• 한국광학회지
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• 제12권1호
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• pp.25-31
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• 2001

1차원 이동 변위를 격자의 피치 p보다 1/10 이하의 작은 정밀도로 측정이 가능한 elongated circular gratign(EC 격자)를 가간섭 광원으로 조명하여 Talbot 거리에서 일어나는 Talbot 효과를 실험적으로 확인하였다. 그리고 서로 다른 주기를 갖는 렌즈없이 결상된 EC 격자의 Talbot 상과 고정된 EC 격자의 상호 변위시 이들의 중첩에 의한 Talbot 무아레 무늬를 만들었으며 이를 이용한 한 예로 경사진 평행판의 경사각 정도를 측정하였다. 그리고 한 EC 격자의 Talbot 상과 그 자체의 EC 격자와의 무아레 현상을 이용하여 거울정렬시 미세한 회전각을 가시적으로 매우 쉽게 측정하는 방법을 제안하고 실험하였다.

• 한국광학회지
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• 제5권4호
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• pp.473-480
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• 1994

CARS 신호의 비선형 간섭을 이용하여 여러가지 기체의 비공명 3차 감수율을 측정하였다. 알곤 기체를 기중으로 하기 위하여 기준셀에 알곤 기체를 채우고 시료셀에 측정대상 기체를 주입하여 직렬로 배열하였다. 두 기체 셀 사이에 설치된 위상편이장치의 두께를 바꾸어 가면서 두 기체 셀에서 발생한 CARS 신호의 간섭무늬를 측정하였다. 기체의 전체 비공명 감수율의 값은 여러가지 기체에서 구한 간섭무늬의 진폭으로 부터 구하였다. 각 기체에서 전자만의 기여에 의한 비공명 감수율의 크기를 구하기 위하여 기체의 먼 공명 분광선에 의한 기여를 뺐다. 측정된 결과를 다른 연구자들이 구한 결과와 비교하였다. 본 연구에서 측정된 값의 불확정도는 5% 이내이다.

• 한국세라믹학회지
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• 제42권2호
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• pp.127-131
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• 2005

열처리가 단분산 구형 $SiO_2$ 나노 분말의 자기조립을 통하여 형성된 광자결정 박막의 광특성에 미치는 영향에 대하여 조사하였다. 광밴드갭에 의해 나타나는 반사율 피크는 열처리 온도가 증가함에 따라 단파장 쪽으로 이동하였고, 빛의 회절에 의해 나타나는 Fabry-Perot fringes 피크의 강도도 증가하였다. 또한, 반사율의 절대값도 $250\~300^{\circ}C$ 사이에서 열처리한 시편에서 가장 높은 값을 나타내었다. 미세구조 분석에 따르면 저온열처리를 통하여 입자크기와 결함량이 줄어들고 결정의 치밀도는 증가하였다.

• 대한치과교정학회지
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• 제16권2호
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• pp.43-51
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• 1986

The highly accurate laser holographic interferemotry method was used to determine in what way low-magnitude forces during maxillary expansion are transmitted to the entire maxillary complex and its surrounding structures. The experiments were carried out on a dryed human skull which had a perfectly preserved, normally aligned maxillary dental arch and intact alveolar process. The skull was fixed within a constructed metal frame which ensured maximal stability of the object. The optical equipment and the object were mounted on antivibration table. Interferograms were taken on the lateral and frontal sides of the maxillary complex, using the 10mW He-Ne laser and the double-exposure method. Analysis of the fringe pattern on the recorded object surface was performed by graphically determining the deformation curves related to the bony surface in selected horizontal and vertical planes. On the basis of this study, the following conclusions can be drawn: 1. The density of the interference fringes was gradually increased with the degree of expansion force. 2. Mechanical reactions on the maxillary complex, circummaxillary sutures, and surrounding bones were clearly visible, even with the lowest loading degree. 3. The amount of bone displacement was greater in application of the force after $90^{\circ}$ turn than in initial application of the same force. 4. The direction of interference fringes on the bony surface was similar at all loading degrees.

• Journal of the Optical Society of Korea
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• 제4권1호
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• pp.7-10
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• 2000

The soft x-ray(10nm-100nm) interferometer is a modified Mach-Zehnder type interferometer and it consists of two beam-splitters and four totally reflecting mirrors. The beam-splitters used here are 50% transmission and 50% reflection grating type. The diffraction patterns of beam splitters(1st B.S.) were investigated with a He-Ne laser. The diffraction patterns produced by the soft x-ray interferometer (2nd B.S.) were also investigated in intensities positions. The diffraction patterns of 20 degree grazing incidence on the beam splitters(1st B.S.) show a circular array of spots. Both the reflected and the transmitted beams show the same patterns but symmetric circles on the screen. The maximum intensity appears roughly when n is in the zeroth and odd orders and the suppressed peak(missing order) appears when n is in even orders. Intensities of 3 center fringes(n = 0, $\pm$1) are stronger than others. These results confirm the reduced grating equation and make agree with the intensity distribution function. It was found that the final patterns produced by the soft x-ray interferometer (2nd B.S.) consisted of fine fringes which were caused by two of three diffraction beams that were arrived at the second beam-splitter.

• Current Optics and Photonics
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• 제1권4호
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• pp.295-307
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• 2017

An innovative system for the alternative continuous wide spectral spatial heterodyne spectrometer (ACWS-SHS) is proposed. The relationship between the ACWS-SHS and the wide spectral spatial heterodyne spectrometer (WS-SHS) at the resolution limit, the spectral range, the grating diffraction efficiency and the interference fringes contrast ratio has been analyzed theoretically. Through the comparison of the theoretical analysis and simulation results, it is found that the two systems for the WS-SHS and the ACWS-SHS have the same resolution limit and spectral range, which are ${\delta}{\sigma}$ and ${\sigma}_{01}$, while in the ACWS-SHS system the critical diffraction efficiency of echelle grating is 68.39% and the critical contrast ratio of interference fringes is 0.4135, which is much better than the performance of the WS-SHS system. Therefore, the ACWS-SHS reduces the high requirements for the precision of equipment and expands the application field of SHS effectively.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.930-933
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• 2005

Non-destructive inspection techniques using laser have been breading their application areas as well as growing their measurement skills together with the rapid development of circumferential technology like fiber optics. computer and image processing The ESPI technique is already on the stage of on-line testing with commercial products in developed country nations. Especially, this technique is expected to be applied to the nuclear industry, automobile and aerospace because it is proper for the vibration measurement and it can be applied to objects of a high temperature. This paper describes the use of the ESPI system for measuring vibration patterns on the reflecting objects. Using this system, high-quality Jo fringes for identifying mode shapes are displayed. A bias vibration is introduced into the reference beam to shift the Jo fringes so that fringe shift algorithms can be used to determine vibration amplitude. Using this method. amplitude fields for vibrating objects were obtained directly from the time-average interferometer recorded by the ESPI system.

• 대한기계학회논문집B
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• 제20권3호
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• pp.1040-1049
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• 1996

The high loading combustion is accomplished by making the turbulent intensity strong and the scale small in the premixed combustor. The Da-mkoler number, which is decreased by short turbulent characteristic time or by long chemical reaction time, can make the distributed reaction flame. So we developed a doubled jet burner for high loading combustion. The doubled jet burner was designed to make the scale of the flame small by the effect of impingement and increasing shear stress with doubled jet. We investigated the turbulence characteristics of unburned mixture and visualized several flames with the typical schlieren photography. Then we studied the influence of several factors that related the scale of flame. Consequently, the doubled jet burner can make the eddy very small. And we can obtain the detail information of the flame scale through ADSF(the Average Distance between Successive Fringes) in the micro- schlieren photography. The ADSF is not a exact flame scale, but it has qualitative trend with increasing turbulent intensity. The ADSF is diminished remarkably with increasing turbulent intensity. The reason is that strong turbulent intensity makes the flame zone thick and flamelets numerous. We can confirm this fact by the signal analysis of ion currents.

• 비파괴검사학회지
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• 제10권1호
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• pp.47-55
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• 1990

This paper presents experimental results which explore the capability of a CW laser speckle photography for tile measurement of in-plane displacement at high temperature. The serious restrictions on the application of the method seem to be the ambient air turbulence and the change of surface texture caused by the oxidation, as they tend to decorrelate the double exposured speckle patterns. In order to assess only the effect of air turbulence, a ceramics-coated stainless steel plate is heated in air and Ar-laser specklegrams are made with combination of temperature and lateral translation displacement. The slight reduction in visibility of Young's fringes is observed at $1000^{\circ}C$. The analyses of Young's fringes are carried out by a image processing system using a TV-camera and computers, and the result agrees well with the micrometer reading. Futhermore, uncoated stainless steel and Hastelloy X plates are tested and the effect of oxidation is also evaluated. The experimental results demonstrate that a CW laser speckle photography is applicable at temperatures up to $1000^{\circ}C$.

• 한국광학회지
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• 제9권1호
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• pp.9-14
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• 1998

그림자식 무아레 무늬의 절대차수를 결정할 수 있는 새로운 방법으로 카메라와 광원의 위치좌표는 변화시키지 않고 사방격자의 피치 간격을 일정한 비율로 변화시키는 방법과, 사방격자의 피치간격은 변화시키지 않고 광원과 카메라 사이의 평면위치좌표를 변화시켜서 주기적인 무아레 무늬를 얻었다. 그 결과 사방격자에 의한 큰 주기의 무아레 무늬와 직선격자에 의한 작은 주기의 무아레 무늬를 비교함으로써 직선격자에 의한 무아레 무늬의 절대차수를 결정할 수 있음을 확인하였다.