visualized. As a result of the visualization, it was quantitatively confirmed that the Brix sugar contents are low at the near of the skin and become higher towards the seeds. This result suggests that the visualization technique by the NIR imaging spectroscopy could become a new useful method fer quality evaluation of melons.

• Journal of Astronomy and Space Sciences
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• 제29권3호
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• pp.305-313
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• 2012

We conducted thermal analyses and cooling tests of the space observation camera (SOC) of the multi-purpose infrared imaging system (MIRIS) to verify passive cooling. The thermal analyses were conducted with NX 7.0 TMG for two cases of attitude of the MIRIS: for the worst hot case and normal case. Through the thermal analyses of the flight model, it was found that even in the worst case the telescope could be cooled to less than $206^{\circ}K$. This is similar to the results of the passive cooling test (${\sim}200.2^{\circ}K$). For the normal attitude case of the analysis, on the other hand, the SOC telescope was cooled to about $160^{\circ}K$ in 10 days. Based on the results of these analyses and the test, it was determined that the telescope of the MIRIS SOC could be successfully cooled to below $200^{\circ}K$ with passive cooling. The SOC is, therefore, expected to have optimal performance under cooled conditions in orbit.

• 천문학논총
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• 제21권2호
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• pp.43-49
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• 2006

The KASINICS (KASI Near Infrared Camera System) is a ground-based Near-Infrared (NIR) imaging instrument developed by the Korea Astronomy and Space Science Institute (KASI). In this paper, we report the test results of the KASINICS camera optics system which is comprised of a 1-1 Offner relay. We measure that the surface RMS fluctuations of the Offner mirrors are at the level of $10^{-1}-10^{-2}$ of the target wavelengths, showing that the mirrors are sufficiently smooth for NIR observations. The alignment of the Offner optics system has been checked too. Our ray-tracing simulations find that the image quality should not degrade more than the pixel size of the KASINICS ($40{\mu}m$), if a de-centering or a tilt of the Offner mirrors are within 5mm, or $2.5^{\circ}$. Our measurement shows that the de-centering or the tilt of the Offner mirrors are less than 1 mm or $0.5^{\circ}$, assuring that the KASINICS image quality are not affected by the alignment errors. We have also measured that the optics resolution is $20{\mu}m$ and it does not degrade more than 10% over the detector surface area of 14.3 mm ${/times}$ 14.3mm. Overall, we conclude that the KASINICS optics system satisfies the design requirements for NIR imaging observations.

• 한국산학기술학회논문지
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• 제1권2호
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• pp.27-31
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• 2000

대상 물체의 온도분포를 해석하고 계측하기 위해 열상 장비가 구현된다. 시스템의 주요한 부분은 초점면 배열 형태의 센서가 적용된 열상 카메라이다. 적용된 열상 센서는 중파장 적외선 영역의 신호를 검출하며 열상을 형성하기 위한 기본 신호를 출력한다. DSP가 활용되어 센서 신호처리를 통해 열상을 구성하고 NTSC 신호 및 디지털 신호 출력을 한다. 열상의 화질을 개선하기 위해 이점 교정법을 적용한다. 이는 낮은 온도와 높은 온도를 기준으로 하여 초점면 배열 센서 화소 신호의 공간적인 비균일함을 교정하는 것으로서 실험 결과를 통해 열상의 화질이 개선됨을 보인다.

• 한국정밀공학회지
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• 제27권12호
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• pp.15-21
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• 2010

Recently, there is a demand for a thermal imaging microscope in the medical field as well as the semi-conductor industry Although the demand of the advanced thermal imaging microscope has been increased, it is very difficult to obtain the technology of developing a thermal camera, because it is used for defense industry. We developed the ${\times}5$ zoom microscope which has $3\;{\mu}m$ spatial resolution to research the design and fabrication of the IR (Infrared) optical system. The optical system of the IR microscope consists of four spherical lenses and four aspheric lenses. We verified individual sensitivity of each optical parameter as the first order approach to the analysis. And we also performed structure and vibration analysis. The optical elements are fabricated using Freeform 700A. The measurement results of surface roughness and form accuracy using NT 2000 and UA3P are Ra 2.36 nm and P-V $0.13\;{\mu}m$. Finally we ascertained resolution power of $3\;{\mu}m$ using USAF (United State Air Force) 1951 IR resolution test chart.