• Journal of the Optical Society of Korea
• /
• 제17권2호
• /
• pp.213-218
• /
• 2013

Although infrared focal plane array (IRFPA) detectors have been commonly used, non-uniformity correction (NUC) remains an important problem in the infrared imaging realm. Non-uniformity severely degrades image quality and affects radiometric accuracy in infrared imaging applications. Residual non-uniformity (RNU) significantly affects the detection range of infrared surveillance and reconnaissance systems. More effort should be exerted to improve IRFPA uniformity. A novel NUC method that considers the surrounding temperature variation compensation is proposed based on the binary nonlinear non-uniformity theory model. The implementing procedure is described in detail. This approach simultaneously corrects response nonlinearity and compensates for the influence of surrounding temperature shift. Both qualitative evaluation and quantitative test comparison are performed among several correction technologies. The experimental result shows that the residual non-uniformity, which is corrected by the proposed method, is steady at approximately 0.02 percentage points within the target temperature range of 283 K to 373 K. Real-time imaging shows that the proposed method improves image quality better than traditional techniques.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제5권1호
• /
• pp.45-51
• /
• 2005

We have developed surface micromachined Infrared ray (IR) focal plane array (FPA), in which single $SiO_{2}$ layer works as an IR absorbing plate and $Pb(Zr_{0.3}Ti_{0.7})O_{2}$ thin film served as a thermally sensitive material. There are some advantages of applying $SiO_{2}$ layer as an IR absorbing layer. First of all, the $SiO_{2}$ has good IR absorbance within $8{\sim}12{\mu}m$ spectrum range. Measured value showed about 60% absorbance of incident IR spectrum in the range. $SiO_{2}$ layer has another important merit when applied to the top of Pt/PZT/Pt stack because it works also as a supporting membrane. Consequently, the IR absorbing layer forms one body with membrane structure, which simplifies the whole MEMS process and gives robustness Ito the structure.

• 한국항공우주학회지
• /
• 제33권10호
• /
• pp.98-103
• /
• 2005

해상도 2.5m 급 지구관측 카메라인 MAC(Medium-sized Aperture Camera)의 비행모델이 정렬 및 조립되었다. 본 논문에서는 지상에서 측정한 MAC의 시스템 MTF 성능, MTF를 이용한 초점면부의 정렬 등에 대해 논의한다. 칼날주사방식을 이용하여 MAC의 시스템 MTF를 측정하였고, 이를 위해 회절한계 성능의 구경 450 mm 급의 카세그레인 시준기를 만들어 사용하였다. 시스템 MTF를 이용하여 CCD 검출기 초평면부의 최적의 초점에 정렬하였다.

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

• 항공우주시스템공학회지
• /
• 제9권4호
• /
• pp.23-30
• /
• 2015

The focal plane image stabilization for a camera is one of the most effective method that can increases the digital camera's image quality by compensating the vibration disturbance. The optical image stabilization can be implemented by making the focal plane to trace the path of incident light. To control the position of focal plane motion compensating stage precisely, a nonlinear control algorithm has been applied by considering coulomb friction which is nonlinear behavior of the compensator system. In our study, we have analyzed the hand shaking vibration using the gyro sensor, and made a mathematical model of compensating stage containing optical sensor and piezo-actuator. Then the nonlinear control algorithm has been designed and its performance has been verified by experiment. In this study, a friction driven peizo-electric actuator with $1{\mu}m$ resolution and 10mm/s speed has been used for stage movement.

• 전자공학회논문지A
• /
• 제32A권12호
• /
• pp.36-47
• /
• 1995

The main purpose of this paper is to determine a new focal point and field distribution due to the shape deformation of reflector antenna by numerical method such as geometrical optics and the aperture field method. It is shown the 4 types deformations to be added into original shape of parabola antenna and offset antenna: linear, quadratic, cubic and hybrid distortion. These results can be applied to deformed reflector antenna in order to fit a focal point and radiation pattern.

• 한국통신학회논문지
• /
• 제21권10호
• /
• pp.2670-2678
• /
• 1996

Reticle seekers temporally modulate target location onto the incoming spatial signal. When large or multiple targets are present in the FOV, however, it is hard to precisely modulate the incoming target signal by the relicle. To solve this loss of modulatoin depth problem, we present an improved retical seeker using the segmented focal plane array(FPA). The new reticle system uses the normalized difference as well as the modulated signal of each detector output in the segmented FPA. In simulation, we have ascertained the proposed system can make an effective analysis and tracking for multiple or large targets.

• 한국광학회지
• /
• 제3권1호
• /
• pp.16-19
• /
• 1992

회절격자와 굴절률을 알고있는 액체내에 있는 렌즈사이의 퓨리에 변환관계를 이용하여 렌즈 굴절률에 대한 수식을 유도하였다. 층밀리기 간섭기술을 이용하여 정확한 렌즈의 후면촛평면의 위치를 결정하였으며 슬릿을 스텝핑 모터로 구동하는 이동장치에 부착시켜 회절격자의 퓨리에 변환 스펙트럼 간격을 축정하였다. 세가지 액체를 사용하여 얇은 렌즈의 굴절률을 측정하였으며 높은 측정정확도를 확인하였다.

• Current Optics and Photonics
• /
• 제2권2호
• /
• pp.147-152
• /
• 2018

We propose a novel bi-focal metallic Fresnel zone plate (MFZP) with shallow depth-of-field (DOF) characteristics. We design the specific annular slit patterns, exploiting the phase-selection-rule method along with the particle swarm optimization algorithm, which we have recently proposed. We numerically investigate the novel characteristics of the bi-focal MFZP in comparison with those of another bi-focal MFZP having equivalent functionality but designed by the conventional multi-zone method. We verify that whilst both bi-focal MFZPs can produce dual focal spots at $15{\mu}m$ and $25{\mu}m$ away from the MFZP plane, the former exhibits characteristics superior to those of the latter from the viewpoint of axial resolution, including the axial side lobe suppression and axial DOF shallowness. We expect the proposed bi-focal MFZP can readily be fabricated with electron-beam evaporation and focused-ion-beam processes and further be exploited for various applications, such as laser micro-machining, optical trapping, biochemical sensing, confocal sensing, etc.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2003년도 춘계학술대회 논문집
• /
• pp.280-283
• /
• 2003

In this paper, there was finding laser beam focal length using the camera at the work with laser preprocess. A process have some similarity that the laser direct writing was condition of unused other light source in order to a partical object of working substrate, so we worked finding focal length using yellow light. As we found focal lengths from three points of substrate edges, The focal length of all substrates was able to be computed by calculating a plane equation using these three point. Also we make a device and software that can automatically perform all of the processes.