소형 분광계 기반 간섭계를 이용한 투명한 샘플의 두께 측정 방법

이승석,김주하,김은선,최남건,최은서 한국물리학회 2016 새물리 Vol.66 No.9

In this paper, a interferometer composed of a single fiber and a compact spectrometer is proposed, and the results of thickness measurements on a transparent cover glass by using the proposed interferometer are presented. The proposed interferometer has used a broadband source as a light source and the compact spectrometer as a detector, and a common-path interferometer was implemented with a single fiber. The implemented interferometer was used to measure the interference in the spectral domain to prevent mechanical movement in the reference arm. Three pieces of cover glass, equal with a thickness of 130 $\mu$m, were used for preparing samples having different thicknesses. The thicknesses of the samples were measured by using the implemented interferometer. The error in the measurement results was less than 4%, which was very similar to the minimum error level of the proposed system. The proposed interferometer, with improving portability, can be used as an alternative to a conventional bulk optics-based interferometer. Although a limitation in the measurable thickness caused by the restricted number of pixels was given, the compact spectrometer-based interferometer could be applied to transparent samples with thicknesses of a few hundred micrometers. 본 논문에서는 단일 광섬유와 소형 분광계로 구성된 간섭계를 제안하였고 이를 이용하여 투명한 커버 글라스의 두께를 측정한 결과를 제시하였다. 제안한 간섭계의 광원으로는 광대역 광원을 측정기로는 소형 분광계를 이용하였고 단일 광섬유로 공통경로 간섭계를 구성하였다. 구현한 간섭계는 기준단의 기계적 움직임 없이 간섭무늬를 측정하기 위해서 스펙트럼 영역에서 간섭무늬를 측정하였다. 두께가 130 $\mu$m인 커버 글라스 3개를 이용하여 두께가 다른 샘플들을 만들었고 구현한 간섭계를 이용하여 각 샘플들의 두께를 측정하였다. 측정된 샘플들의 두께는 4% 이내의 오차로 제안한 시스템의 최소 오차 수준에 근사하였다. 제안한 간섭계는 이동성을 향상시킬 수 있으면서도 동시에 기존의 벌크 광학계 기반의 간섭계를 충분히 대치할 수 있는 대안이 될 것이다. 제한된 픽셀수로 인해서 측정할 수 있는 두께의 제약을 가지고 있지만 제안한 소형 분광계 기반 간섭계는 수백 $\mu$m의 두께를 가지는 투명한 샘플에 응용이 가능할 것이다.

삼차원 좌표 측정을 위한 부피 간섭계의 오차분석 및 성능평가

이혁교,주지영,김승우 한국광학회 2002 한국광학회지 Vol.13 No.6

본 연구에서는 삼차원 공간상에서 절대 좌표를 측정하기 위한 부피 간섭계의 오차원인을 분석하고 각 오차원인이 최종 결과에 미치는 영향을 계산했다. 계산결과 광검출기 배열의 비선형성, 압전소자의 비선형성, 광섬유 내부의 온도변화 둥이 오차의 주요 원인임을 알 수 있다. 제안된 간섭계의 성능을 실험적으로 검증하기 위해 분해능 측정 및 이차원 광학식 스케일과의 비교를 수행했다. 또한 간섭계의 성능을 좀 더 엄밀하게 검증하기 위해 자가보정법을 적용해서 공간상에서 간섭계가 갖는 계통오차를 추출했으며 60mm$\times$60mm$\times$20mm공간에서 최대오차 1 $\mu\textrm{m}$ 이하를 얻었다. We have recently proposed the new concept of a phase-measuring volumetric interferometer that enables us to accurately measure the xyz-coordinates of the probe without metrology frames. The interferometer is composed of a movable target and a fixed photo-detector array. The target is made of point diffraction sources to emit two spherical wavefronts, whose interference is monitored by an array of photo-detectors. Phase shifting is applied to obtain the precise phase values of the photo-detectors. Then the measured phases are fitted to a geometric model of multilateration so as to determine the xyz-location of the target by minimizing least square errors. The proposed interferometer has been designed and built with a volumetric uncertainty of less than 1.0 $\mu\textrm{m}$ within a cubic working volume of side 120 mm. Here, in this paper, we also present error sources, an evaluated uncertainty, and test results from the prototype system. The self-calibration of two-dimensional precision metrology stages is applied to test the performance of the interferometer.

층밀림 간섭계를 이용한 부피간섭계의 개선

주지영(J. Chu),김승우(S.-W. Kim) 한국정밀공학회 2005 한국정밀공학회 학술발표대회 논문집 Vol.2005 No.10월

The volumetric interferometer, which uses the interference of wavefronts emitted from two single mode fibers, measures the target position in 3-D. In this paper, we suggest a new calculation method which doesn’t need a non-linear optimization and an initial guess. We find the relationship between the coefficients of the Zernike polynomials for a spherical wavefront and its center and reconstruct a spherical wavefront by using the Zernike polynomials from two interference fringes like a lateral shearing interferometer. The target position can be obtained from the coefficients of the Zernike polynomials of the reconstructed wavefront. We can get the target position in 3-D with sub-μm errors in a simulation.

레이저 유도 초음파를 이용한 재료평가 및 비파괴 검사 시스템개발에 관한 연구

김재열,송경석,김창현,김유홍 한국공작기계학회 2004 한국공작기계학회 추계학술대회논문집 Vol.2004 No.-

In the present study, a Nd;YAG Laser (pulse type) was used to emit ultrasonic signals to a test material. In addition, a total ultrasonic investigation system was designed by adopting a Fabry-Perot interferometer, which receives ultrasonic signals without any contact. For non-destructive test SM45C, which contains some flaws was used as a test material. Because it is easy to align light beam in receiver, and the length of the light beam does not change much even if convex mirror leans towards one side, confocal Fabry-Perot interferometer, which has stable frequency, and PI control are used to correct interfered and unstable signals from temperature, fluctuation and time shift of laser frequency. Stable signals are always obtained by the feedback of PI circuit signals in the confocal Fabry-Perot interferometer. The type, size and position of flaws inside the test material were examined by achieving the stabilization of an interferometer. This study presented a useful method, which could quantitatively investigate the fault of objects by using a Fabry-Perot interferometer.

Michelson 간섭계에 의한 고체의 선팽창계수 측정방법

김홍균,김영선 한국공학교육학회 2013 공학교육연구 Vol.16 No.2

This paper deals with the measurement theory and technique of linear expansion coefficient for solid material using Michelson interferometer. The Michelson interferometer produces interference fringes by splitting a beam of monochromatic light so that one beam strikes a fixed mirror and the other a movable mirror. When the reflected beams are brought back together, an interference pattern results. Precise distance measurements until a quarter of wave length can be made with the Michelson interferometer by moving the mirror and counting the interference fringes which move by a photo diode. This paper represents the application of Michelson interferometer for measuring infinitesimal length system and shows the measurement method of linear expansion coefficients for various materials like copper, aluminum and iron. the results are good agreement with theoretical value within margin of error for each materials.

레이저 유도 초음파를 이용한 재료평가 및 비파괴 검사 시스템 개발에 관한 연구

김재열(Jeal-Yel Kim),송경석(Kyung-Seok Song),김창현(Chang-Hyun Kim),김유홍(Yoo-Hong Kim) 한국생산제조학회 2004 한국생산제조시스템학회 학술발표대회 논문집 Vol.2004 No.10

In the present study, a Nd;YAG Laser (pulse type) was used to emit ultrasonic signals to a test material. In addition, a total ultrasonic investigation system was designed by adopting a Fabry-Perot interferometer, which receives ultrasonic signals without any contact. For non-destructive test SM45C, which contains some flaws was used as a test material. Because it is easy to align light beam in receiver, and the length of the light beam does not change much even if convex mirror leans towards one side, confocal Fabry-Perot interferometer, which has stable frequency, and PI control are used to correct interfered and unstable signals from temperature, fluctuation and time shift of laser frequency. Stable signals are always obtained by the feedback of PI circuit signals in the confocal Fabry-Perot interferometer. The type, size and position of flaws inside the test material were examined by achieving the stabilization of an interferometer. This study presented a useful method, which could quantitatively investigate the fault of objects by using a Fabry-Perot interferometer.

서브나노급 정밀도의 2차원 원자현미경 개발

이동연(Dong-Yeon Lee),권대갑(Dae-Gab Gweon) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11

A compact and two-dimensional atomic force microscope (AFM) using an orthogonal sample scanner, a calibrated homodyne laser interferometer and a commercial AFM head was developed for use in the nanometrology field. The x and y position of the sample with respect to the tip are acquired by using the laser interferometer in the open-loop state, when each z data point of the AFM head is taken. The sample scanner which has a motion amplifying mechanism was designed to move a sample up to 100 × 100 ㎛² in orthogonal way, which means less crosstalk between axes. Moreover, the rotational errors between axes are measured to ensure the accuracy of the calibrated AFM within the full scanning range. The conventional homodyne laser interferometer was used to measure the x and y displacements of the sample and compensated via an X-ray interferometer to reduce the nonlinearity of the optical interferometer. The repeatability of the calibrated AFM was measured to sub-nm within a few hundred nm scanning range.

The Small Angle Generator Based on a Laser Angle Interferometer

Tae Bong Eom,Don Young Jeong,Jae Wan Kim 한국정밀공학회 2007 International Journal of Precision Engineering and Vol.8 No.3

To calibrate precision autocollimators, the Korean Research Institute of Standards and Science (KRISS) has built a small angle generator using a laser interferometer. The system is based on a sine bar mechanism in which the angle is determined from the ratio of two lengths. The rotational angle is measured by the angle interferometer and the heterodyne laser interferometer detects the relative displacement of two retro-reflectors attached to the rotating arm. The distance between the two retro-reflectors of the laser angle interferometer is self-calibrated by an index table positioned on the rota ling arm. The resolution of the system is 0.002 seconds. and the accuracy is better than 0.04 seconds within a measuring range of i: I degree. The small angle generator can also be used with an index table that can divide one circle into 1440 angles. The combined system can generate any angle over 360 degrees to an accuracy of 0.11 seconds.

The Small Angle Generator Based on a Laser Angle Interferometer

Eom, Tae-Bong,Jeong, Don-Young,Kim, Jae-Wan Korean Society for Precision Engineering 2007 International Journal of Precision Engineering and Vol.8 No.3

To calibrate precision autocollimators, the Korean Research Institute of Standards and Science (KRISS) has built a small angle generator using a laser interferometer. The system is based on a sine bar mechanism in which the angle is determined from the ratio of two lengths. The rotational angle is measured by the angle interferometer and the heterodyne laser interferometer detects the relative displacement of two retro-reflectors attached to the rotating arm. The distance between the two retro-reflectors of the laser angle interferometer is self-calibrated by an index table positioned on the rotating arm. The resolution of the system is 0.002 seconds, and the accuracy is better than 0.04 seconds within a measuring range of $\pm$1 degree. The small angle generator can also be used with an index table that can divide one circle into 1440 angles. The combined system can generate any angle over 360 degrees to an accuracy of 0.11 seconds.

저손실 융착접속을 이용한 광자결정 광섬유 간섭계

안진수,김길환,이관일,이경식,이상배,Ahn, Jin-Soo,Kim, Gil-Hwan,Lee, Kwan-Il,Lee, Kyung-Shik,Lee, Sang-Bae 한국광학회 2010 한국광학회지 Vol.21 No.5

본 논문에서는 포토닉 밴드갭 광섬유(Photonic Bandgap Fiber: PBGF) 사이에 중공광섬유(Hollow Optical Fiber: HOF)를 융착 접속시켜 만든 광섬유 간섭계와 넓은 모드 면적을 가지는 광자결정 광섬유(Large Mode Area-Photonic Crystal Fiber: LMA-PCF)사이에 HOF를 융착접속시켜 만든 광섬유 간섭계의 온도 및 스트레인에 대한 광학적 특성을 분석하였다. PBGF 또는 LMA-PCF와 HOF의 융착접속시 광섬유내 공기구멍을 최대한 유지하도록 융착조건을 최적화하여 접속 손실을 줄였다. PBGF와 HOF로 구성된 광섬유 간섭계의 온도 및 스트레인에 대한 민감도는 각각 15.4 pm/$^{\circ}C$와 0.24 pm/${\mu}\varepsilon$으로 측정되었으며, LMA-PCF와 HOF로 구성된 광섬유 간섭계의 온도 및 스트레인에 대한 민감도는 각각 17.4 pm/$^{\circ}C$와 0.2 pm/${\mu}\varepsilon$으로 측정되었다. We report temperature and strain sensing characteristics of two kinds of in-line fiber interferometers. One interferometer consists of a section of Hollow Optical Fiber(HOF) spliced between two Photonic Bandgap Fibers(PBGF) and the other is built by splicing a section of HOF between two Large Mode Area-Photonic Crystal Fibers(LMA-PCF). To minimize the splice losses, we carefully optimized the heating time and arc current of the splicer so as not to collapse the air holes of the fiber. It is found that the first interferometer has a temperature sensitivity of 15.4 pm/$^{\circ}C$ and a strain sensitivity of 0.24 pm/${\mu}\varepsilon$. The other interferometer exhibits a temperature sensitivity of 17.4 pm/$^{\circ}C$ and a strain sensitivity of 0.2 pm/${\mu}\varepsilon$.