• Title/Summary/Keyword: Near-infrared Light

Search Result 256, Processing Time 0.028 seconds

Recent Progress in Luminescent Lanthanide Complexes for Advanced Photonics Applications

  • Kim, Hwan-Kyu;Oh, Jae-Buem;Baek, Nam-Seob;Roh, Soo-Gyun;Nah, Min-Kook;Kim, Yong-Hee
    • Bulletin of the Korean Chemical Society
    • /
    • v.26 no.2
    • /
    • pp.201-214
    • /
    • 2005
  • We have designed and developed novel luminescent lanthanide complexes for advanced photonics applications. Lanthanide(III) ions (Ln$^{3+}$) were encapsulated by the luminescent ligands such as metalloporphyrins and naphthalenes. The energy levels of the luminescent ligands were tailored to maintain the effective energy transfer process from luminescent ligands to Ln$^{3+}$ ions for getting a higher optical amplification gain. Also, key parameters for emission enhancement and efficient energy transfer pathways for the sensitization of Ln$^{3+}$ ions by luminescent ligands were investigated. Furthermore, to enhance the optophysical properties of novel luminescent Ln$^{3+}$ complexes, aryl ether-functionalized dendrons as photon antennas have been incorporated into luminescent Ln$^{3+}$ complexes, yielding novel Ln(III)-cored dendrimer complex. The novel Ln(III)-cored dendrimer complex has much higher PL intensity than the corresponding simple complex, due to the efficient site-isolation effect. In this article, we will deal with recent progress in the synthesis and photophysical studies of inert and stable luminescent Ln$^{3+}$ complexes for advanced photonics applications. Also, our review will include the exploratory investigation of the key parameters for emission enhancement and the effective energy transfer pathways from luminescent ligands to Ln$^{3+}$ ions with Ln(III)-chelated prototype complexes.

ADVANTAGES OF USING ARTIFICIAL NEURAL NETWORKS CALIBRATION TECHNIQUES TO NEAR-INFRARED AGRICULTURAL DATA

  • Buchmann, Nils-Bo;Ian A.Cowe
    • Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
    • /
    • 2001.06a
    • /
    • pp.1032-1032
    • /
    • 2001
  • Artificial Neural Network (ANN) calibration techniques have been used commercially for agricultural applications since the mid-nineties. Global models, based on transmission data from 850 to 1050 nm, are used routinely to measure protein and moisture in wheat and barley and also moisture in triticale, rye, and oats. These models are currently used commercially in approx. 15 countries throughout the world. Results concerning earlier European ANN models are being published elsewhere. Some of the findings from that study will be discussed here. ANN models have also been developed for coarsely ground samples of compound feed and feed ingredients, again measured in transmission mode from 850 to 1050 nm. The performance of models for pig- and poultry feed will be discussed briefly. These models were developed from a very large data set (more than 20,000 records), and cover a very broad range of finished products. The prediction curves are linear over the entire range for protein, fat moisture, fibre, and starch (measured only on poultry feed), and accuracy is in line with the performance of smaller models based on Partial Least Squares (PLS). A simple bias adjustment is sufficient for calibration transfer across instruments. Recently, we have investigated the possible use of ANN for a different type of NIR spectrometer, based on reflectance data from 1100 to 2500 nm. In one study, based on data for protein, fat, and moisture measured on unground compound feed samples, dedicated ANN models for specific product classes (cattle feed, pig feed, broiler feed, and layers feed) gave moderately better Standard Errors of Prediction (SEP) compared to modified PLS (MPLS). However, if the four product classes were combined into one general calibration model, the performance of the ANN model deteriorated only slightly compared to the class-specific models, while the SEP values for the MPLS predictions doubled. Brix value in molasses is a measure of sugar content. Even with a huge dataset, PLS models were not sufficiently accurate for commercial use. In contrast an ANN model based on the same data improved the accuracy considerably and straightened out non-linearity in the prediction plot. The work of Mr. David Funk (GIPSA, U. S. Department of Agriculture) who has studied the influence of various types of spectral distortions on ANN- and PLS models, thereby providing comparative information on the robustness of these models towards instrument differences, will be discussed. This study was based on data from different classes of North American wheat measured in transmission from 850 to 1050 nm. The distortions studied included the effect of absorbance offset pathlength variation, presence of stray light bandwidth, and wavelength stretch and offset (either individually or combined). It was shown that a global ANN model was much less sensitive to most perturbations than class-specific GIPSA PLS calibrations. It is concluded that ANN models based on large data sets offer substantial advantages over PLS models with respect to accuracy, range of materials that can be handled by a single calibration, stability, transferability, and sensitivity to perturbations.

  • PDF

A characteristics study on the Second-harmonic generation conversion efficiency of Pulsed Nd:YAG Laser adopted Superposition multiple Mesh Networks (중첩다단 메쉬회로를 적용한 펄스형 Nd:YAG 레이저의 2차 고조파 변환효율에 관한 특성연구)

  • 김휘영
    • Journal of the Korea Computer Industry Society
    • /
    • v.2 no.4
    • /
    • pp.565-572
    • /
    • 2001
  • At the most recent years, laser medical instruments, laser applications and laser nuclear fusion need strong visible light and ultraviolet rays. Nonlinear optical devices, such as harmonic generators and parametric oscillators, provide a means of extending the frequency range of available laser sources. Frequency conversion is a useful technique for extending the utility of high-power lasers. It utilizes the nonlinear optical response of an optical medium in intense radiation fields to generate new frequencies. These progresses have been used to generate high-power radiation in all spectral regions, from the ultraviolet to the far infrared. Optical parametric oscillators and amplifiers generate two waves of lower frequency They are capable of generating a range of wavelengths from a single frequency source, in some cases spanning the entire visible and near infrared regions. Consequently, in order to obtain the green light, the pulsed Nd:YAG laser using multiple-mesh PFN(Pulsed Forming Network) method with Nonlinear optical device was adopted. We compared the current pulseshapes with the laser output energy, and conversion efficiency.

  • PDF

miniTAO/ANIR Paα SURVEY OF LOCAL LIRGs

  • Tateuchi, Ken;Motohara, Kentaro;Konishi, Masahiro;Takahashi, Hidenori;Kato, Natsuko;Uchimoto, Yuka K.;Toshikawa, Koji;Ohsawa, Ryou;Kitagawa, Yutaro;Yoshii, Yuzuru;Doi, Mamoru;Kohno, Kotaro;Kawara, Kimiaki;Tanaka, Masuo;Miyata, Takashi;Tanabe, Toshihiko;Minezaki, Takeo;Sako, Shigeyuki;Morokuma, Tomoki;Tamura, Yoichi;Aoki, Tsutomu;Soyano, Takeo;Tarusawa, Kenfichi;Koshida, Shintaro;Kamizuka, Takafumi;Nakamura, Tomohiko;Asano, Kentaro;Uchiyama, Mizuho;Okada, Kazushi;Ita, Yoshifusa
    • Publications of The Korean Astronomical Society
    • /
    • v.27 no.4
    • /
    • pp.297-298
    • /
    • 2012
  • ANIR (Atacama Near InfraRed camera) is a near infrared camera for the University of Tokyo Atacama 1m telescope, installed at the summit of Co. Chajnantor (5,640 m altitude) in northern Chile. The high altitude and extremely low water vapor (PWV = 0.5 mm) of the site enable us to perform observation of hydrogen $Pa{\alpha}$ emission line at $1.8751{\mu}m$. Since its first light observation in June 2009, we have been carrying out a $Pa{\alpha}$ narrow-band imaging survey of nearby luminous infrared galaxies (LIRGs), and have obtained $Pa{\alpha}$ for 38 nearby LIRGs listed in AKARI/FIS-PSC at the velocity of recession between 2,800 km/s and 8,100 km/s. LIRGs are affected by a large amount of dust extinction ($A_V$~ 3 mag), produced by their active star formation activities. Because $Pa{\alpha}$ is the strongest hydrogen recombination line in the infrared wavelength ranges, it is a good and direct tracer of dust-enshrouded star forming regions, and enables us to probe the star formation activities in LIRGs. We find that LIRGs have two star-forming modes. The origin of the two modes probably come from differences between merging stage and/or star-forming process.

Development of a Real-time Grouping System of Rice Crop Canopy Chlorophyll Contents

  • Sung J.H.;Jung I.G.;Lee C.K.
    • Agricultural and Biosystems Engineering
    • /
    • v.6 no.1
    • /
    • pp.8-14
    • /
    • 2005
  • This study was carried out to develop a real-time grouping system of chlorophyll contents of rice crop canopy for precision agriculture. The system measured reflected light energy of a rice canopy on a paddy field from visual to near-infrared range and analyzed the collected information of chlorophyll contents of rice crop canopy with given position data. The four filters, 560 nm $({\pm}10nm)$, 650 nm $({\pm}25nm)$, 700 nm $({\pm}12nm)$, and 850 nm $({\pm}40nm)$, were used for a multiple regression to estimate the chlorophyll contents of rice crop canopy. Every $0.2m^2$ area of the open field was inspected at a distance of 1 m above the rice canopy. According to the results of verification test, the chlorophyll content grouping by a commerical chlorophyll meter (SPAD) and by the developed system showed 58.7% match for five-stage chlorophyll contents of rice crop canopy grouping and 93.5% for the $five{\pm}1-stage$ grouping. In addition, the results showed 63.0% match for three-stage grouping and 100.0% for the $three{\pm}1-stage$ grouping.

  • PDF

Post-outburst observation of HBC722 in Pelican nebula

  • Yang, Yuna;Park, Won-Kee;Sung, Hyunil;Lee, Sanggak;Yoon, Tae-Seog;Lee, Jeongeun;Kang, Wonseok;Park, Keunhong;Cho, Dong-Hwan
    • The Bulletin of The Korean Astronomical Society
    • /
    • v.38 no.1
    • /
    • pp.59.1-59.1
    • /
    • 2013
  • HBC722 (also known as LkHa 188-G4 and PTF 10qpf; A. Miller et al., 2011) is one of the FU Orionis-like young stellar objects which outbursted in August 2010 (Semkov et al., 2010). We have been monitoring the post-outburst phase of this object since November 2010 with Korean Astronomy and Space Science Institute Near Infrared Camera System (KASINICS), at Bohyunsan Optical Astronomy Observatory (BOAO). Four filters, J, H, Ks, and H2 band, were used for this observation. We did aperture photometry to find photometric variation. The light curve shows a long period brightness change. After decrease of the brightness, which was reported at the KAS 2011 fall meeting, HBC722 brightens up slowly now. However we cannot confirm any short period variations, previously reported by Green et al (2013), due to large scatters in the obtained light curve.

  • PDF

High-resolution imaging of microneedles in biological tissue with optical coherence tomography (광간섭 단층 영상기술을 이용한 생체 내 microneedle 삽입 구조 영상)

  • Kim, Hun;Heo, Jung;Lee, Kang Ju;Ryu, Su Ho;Ryu, Won Hyoung;Joo, Chulmin
    • Transactions of the Society of Information Storage Systems
    • /
    • v.9 no.1
    • /
    • pp.17-21
    • /
    • 2013
  • Optical coherence tomography (OCT) allows non-invasive, cross-sectional optical imaging of biological tissue with high spatial resolution and acquisition speed. In principle, it is analogous to ultrasound imaging, but uses near-infrared light instead of ultrasound, measuring the time-delay of back-scattered light from within biological tissue. Compared to ultrasound imaging, it exhibits superior spatial resolution (1~10 um) and high sensitivity. Therefore, OCT has been applied to a wide range of applications such as cellular imaging, ophthalmology and cardiology. Here, we describe a novel application of OCT technology in visualizing microneedles embedded in tissue that is developed to deliver drugs into the dermis without the injection mark in the human skin. Detailed three-dimensional structural images of microneedles and biological tissues were obtained. Examining structural modification of microneedles and tissues during insertion process would enable to evaluate performance of various types of microneedles in situ.

Simulation of photon propagation for transcutaneous optical communication (피부투과 광통신을 위한 세포내 광진행 시뮬레이션)

  • Lee, J.J.;Kim, W.E.;Lee, J.H.;Choi, J.H.;Ahn, J.M.;Choi, W.W.;Park, S.K.;Choi, J.S.;Kim, H.C.;Min, B.G.
    • Proceedings of the KOSOMBE Conference
    • /
    • v.1996 no.11
    • /
    • pp.65-67
    • /
    • 1996
  • Optical property of tissue is characterized by its high scattering of light. In near infrared range$(800{\sim}1200nm)$ scattering is dominant than absorption. Communication using NIR through tissue is applicable to immplantable device. In this paper, simulation of unit impulse response of light in tissue is carried out to estimate the amplitude, phaselength and phaselength deviation.

  • PDF

Resonant inelastic X-ray scattering of tantalum double perovskite structures

  • Oh, Ju Hyun;Kim, Jung Ho;Jeong, Jung Hyun;Chang, Seo Hyoung
    • Current Applied Physics
    • /
    • v.18 no.11
    • /
    • pp.1225-1229
    • /
    • 2018
  • In this paper, we investigated the electronic structures and defect states of $SrLaMgTaO_6$ (SLMTO) double perovskite structures by using resonant inelastic x-ray scattering. Recently, $Eu^{3+}$ doped SLMTO red phosphors have been vigorously investigated due to their higher red emission efficiency compared to commercial white light emitting diodes (W-LED). However, a comprehensive understanding on the electronic structures and defect states of host SLMTO compounds, which are specifically related to the W-LED and photoluminescence (PL), is far from complete. Here, we found that the PL spectra of SLMTO powder compounds sintered at a higher temperature, $1400^{\circ}C$, were weaker in the blue emission regions (at around 400 nm) and became enhanced in near infrared (NIR) regions compared to those sintered at $1200^{\circ}C$. To elucidate the difference of the PL spectra, we performed resonant inelastic x-ray spectroscopy (RIXS) at Ta L-edge. Our RIXS result implies that the microscopic origin of different PL spectra is not relevant to the Ta-related defects and oxygen vacancies.

Optical Imaging Technology for Real-time Tumor Monitoring

  • Shin, Yoo-kyoung;Eom, Joo Beom
    • Medical Lasers
    • /
    • v.10 no.3
    • /
    • pp.123-131
    • /
    • 2021
  • Optical imaging modalities with properties of real-time, non-invasive, in vivo, and high resolution for image-guided surgery have been widely studied. In this review, we introduce two optical imaging systems, that could be the core of image-guided surgery and introduce the system configuration, implementation, and operation methods. First, we introduce the optical coherence tomography (OCT) system implemented by our research group. This system is implemented based on a swept-source, and the system has an axial resolution of 11 ㎛ and a lateral resolution of 22 ㎛. Second, we introduce a fluorescence imaging system. The fluorescence imaging system was implemented based on the absorption and fluorescence wavelength of indocyanine green (ICG), with a light-emitting diode (LED) light source. To confirm the performance of the two imaging systems, human malignant melanoma cells were injected into BALB/c nude mice to create a xenograft model and using this, OCT images of cancer and pathological slide images were compared. In addition, in a mouse model, an intravenous injection of indocyanine green was used with a fluorescence imaging system to detect real-time images moving along blood vessels and to detect sentinel lymph nodes, which could be very important for cancer staging. Finally, polarization-sensitive OCT to find the boundaries of cancer in real-time and real-time image-guided surgery using a developed contrast agent and fluorescence imaging system were introduced.