• Current Optics and Photonics
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• v.5 no.2
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• pp.186-190
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• 2021

In this study, a compact, picosecond, mid-infrared 3.8 ㎛ MgO:PPLN optical parametric oscillator (OPO) laser output with high peak power is realized using a master oscillator power amplifier (MOPA) 1 ㎛ solid-state laser seeded by a picosecond fiber laser as the pump source. The pump source was a 50 MHz and 10 ps fiber seed source. After AOM pulse selection and two-stage solid-state amplification, a 1,064 nm laser output with a repetition frequency of 1-2 MHz, pulse width of 9.5 ps, and a maximum average power of 20 W was achieved. Furthermore, a compact short cavity with a unsynchronized pump is adopted through the design of an OPO cavity structure. When the injection pump power was 15 W and the repetition frequency was 1 MHz, the average output power of idler light was 1.19 W, and the corresponding peak power was 119 kW. The optical conversion efficiency was 7.93%. When the repetition frequency was increased to 2 MHz, the average output power of idler light was 1.63 W, the corresponding peak power was 81.5 kW, and the optical conversion efficiency was 10.87%. At the same time, the output wavelength was measured at 3,806 nm, and the beam quality was MX2 = 3.21 and MY2 = 3.34.

• Journal of the Korean Physical Society
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• v.73 no.12
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• pp.1821-1826
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• 2018

Uniformity is a key feature of state-of-the-art infrared focal planed array (IRFPA) and infrared imaging system. Unlike traditional infrared telescope facility, a ground-based infrared radiant characteristics measurement system with an IRFPA not only provides a series of high signal-to-noise ratio (SNR) infrared image but also ensures the validity of radiant measurement data. Normally, a long integration time tends to produce a high SNR infrared image for infrared radiant characteristics radiometry system. In view of the variability of and uncertainty in the measured target's energy, the operation of switching the integration time and attenuators usually guarantees the guality of the infrared radiation measurement data obtainted during the infrared radiant characteristics radiometry process. Non-uniformity correction (NUC) coefficients in a given integration time are often applied to a specified integration time. If the integration time is switched, the SNR for the infrared imaging will degenerate rapidly. Considering the effect of the SNR for the infrared image and the infrared radiant characteristics radiometry above, we propose a-wide-dynamic-range NUC algorithm. In addition, this essasy derives and establishes the mathematical modal of the algorithm in detail. Then, we conduct verification experiments by using a ground-based MWIR(Mid-wave Infared) radiant characteristics radiometry system with an Ø400 mm aperture. The experimental results obtained using the proposed algorithm and the traditional algorithm for different integration time are compared. The statistical data shows that the average non-uniformity for the proposed algorithm decreased from 0.77% to 0.21% at 2.5 ms and from 1.33% to 0.26% at 5.5 ms. The testing results demonstrate that the usage of suggested algorithm can improve infrared imaging quality and radiation measurement accuracy.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.66.1-66.1
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• 2011

E+A galaxies are interpreted as post-starburst systems because of strong Balmer absorption lines but any emission lines indicating the lack of current star formation activities, thus they are one of key populations for understanding how star formation activities evolve in galaxies. We present mid-infrared (MIR) spectral energy distributions of E+A galaxies using the Wide-field Infrared Survey Explorer (WISE) preliminary released data. Furthermore, we investigate the role of environment with respect to the MIR properties of E+A galaxies.

• Publications of The Korean Astronomical Society
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• v.32 no.1
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• pp.337-341
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• 2017

This paper reviews the requirements for far-infrared astronomy in the period following the SPICA satellite in the late 2020's. We take a very long view of the state of FIR astronomy and what facilities will be required in a twenty year timeframe. We show that spatial resolution to match that of observatories operating in the optical and mid-infrared and the radio will be a necessity. Moreover this high spatial resolution must be combined with high spectral and photometric sensitivity to provide the data required to further our understanding of planetary formation mechanisms, the history of star formation through cosmic time and the feedback between active galactic nuclei and their host galaxies in controlling star formation. We review three possible conceptual mission scenarios and comment on the possibility of realising them in the coming deades.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1628-1628
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• 2001

Near infrared (NIR) spectroscopy is a powerful technique for non-destructive analysis that can be obtained in a wide range of environments. Recently, NIR measurements have been utilized as probe for quantitative analysis in agricultural, industrial, and medical sciences. In addition, it is also possible to make practical application on NIR for molecular structural analysis. In this work, Fourier transform near infrared (FT-NIR) measurements were carried out to utilize extensively in the relative amounts of different secondary structures were employed, such as Iysozyme, concanavalin A, silk fibroin and so on. Several broad NIR bands due to the protein absorption were observed between 4000 and $5000\;^{-1}$. In order to obtain more structural information from these featureless bands, second derivative and Fourier-self-deconvolution procedures were performed. Significant band separation was observed near the feature at $4610\;^{-1}$ ,. Particularly the peak intensity at $4525\;^{-1}$ shows a characteristic change with thermal denaturation of fibroin. The structural information can be also obtained by mid-IR and CD spectral. Correlation of NIR spectra with protein structure is discussed.

• Journal of Korea Multimedia Society
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• v.21 no.12
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• pp.1379-1386
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• 2018

In this paper, we proposed eyeglass type periorbital wrinkle treatment device for reducing and improving periorbital wrinkles using near infrared LED of 850nm wavelength and galvanic current. The proposed periorbital wrinkle treatment device is equipped with a control system based on F-PCB. It consists of eight near-infrared LEDs and four indicator LEDs for treatment of right and left periorbital wrinkles. The eyeglass frame is coated with conductive material, so galvanic current can flow to the skin of periorbital wrinkle contacted to it. One male adult in the mid-40s was allowed to use the device for 10 minutes every day for 4 weeks. After 4 weeks, image analysis using optical equipment for measuring wrinkles indicated that wrinkle indexes were reduced.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1081-1081
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• 2001

The constant need for quality improvement and production rationalization in the chemical and related industries has led to the increasing replacement of conservative control procedures by more specific and environmentally compatible analytical techniques. In this respect, vibrational spectroscopy has developed over the last yews - in combination with new instrumental accessories and statistical evaluation procedures - to one of the most important analytical tools for industrial chemical quality control and process monitoring in a wide field of applications. In the present communication this potential is demonstrated in order to further support the implementation of mid-infrared (MIR), near-infrared (NIR) and Raman spectroscopy Primarily as industrial on-line tools. To this end the data of selected feasibility studies will be discussed in terms of the individual strengths of the different techniques for the respective application.

• Journal of Korean Society for Geospatial Information Science
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• v.24 no.4
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• pp.105-113
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• 2016

Fire radiative power(FRP), which means the power radiated from wildfire, is used to estimate fire emissions. Currently, the geostationary satellites of East Asia do not provide official FRP products yet, whereas the American and European geostationary satellites are providing near-real-time FRP products for Europe, Africa and America. This paper describes the first retrieval of Himawari-8 FRP using the mid-infrared radiance method and shows the comparisons with MODIS FRP for Sumatra, Indonesia. Land surface emissivity, an essential parameter for mid-infrared radiance method, was calculated using NDVI(normalized difference vegetation index) and FVC(fraction of vegetation coverage) according to land cover types. Also, the sensor coefficient for Himawari-8(a = 3.11) was derived through optimization experiments. The mean absolute percentage difference was about 20%, which can be interpreted as a favourable performance similar to the validation statistics of the American and European satellites. The retrieval accuracies of Himawari FRP were rarely influenced by land cover types or solar zenith angle, but parts of the pixels showed somewhat low accuracies according to the fire size and viewing zenith angle. This study will contribute to estimation of wildfire emissions and can be a reference for the FRP retrieval of current and forthcoming geostationary satellites in East Asia.

• Publications of The Korean Astronomical Society
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• v.27 no.4
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• pp.187-193
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• 2012

AKARI has 4 imaging bands in the far-infrared (FIR) and 9 imaging bands that cover the near-infrared (NIR) to mid-infrared (MIR) contiguously. The FIR bands probe the thermal emission from sub-micron dust grains, while the MIR bands observe emission from stochastically-heated very small grains and the unidentified infrared (UIR) band emissions from carbonaceous materials that contain aromatic and aliphatic bonds. The multi-band characteristics of the AKARI instruments are quite efficient to study the spectral energy distribution of the interstellar medium, which always shows multi-component nature, as well as its variations in the various environments. AKARI also has spectroscopic capabilities. In particular, one of the onboard instruments, Infrared Camera (IRC), can obtain a continuous spectrum from 2.5 to $13{\mu}m$ with the same slit. This allows us to make a comparative study of the UIR bands in the diffuse emission from the 3.3 to $11.3{\mu}m$ for the first time. The IRC explores high-sensitivity spectroscopy in the NIR, which enables the study of interstellar ices and the UIR band emission at $3.3-3.5{\mu}m$ in various objects. Particularly, the UIR bands in this spectral range contain unique information on the aromatic and aliphatic bonds in the band carriers. This presentation reviews the results of AKARI observations of the interstellar medium with an emphasis on the observations of the NIR spectroscopy.

• Journal of the Korean Society for Precision Engineering
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• v.34 no.3
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• pp.199-203
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• 2017

Hot embossing techniques are used to engrave patterns on plastic substrates. Roll based hot embossing uses a heated roll for a continuous process. A heated roll with relief patterns is impressed on a preheated plastic substrate. Then, the substrate is cooled down quickly to prevent thermal shrinkage. The roll speed is normally very slow to ensure substrate temperature increase up to the glass transition temperature. In this paper, we propose a noncontact preheating technique using focused infrared light. The infrared light is focused as a line beam on a plastic substrate using an elliptical mirror just before entering the hot embossing roll. The mid range infrared light efficiently raises the substrate temperature. For preliminary tests, substrate deformation and temperature changes were monitored according to substrate speed. The experiments show that the proposed technique is a good possibility for high speed hot embossing.