• Title/Summary/Keyword: Optical Interferometer

Search Result 614, Processing Time 0.025 seconds

High Precision Measurement of 3D Profile Using Confocal Differential Heterodyne Interferometer

  • Kim Taejoong;Lee SeungWoo;Gweon Dae-Gab
    • Journal of the Optical Society of Korea
    • /
    • v.9 no.1
    • /
    • pp.22-25
    • /
    • 2005
  • The differential heterodyne interferometer (DHI) is suitable for precise measurement of step height and line width, since its differential configuration can significantly reduce disturbances from the environment [1,2]. Like most phase measuring interferometers, however, the DHI is limited, in that it can obtain only the phase from 0 to 2π, because of the sinusoidal nature of the optical interference involved. Thus, the measurable step height is limited to one quarter of the wavelength of the light source. This study describes a confocal differential heterodyne interferometer (CDHI) for measuring step heights of several micrometers, with a high resolution and line width with high repeatability. The CDHI has a simple structure and rapid measurement speed.

VISUALIZATION OF INTERNAL DEFECTS IN PLATE-TYPE NUCLEAR FUEL BY USING NONCONTACT OPTICAL INTERFEROMETRY

  • Park, Seung-Kyu;Park, Nak-Gyu;Baik, Sung-Hoon;Kang, Young-June
    • Nuclear Engineering and Technology
    • /
    • v.45 no.3
    • /
    • pp.361-366
    • /
    • 2013
  • An imaging technique to visualize the internal defects in a plate-type nuclear fuel specimen was developed by using an active optical interferometer for a nondestructive quality inspection. A periodic thermal wave having a sinusoidal intensity pattern induced a periodical strain variation for the specimen. The varying strain image was acquired using an optical laser interferometer. The strain distribution over the internal defects will be distorted in an acquired strain image because a part of the thermal wave will be reflected from these defects during propagation. In this paper, internal defects were efficiently visualized by sequentially accumulating the extracted defect components. The experimental results confirmed that the developed visualization system can be a valuable tool to detect the internal defects in plate-type nuclear fuel.

Pulse Compression by the Nonlinear Silicon Fabry-Perot Interferometer (실리콘 비선형 Fabry-Perot 간섭계를 이용한 광펄스 변조와 축약)

  • 김달현;이재형;장준성
    • Korean Journal of Optics and Photonics
    • /
    • v.1 no.1
    • /
    • pp.40-45
    • /
    • 1990
  • Optical pulse compression in a high finesse nonlinear Fahry-Perot interferometer made hy a silicon is ohserved. The optical pulse compression and moclul,ltion in a such nonlinear Fabry-Perot interferometer is due to the refractive index change of the silicon hy absorbing the incicknt pulse and generating electron-hole pairs. The pulse is compressed to liS of width of the IIlcicient pulse. And the experimental results are consistent with the results of computer simulation.lation.

  • PDF

Measurement of the effective optical thickness of optical media using intermode beat interferometer scheme (두 종모드 레이저 빛 사이의 맥놀이 신호를 이용한 간섭계에 의한 유효 광학 두께 측정)

  • 윤신영;조규만;이용산
    • Korean Journal of Optics and Photonics
    • /
    • v.8 no.1
    • /
    • pp.26-30
    • /
    • 1997
  • A wide dynamic range heterodyne interferometer scheme using intermode beat between a stabilized, dual frequency He-Ne laser beam has been applied for a measurement of optical thickness of an optical medium. Resolution of the optical thickness measurement is about $\pm$ 1.74 ${\mu}{\textrm}{m}$. Using this technique, we are able to determine the optical thickness of an organic dye film. We also obtain a map of the optical thickness variations over a surface of the film

  • PDF

All-Optical Binary Full Adder Using Logic Operations Based on the Nonlinear Properties of a Semiconductor Optical Amplifier

  • Kaur, Sanmukh;Kaler, Rajinder-Singh;Kamal, Tara-Singh
    • Journal of the Optical Society of Korea
    • /
    • v.19 no.3
    • /
    • pp.222-227
    • /
    • 2015
  • We propose a new and potentially integrable scheme for the realization of an all-optical binary full adder employing two XOR gates, two AND gates, and one OR gate. The XOR gate is realized using a Mach-Zehnder interferometer (MZI) based on a semiconductor optical amplifier (SOA). The AND and OR gates are based on the nonlinear properties of a semiconductor optical amplifier. The proposed scheme is driven by two input data streams and a carry bit from the previous less-significant bit order position. In our proposed design, we achieve extinction ratios for Sum and Carry output signals of 10 dB and 12 dB respectively. Successful operation of the system is demonstrated at 10 Gb/s with return-to-zero modulated signals.

Point-diffraction interferometer for 3-D profile measurement of light scattering rough surfaces (광산란 거친표면의 고정밀 삼차원 형상 측정을 위한 점회절 간섭계)

  • 김병창;이호재;김승우
    • Korean Journal of Optics and Photonics
    • /
    • v.14 no.5
    • /
    • pp.504-508
    • /
    • 2003
  • We present a new point-diffraction interferometer, which has been devised for the three-dimensional profile measurement of light scattering rough surfaces. The interferometer system has multiple sources of two-point-diffraction and a CCD camera composed of an array of two-dimensional photodetectors. Each diffraction source is an independent two-point-diffraction interferometer made of a pair of single-mode optical fibers, which are housed in a ceramic ferrule to emit two spherical wave fronts by means of diffraction at their free ends. The two spherical wave fronts then interfere with each other and subsequently generate a unique fringe pattern on the test surface. A He-Ne source provides coherent light to the two fibers through a 2${\times}$l optical coupler, and one of the fibers is elongated by use of a piezoelectric tube to produce phase shifting. The xyz coordinates of the target surface are determined by fitting the measured phase data into a global model of multilateration. Measurement has been performed for the warpage inspection of chip scale packages (CSPs) that are tape-mounted on ball grid arrays (BGAs) and backside profile of a silicon wafer in the middle of integrated-circuit fabrication process. When a diagonal profile is measured across the wafer, the maximum discrepancy turns out to be 5.6 ${\mu}{\textrm}{m}$ with a standard deviation of 1.5 ${\mu}{\textrm}{m}$.

Digital watermarking using binary phase hologram and optical interferometer (이진 위상 홀로그램과 광학적 간섭계를 이용한 디지털 워터마킹)

  • 김병열;서동환;조규보;신창목;김수중;김철수
    • Korean Journal of Optics and Photonics
    • /
    • v.14 no.4
    • /
    • pp.377-382
    • /
    • 2003
  • We propose a new optical watermarking method, which can protect the copyright of digital data, using a binary phase hologram and a Mach-Zehnder interferometer. Using a simulated annealing algorithm, the binary phase hologram of the mark image to be hidden is designed. We obtained a watermarked image by linearly superposing the hologram, which is the watermark, in the original image. The extraction processing of the mark image from the watermarked image is achieved by placing the phase-modulated watermarked image on a LCD in one path and the phase-modulated original image on another LCD in the other path in the Mach-Zehnder interferometer. The mark image was obtained by inverse Fourier transforming the phase modulated interference intensity. We confirmed that the proposed method is robust for the cropped images through computer simulation, and we implemented it optically using LCDs which are phase modulation devices.

Single Photon Interference Experiments in a Sagnac-type Mach-Zehnder Interferometer (Sagnac 형태로 변형된 Mach-Zehnder 간섭계를 이용한 단일광자 간섭실험)

  • Um, Jayoon;Kim, Yong Soo;Kim, Heonoh
    • Korean Journal of Optics and Photonics
    • /
    • v.23 no.2
    • /
    • pp.71-76
    • /
    • 2012
  • A Sagnac-type Mach-Zehnder interferometer(SMZI) is a very stable instrument with respect to phase drift because all optical paths can share common optical components. We have observed very stable interference fringes in single photon interference experiments with an extremely attenuated laser beam, and with heralded single photons prepared from polarization correlated photon pairs in type-II spontaneous parametric down-conversion. The phase stability is measured to be about ${\pm}0.18$ rad for the SMZI, in contrast, conventional MZI showed the phase fluctuation of around ${\pm}1.02$ rad.

Systematic error calibration of 2-axis lateral shearing interferometer (2축 층밀리기 간섭계의 계통오차 보정)

  • 김승우;이혁교
    • Korean Journal of Optics and Photonics
    • /
    • v.13 no.2
    • /
    • pp.98-104
    • /
    • 2002
  • We present a new self-calibration method to remove the systematic error of a 2-axis lateral shearing interferometer that has been specially designed for optical testing of aspheric optics. The method takes multiple measurements by rotating the test optics and extracts the systematic error by fitting the measured wavefronts into the Zernike polynomials. The method works with arbitrary azimuthal angles for test optics rotation, which offers an advantage of correcting the error induced by the non-orthogonality of the two axes of wavefront shearing as well as the error caused by the optical components of the interferometer system itself.

Measurements of Nonlinearity in homodyne interferometer (Homodyne interferometer의 Non I inear ity 측정)

  • 김종윤;엄태봉;정규원;최태영;이건희
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 2000.11a
    • /
    • pp.55-59
    • /
    • 2000
  • Nonlinearity is one of the primary causes of error in precision length measurement using laser interferometer. It arises periodically. The periodical nonlinearity usually ranges from sub-naometre to several namertres. In the homodyne interferometer, it results from a number of factors including polarization mixing, imperfect optical clement, unequal gain of detectors, misalignment of axes between input beam and beam splitter. In this paper, we described a method for measuring and compensating the nonlinearity of homodyne interferometer using the elliptical least-square fitting technique associated with electric method and experimental results in one frequency polarization interferometer.

  • PDF