• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.557-564
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• 2017

The purpose of the thermal imaging observation device mounted on the K's tank in the Republic of Korea military is to convert infrared rays into visual information to provide information about the environment under conditions of restricted visibility. Among the various performance indicators of thermal observation devices, such as the view, magnification, resolution, MTF, NETD, and Minimum Resolvable Temperature Difference (MRTD), the MRTD is the most important, because it can indicate both the spatial frequency and temperature resolvable. However, the standard method of measuring the MRTD in NATO contains many subjective factors. As the measurement result can vary depending on subjective factors such as the human eye, metal condition and measurement conditions, the MRTD obtained is not stable. In this study, these qualitative MRTD measurement systems are converted into quantitative indicators based on a gray scale using imaging processing. By converting the average of the gray scale differences of the black and white images into the MRTD, the mean values can be used to determine whether the performance requirements required by the defense specification are met. The (mean) value can also be used to discriminate between detection, recognition and identification and the detectable distance of the thermal equipment can be analyzed under various environmental conditions, such as altostratus, heavy rain and fog.

• The Optical Journal
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• s.122
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• pp.41-43
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• 2009

본 연구에서는 최근에 민수용으로 활용 빈도가 높은 $320{\times}240$ 어레이를 갖는 비냉각 검출기에 적합하도록 F/1.0. 이중배율 광학계를 설계제작하여 열영상을 획득하고 광학성능을 확인하기 위하여 최소분해가능온도차(MRTD; Minimum Resolvable Temperature Difference) 값을 측정하고 사람과 차량의 탐지를 추정하였다.

• Korean Journal of Optics and Photonics
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• v.16 no.4
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• pp.354-360
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• 2005

A high performance LWIR(long wavelength infra red) zoom thermal imaging sensor using $480{\times}6$ HgCdTe(MCT) linear detector has been developed by ADD Korea. The optical system consists of zoom telescope having large objective about 190 mm diameter and optically well corrected scanning system. The zoom ratio of the telescope is 3: 1 and its magnification change is performed by moving two lens groups. And also these moving groups are used for athermalization of the system. It is certain that the zoom sensor can be used in wide operating temperature range without any degradation of the system performance. Especially, the sensor image can be displayed with the HDTV(high definition television) format of which aspect ratio is 16:9. In case of HDTV format, the scanning system is able to display 620,000 pixels. This function can make wider horizontal field of view without any loss of performance than the normal TV format image. The MRTD(minimum resolvable temperature difference) of the LWIR thermal imaging sensor shows good results below 0.04 K at spatial frequency 2 cycles/mrad and 0.23 K at spatial frequency 8 cycles/mrad at the narrow field of view.

• Korean Journal of Optics and Photonics
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• v.15 no.5
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• pp.423-428
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• 2004

The development of a compact and high performance MWIR thermal imaging sensor based on the SOFRADIR 320${\times}$240 element IRCCD detector is described. The sensor has 20 magnification zoom optics with the maximum 40$^{\circ}$${\times}$30$^{\circ}$ of super wide field of view and 7.6 cycles/mrad of resolving power with the operation of attached micro-scanning system. In order to correct nonuniformities of detector arrays, we have proposed a multi-point correction method using defocusing of the optics and we have acquired the highest quality images. The MRTD of our system shows good results below 0.05K at spatial frequency 1 cycles/mrad at narrow field of view. Experimental data and obtained performances are presented and discussed.

• Korean Journal of Optics and Photonics
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• v.16 no.3
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• pp.209-216
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• 2005

A new second generation advanced thermal imager, which can be used for battle tank sight has been developed by ADD. This system uses a $480\times6$ TDI HgCdTe detector, operating in the $7.7-10.3{\mu}m$ wavelength made by Sofradir. The IR optics has dual field of views such as $2.67\times2^{\circ}$ in NFOV and $10\times7.5^{\circ}$ in WFOV. And also, this optics is used for athermalization of the system. It is certain that our sensor can be used in wide temperature range without any degradation of the system performance. The scanning system to be able to display 470,000 pixels is developed so that the pixel number is greatly increased comparing with the first generation thermal imaging system. In order to correct non-uniformity of detector arrays, the two point correction method has been developed by using the thermo electric cooler. Additionally, to enhance the image of low contrast and improve the detection capability, we have proposed the new technique of histogram processing being suitable for the characteristics of contrast distribution of thermal imagery. Through these image processing techniques, we obtained the highest quality thermal image. The MRTD of the LWIR thermal sight shows good results below 0.05K at spatial frequency 2 cycles/mrad at the narrow field of view.