• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1021-1021
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• 2001

Sample presentation, which means how to set samples to an NIR instrument, is very important in Near Infrared (NIR) Spectroscopy. When sample presentation is not suitable for the samples that you use, very good spectra can not be obtained even if you use a sophisticated NIR instrument. In my presentation, various NIR sample presentations for agricultural products such as intact fruits, single grains, vegetable juice and the others will be explained. In case of peaches with thin peel, the fiber optics of Interactance can be used. However, the fiber optics are not suitable for oranges with relatively thick peel. In this case, transmittance method is useful. As for a small sample such as single grains, a specially designed cell is needed. The cell in transmittance mode has been developed and then applied to single kernels of rice and soybean. In this case we also used the fiber optics. As regards liquid type of sample, a cuvette cell made of quartz in transmittance mode is popular. However, it is time-consuming to wash and dry it. In order to compensate this disadvantage the sample presentation using normal test tubes as sample cells have been developed and applied to milk, rumen juice and urine of a milking cow. An individual test tube can be used for each sample if you use the calibration equation with sample cell compensation. The test tube cell has also been applied to spinach juice for determination of undesirable constituents. It is concluded that sample presentation is most important for NIR Spectroscopy.

• Journal of Sensor Science and Technology
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• v.27 no.4
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• pp.249-253
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• 2018

Infrared transparent ZnS ceramics were synthesized through hydrothermal synthesis ($180^{\circ}C$, 70 h) and sintered using a hot press process at $750^{\circ}C-1000^{\circ}C$. We carried out x-ray diffraction, scanning electron microscopy, and Fourier transform-infrared spectroscopy to confirm the optical properties of the ZnS ceramics after sintering at various temperatures. The phase of ZnS nanopowders was a single phase (cubic) without the hexagonal phase. However, as sintering temperature increased, the formation and increment of hexagonal structures was confirmed. The ZnS ceramic sintered at a temperature of $750^{\circ}C$ showed poor transmittance because it was not completely sintered and because of the pore effect. The ZnS ceramic with the highest transmittance (approximately 69%) was sintered at $800^{\circ}C$. As sintering temperature increased, transmittance gradually decreased owing to the increase in the formation of the hexagonal phase.

• Journal of Sensor Science and Technology
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• v.30 no.6
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• pp.446-450
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• 2021

Non-dispersive infrared (NDIR) gas sensors typically use an optical filter that transmits a discriminating 4.26 ㎛ wavelength band to measure carbon dioxide (CO2), as CO2 absorbs 4.26 ㎛ infrared. The filter performance depends on the transmittance and full width at half maximum (FWHM). This paper presents the fabrication, sensitivity, and selectivity characteristics of a distributed Bragg reflector (DBR)-based Fabry-Perot filter with a simple structure for CO2 detection. Each Ge and SiO2 films were prepared using the RF magnetron sputtering technique. The transmittance characteristics were measured using Fourier-transform infrared spectroscopy (FT-IR). The fabricated filter had a peak transmittance of 59.1% at 4.26 ㎛ and a FWHM of 158 nm. In addition, sensitivity and selectivity experiments were conducted by mounting the sapphire substrate and the fabricated filter on an NDIR CO2 sensor measurement system. When measuring the sensitivity, the concentration of CO2 was observed in the range of 0-10000 ppm, and the selectivity was measured for environmental gases of 1000 ppm. The fabricated filter showed lower sensitivity to CO2 but showed higher selectivity with other gases.

• YAKHAK HOEJI
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• v.42 no.6
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• pp.545-551
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• 1998

Near Infrared transmittance Spectroscopy (NIRS) was used to evaluate and quantify the pharmaceutical active compounds. In the paper, taurine (2-Aminoethanesulfonic acid) was quantitatively analyzed in commercial pharmaceutical preparations. For calibration a central composite factorial design was used to determine concentrations of ingredients in reference samples. For the quantitative analysis of taurine, the most suitable data analysis method includes the calculation of second derivatives and a partial least squares regression (PLSR) model. By NIR spectrometry, combined with PLSR, the taurine concentration was successfully predicted with a relative standard error of prediction (SEP) lower than 1.04%.

• Journal of the Korean Ceramic Society
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• v.32 no.6
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• pp.697-702
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• 1995

The rough growth surfaces of diamond films fabricated by the hot filament CVD were polished using thermomechanical polishing method. And then, its application to the optical windows was discussed through the measurement of transmittance in the range of infrared radiation and analysis of surfaces structure. The results were compaerd with those of the films polished with conventional mechanicla polishing. The transmittance of the mechanically polished film reached 57~66% over the whole range from 500 to 4000 cm-1. But the transmittance of the film polished with thermomechanical polishing method was reduced below 35%. This decrease in transmittance was due to both the graphitization of diamond on the polished surface and the growth of $\beta$-SiC at diamond/Si interface during polishing. The residual Fe in hte thermomechanically polished surface was confirmed by SIMS analysis. This Fe played the role of the graphitization of near surface region of the diamond film.

• Journal of Sensor Science and Technology
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• v.24 no.4
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• pp.264-269
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• 2015

An infrared (IR) bolometer measures the change of resistance by absorbing incident IR radiation and generates a signal as a function of the radiation intensity. Since a bolometer requires temperature stabilization and light filtering except for the infrared rays, it is essential for the device to be packaged meeting conditions that above mentioned. Minimization of heat loss is needed in order to stabilize temperature of bolometer. Heat loss by conduction or convection requires a medium, so the heat loss will be minimized if the medium is a vacuum. Therefore, vacuum packaging for bolometer is necessary. Another important element in bolometer packaging is germanium (Ge) window, which transmits IR radiation to heat the bolometer. To ensure a complete transmittance of IR light, anti-reflection (AR) coatings are deposited on both sides of the window. Although the transmittance of Ge window is high for IR rays, it is difficult to use frequently in low-price IR bolometer because of its high price. In this paper, we fabricated IR window by utilizing silicon (Si) substrate instead of Ge in order to reduce the cost of bolometer packaging. To enhance the IR transmittance through Si substrate, it is textured using Reactive Ion Etching (RIE). The texturing process of Si substrate is performed along with the change of experimental conditions such as gas ratio, pressure, etching time and RF power.

• Journal of Sensor Science and Technology
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• v.30 no.4
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• pp.250-254
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• 2021

A highly sensitive and selective non-dispersive infrared (NDIR) carbon dioxide gas sensor requires achieving high transmittance and narrow full width at half maximum (FWHM), which depends on the interface of the optical filter for precise measurement of carbon dioxide concentration. This paper presents the design, simulation, and fabrication of a Fabry-Perot filter based on a distributed Bragg reflector (DBR) for a low-cost NDIR carbon dioxide sensor. The Fabry-Perot filter consists of upper and lower DBR pairs, which comprise multilayered stacks of alternating high- and low-index thin films, and a cavity layer for the resonance of incident light. As the number of DBR pairs inside the reflector increases, the FWHM of the transmitted light becomes narrower, but the transmittance of light decreases substantially. Therefore, it is essential to analyze the relationship between the FWHM and transmittance according to the number of DBR pairs. The DBR is made of silicon and silicon dioxide by RF magnetron sputtering on a glass wafer. After the optimal conditions based on simulation results were realized, the DBR exhibited a light transmittance of 38.5% at 4.26 ㎛ and an FWHM of 158 nm. The improved results substantiate the advantages of the low-cost and minimized process compared to expensive commercial filters.

• Journal of the Society of Naval Architects of Korea
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• v.48 no.4
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• pp.336-341
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• 2011

Ship infrared signature is the cause of detection and tracking by infrared sensor and anti-ship missile seeker. Recent warships have been applied the infrared stealth technology to reduce own ship infrared signature and tested to validate own ship infrared signature level. This study describes the two issues. Firstly, we describe the infrared measurement concept and infrared signature level establishment method that have been performed. Secondly, we compare and analyze the error components between the infrared measurement and simulation result.

• Journal of Sensor Science and Technology
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• v.28 no.4
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• pp.256-261
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• 2019

In this study, mid-infrared transparent zinc sulfide (ZnS) ceramics were fabricated through hydrothermal synthesis with different molar ratios of S/Zn (S/Zn = 0.8, 1.0, 1.2, 1.4, and 1.6). The ZnS ceramics were sintered at a relatively low temperature of $850^{\circ}C$ to prevent the occurrence of the hexagonal phase featuring optical anisotropy. The phase composition, microstructure, and optical properties of the ZnS ceramics were subsequently investigated by employing X-ray diffraction, scanning electron microscopy, and Fouriertransform infrared spectroscopy. The results obtained indicate that the ZnS nanoparticles feature the cubic phase, without the hexagonal phase. Moreover, with increasing S, the crystallinity and particle size of the ZnS nanoparticles increased. The crystallinity and density of the ZnS ceramics improved when the molar ratio of S was higher than the molar ratio of Zn, thereby enhancing the transmittance. Furthermore, the ZnS ceramic with an S/Zn value of 1.2 was found to exhibit the highest transmittance of approximately 69% owing to the reduced occurrence of the hexagonal phase and a high density of 99.8%.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.3111-3111
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• 2001

The implementation of NIR and chemometrics in the Pharmaceutical industries is still in strong progress, both regarding qualitative and quantitative applications and beneficial results are seen. Looking at the development so far, NIR will change the pharmaceutical industry even more in the future. This presentation will address the experiences and progress achieved regarding the application and implementation of quantitative methods for determination of content uniformity and assay of tablets with less than 10% w/w of active, using Near Infrared transmittance spectroscopy in combination with PLS. Also qualitative methods for identification of the same tablets by Near Infrared reflectance spectroscopy will be discussed. Four commercial tablet strengths are formulated and produced from two different compositions by direct compression. Three different strengths are dose proportional, i.e. fixed concentration by varying in size. The aim was to replace the conventional primary methods for analysing content uniformity, assay and identification by NIR. Studies were performed on comparing transmittance versus reflectance spectroscopy for both applications on the dose proportional tablets. The model for determination of content uniformity and assay was developed to cover both coated and uncoated tablets, whereas the qualitative model was developed to identify coated tablets only. The impact of the tablet formulation, tablet size and coating, resulted in individual models far each composition The best calibration was achieved using diffuse reflectance for the identification purposes and diffuse transmittance for the quantitative determination of the active content within the tablets. As NIR in combination with other techniques opens up the possibility of total quality management within the production, the transfer of the above-mentioned models from a laboratory based approach to an at-line approach at H.Lundbeck will be addressed too.