• 대한기계학회논문집A
• /
• 제27권1호
• /
• pp.102-108
• /
• 2003

Recently, the authors have developed a new material test system fur thin film at the high temperature. It is so compact and precise with sub micron resolution that it seems to be a useful tool fur research of the oxide film growth, its mechanical behavior and failure mechanism. To this end. in this paper three methologies are described for in-situ monitoring of the displacement & strain and the temperature, the oxide thickness. These are the Laser Speckle analysis with digital image correlation technique, the two-color infra-red thermometer and the laser reflection interferometry respectively. The calibration results and some issues which should be addressed for practical application are presented.

• 유체기계공업학회:학술대회논문집
• /
• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
• /
• pp.517-518
• /
• 2006

Transient and asymmetric density distributions have been investigated by three-dimensional digital speckle tomography with a novel integration method. Multiple CCD images captured movements of speckles in three angles of view simultaneously because the flows were asymmetric and unsteady. The speckle movements which have been formed by a ground glass between no flow and downward butane flow from a circular half opening have been calculated by a cross-correlation tracking method so that those distances can be transferred to deflection angles of laser rays for density gradients. A novel integration method has been developed to obtain projection data from the deflection angles for the speckle tomography.'The three-dimensional density fields have been reconstructed from the accurate projection values by a real-time multiplicative algebraic reconstruction technique (MART) with the developed integration method.

• 마이크로전자및패키징학회지
• /
• 제17권2호
• /
• pp.29-33
• /
• 2010

Among several critical topics in semiconductor fabrication technology, particles in addition to bonded surface contaminations are issues of great concerns. This study reports the development of a system which inspects wafer bond integrity by analyzing laser beam transmittance deviations and the variations of the intensity caused by the defect thickness. Since the speckling phenomenon exists inherently as long as the laser is used as an optical source and it degrades the inspection accuracy, speckle contrast is another obstacle to be conquered in this system. Consequently speckle contrast reduction methods were reviewed and among the all remedies have been established in the past 30 years the most adaptable solution for inline inspection system is applied. Simulation and subsequently design of experiments has been utilized to discover the best solution to improve irradiance distribution and detection accuracy. Comparison between simulation and experimental results has been done and it confirms an outstanding detection accuracy achievement. Bonded wafer inspection system has been developed and it is ready to be implemented in FAB in the near future.

• 한국정밀공학회지
• /
• 제25권3호
• /
• pp.101-108
• /
• 2008

Residual stress is one of the causes which make defects in engineering components and materials. Many methods have been developing to measure the residual stress. Though these methods provide the information of the residual stress, they also have disadvantage like a little damage, time consumption, etc. In this paper, we devised a new experimental technique to measure residual stress in materials with a combination of laser speckle pattern interferometry and spot heating. The speckle pattern interferometer measures in-plane deformation during the heat provides for much localized stress relief. 3-D shape is used for determining heat temperature and other parameters. The residual stresses are determined by the amount of strain that is measured subsequent to the heat and cool-down of the region being interrogated. A simple model is presented to provide a description of the method. In this paper, we could experimentally confirm that residual stress can be measured by using laser interferometry and spot heating method.

• 한국정밀공학회지
• /
• 제9권4호
• /
• pp.90-99
• /
• 1992

In resent year Laser Speckle and its development have enabled surface deformation of engineering components and materials to be interferometrically examined. Laser Speckle- Pettern Interferometry Method is a very useful method for measuring In-plane components of displacement. In measuring thermal expansion coefficient, the various problems generated were established, and the measuring limitation examined. Metarial INCONEL 601 was used in experiments. Specimen was heated to the high temperature(100$0^{\circ}C$) by diong current to the direct two specimen. Then, those problems appear to the influence of back-ground radiation by the heated specimen, the influence by air turbulence, the oxidation of specimen. The color monitor and interference filter prevented the back-ground radiation by rad heat. The oxidation occuring in specimen itself was not generated by the being acid-proof excellence of material INCONEL 601. Yet, in this experiments, the serious problems are the oxidation of specimen and influence by air turbulence. By more reserching these problems forward, it is helpful that the thermal expansion coefficient of many materials is directly measured under high temperature.

• Journal of the Optical Society of Korea
• /
• 제17권1호
• /
• pp.86-90
• /
• 2013

Various methods have been proposed for enhancing the contrast of laser speckle contrast image (LSCI) in subcutaneous blood flow measurements. However, the LSCI still suffers from low image contrast due to tissue turbidity. Herein, a physicochemical tissue optical clearing (PCTOC) method was employed to enhance the contrast of LSCI. Ex vivo and in vivo experiments were performed with porcine skin samples and male ICR mice, respectively. The ex vivo LSCIs were obtained before and 90 min after the application of the PCTOC and in vivo LSCIs were obtained for 60 min after the application of the PCTOC. In order to obtain the skin recovery images, saline was applied for 30 min after the application of the PCTOC was completed. The visible appearance of the tubing under ex vivo samples and the in vivo vasculature gradually enhanced over time. The LSCI increased as a function of time after the application of the PCTOC in both ex vivo and in vivo experiments, and properly recovered to initial conditions after the application of saline in the in vivo experiment. The LSCI combined with the PCTOC was greatly enhanced even in deep vasculature. It is expected that similar results will be obtained in in vivo human studies.

• 한국광학회지
• /
• 제31권6호
• /
• pp.268-273
• /
• 2020

레이저 빔이 산란 매질에서 반사될 때 발생하는 스펙클 패턴을 모니터링함으로써 산란 매질에 입사하는 레이저 빔들의 결맞는(coherent) 결합 상태를 분석하고자 하였다. 이를 위하여 가간섭성이 높은 3개의 시준 레이저 광원을 자유공간에서 렌즈를 이용하여 무작위 표면특성을 가진 산란목표물(scattering target)에 집속한 후, 되돌아오는 빔의 스펙클 패턴을 푸리에 영역에서 살펴보았다. 목표물에 입사하는 단일 레이저 빔의 크기변화 및 3개 결맞는 레이저 빔 간의 공간적인 빔결합 정도에 따라 스펙클 패턴의 평균적인 크기가 변하게 되는데, 이를 푸리에 영역에서 분석함으로써 결맞음 빔결합의 효율을 판별할 수 있는 단일 모니터링 변수를 도출할 수 있었다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2008년도 추계학술대회 논문집
• /
• pp.743-744
• /
• 2008

• Current Optics and Photonics
• /
• 제3권6호
• /
• pp.555-565
• /
• 2019

Development of a biomarker for predicting tumor-treatment efficacy is a matter of great concern, to reduce time, medical expense, and effort in oncology therapy. In a preclinical study, we hypothesized that the blood-flow parameter based on laser speckle flowmetry (LSF) could be a potential indicator to estimate the efficacy of breast-cancer treatment. To verify this hypothesis, a 13762-MAT-B-III rat breast tumor was grown in a dorsal skinfold window chamber applied to a nude mouse, and the change in blood flow rate (BFR) - or the speckle flow index (SFI) is used together as the same meaning in this manuscript - was longitudinally monitored during tumor growth and metronomic cyclophosphamide treatment. Based on the daily LSF angiogram, several BFR parameters (baseline SFI, normalized SFI, and △rBFR) were compared to tumor size in the normal, treated, and untreated tumor groups. Despite the incomplete tumor treatment, we found that the daily changes in all BFR parameters tended to have partially positive correlation with tumor size. Moreover, we observed that the changes in baseline SFI and normalized SFI responded one day earlier than the tumor shrinkage during chemotherapy. However, daily variations in the hypercapnia-induced △rBFR lagged tumor shrinkage by one day. This study would contribute not only to evaluating tumor vascular response to treatment, but also to monitoring blood-flow-mediated diseases (in brain, skin, and retina) by using LSF in preclinical settings.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2000년도 하계종합학술대회 논문집(2)
• /
• pp.119-122
• /
• 2000

스페클 패턴은 광섬유의 모드 간섭 때문에 발생하는 현상으로, 광섬유에 인가된 미세 외압으로 인해서 발생하는 스페클 패턴의 변화를 이용해 외부압력의 인가여부 및 그 크기를 알 수 있다. 이를 이용하여 본 연구에서는 미세 압력을 외부에서 인가하며 스페클 패턴의 변화에 따른 광 강도의 변화를 측정하였으며, 그 신호는 증폭기와 필터를 거쳐 오실로스코프로 관찰하였다. 그 결과 우리는 이 신호를 관찰하여 부하인가에 대한 응답특성을 실시간에 정확히 확인할 수 있었다. 본 연구에서 제작된 센서는 기존의 센서에 비해 매우 높은 감도를 가지고 넓은 영역을 실시간에 감시할 수 있으며, 저 비용으로 센서를 설계·제작이 가능하므로 범용의 방재용 센서 및 침입 센서에 응용 가능할 것으로 기대된다.