• 제목/요약/키워드: grating length

검색결과 114건 처리시간 0.024초

레이저의 간섭무늬를 이용한 리니어 엔코더에 관한 연구 (High resolution Linear Encoder Using Interference Fringe)

  • 박윤창
    • 한국생산제조학회지
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    • 제8권4호
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    • pp.130-135
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    • 1999
  • The main scale of linear encoder greatly effects on the precision of displacement measurement. Especially when needing the long range measurement the length of main scale should be increased accordingly. In this paper we propose a linear encoder that uses laser interference pattern as main scale for long range measurement. The linear encoder is similar to Michelson interferometer excepting that the reference mirror is tilted so as to obtain interference fringe pattern and a grating panel is attached on a quadratic photo diodes. Four kinds of grating having phase difference of 0. $\pi$/4, $\pi$/2, 3$\pi$/4 are arranged on the panel. The experimental results show that signals of quadratic photo diode A, B, {{{{ {-}atop {A } }}}} and {{{{ {- } atop {B } }}}} are cosine wavelike and successive signals have phase difference of $\pi$/4 each other. So the proposed method can achieve improved measurement resolution.

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광기록 정보저장용 Diffractive Optical Head 제작 연구 (Fabrication technology of the Diffractive Optical Head for optical recoding information storage)

  • 한기평;김태엽;손영준;김약연;백문철
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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    • pp.992-993
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    • 2002
  • We have fabricated the diffractive optical head(DOH) for optical pick up, which one adaptable to a optical recoding information storage. DOH consists of a focusing grating coupler(FGC) and a solid immersion Jens(SIL). FGC is device that the light converge into a focus by surface lattice. FGC have been studied as a potential application of pick up head for the information storage. In this study, FGC was designed and fabricated to make focus near to possible diffraction limit. We also fabricated recording head combined with SIL. The focus was measured in the range of $1.1{\mu}m$ as near to possible diffraction limit in the FGC having a focusing length of $600{\mu}m$ and a lattice area of 500 * $500{\mu}m$.

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3-Dimensionally Integrated Planar Optics for 100 Gb/s Optical Packet Address Detection

  • Song, Seok-Ho;Lee, El-Hang
    • ETRI Journal
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    • 제17권2호
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    • pp.1-10
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    • 1995
  • We propose a novel planar optical interconnection scheme for 100 Gb/s optical packet address detection, which consists of waveguide grating couplers and a diffractive microlens integrated on a glass substrate 3-dimensionally. Length and duty cycle of the grating couplers have been determined on the bases of the ray-optic propagation-mode analysis in a slab waveguide and of the rigorous coupled-wave diffraction analysis for out-coupled radiation-modes. The 3-dimensionally integrated planar optics makes it possible to connect each address bit-signals of $TE_ 0-waveguide$ mode to the detector with a power uniformity of 6.4 % and a total coupling efficiency of 72.3 %.

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The Effects of Various Apodization Functions on the Filtering Characteristics of the Grating-Assisted SOI Strip Waveguides

  • Karimi, Azadeh;Emami, Farzin;Nozhat, Najmeh
    • Journal of the Optical Society of Korea
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    • 제18권2호
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    • pp.101-109
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    • 2014
  • In this paper, four apodization functions are proposed for silicon-on-insulator (SOI) strip waveguides with sidewall-corrugated gratings. The effects of apodization functions on the full width at half maximum (FWHM), the side-lobe level, and the reflectivity of the reflection spectrum are studied using the coupled-mode theory (CMT) and the transfer-matrix method (TMM). The results show that applying proposed apodization functions creates very good filtering characteristics. Among investigated apodized waveguides, the apodization functions of Polynomial and z-power have the best performance in reducing side-lobes, where the side-lobe oscillations are entirely removed. Four functions are also used for precise adjustment of the bandwidth. Simulation results show that the minimum and maximum values of the FWHM are 0.74 nm and 8.48 nm respectively. In some investigated functions, changing the apodization parameters decreases the reflectivity which is compensated by increasing the grating length.

Anchoring Properties in Photo-aligned Periodic Domains for Wide-viewing Liquid Crystal Displays

  • Yu, Chang-Jae;Park, Jae-Hong;Lee, Sin-Doo
    • Journal of Information Display
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    • 제4권1호
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    • pp.24-28
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    • 2003
  • We studied the anchoring properties in photo-aligned periodic domains of liquid crystals (LCs) in an alternating homeotropic and hybrid geometry. In this geometry, the surface anchoring energy was determined in using the director-distorted length of the LC near domain boundary, calculated in a linear approximation of the director profile within the continuum theory. The measurements were made using the LC diffraction grating with the phase profile in the form of a trapezoid.

광 부호 분할 다중접속 네트워크를 위한 파장/시간 2차원 코드의 새로운 부호기/복호기 (New Encoder/Decoder with Wavelength/Time 2-D Codes for Optical CDMA Network)

  • 황유모
    • 전기학회논문지
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    • 제58권5호
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    • pp.1035-1040
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    • 2009
  • We propose a new encoder/decoders based on an tune able wavelength converter(TWC) and an arrayed waveguide grating(AWG) router for large capacity optical CDMA networks. The proposed encoder/decoder treats codewords of wavelength/time 2-D code simultaneously using the dynamic code allocation property of the TWC and the cyclic property of the AWG router, and multiple subscribers can share the encoder/decoder in networks. Feasibility of the structure of the proposed encoder/decoder for dynamic code allocation is tested through simulations using two wavelength/time 2-D codes, which are the generalized multi-wavelength prime code(GMWPC) and the generalized multi-wavelength Reed-Solomon code(GMWRSC). Test results show that the proposed encoder/decoder can increase the channel efficiency not only by increasing the number of simultaneous users without any multiple-access interference but by using a relatively short length CDMA codes.

A Transverse Load Sensor with Reconfigurable Measurement Accuracy Based on a Microwave Photonic Filter

  • Chen, Han;Li, Changqing;Min, Jing
    • Current Optics and Photonics
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    • 제2권6호
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    • pp.519-524
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    • 2018
  • We propose a transverse load sensor with reconfigurable measurement accuracy based on a microwave photonic filter in the $K_u$ band, incorporating a polarization-maintaining fiber Bragg grating. A prototype sensor with a reconfigurable measurement accuracy tuning range from 6.09 to 9.56 GHz/(N/mm), and corresponding minimal detectable load range from 0.0167 to 0.0263 N/mm, is experimentally demonstrated. The results illustrate that up to 40% manufacturing error in the grating length can be dynamically calibrated to the same corresponding measurement accuracy for the proposed transverse load sensor, by controlling the semiconductor optical amplifier's injection current in the range of 154 to 419 mA.

Talbot Interferometry for Measuring the Focal Length of a Lens without Moiré Fringes

  • Lee, Sukmock
    • Journal of the Optical Society of Korea
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    • 제19권2호
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    • pp.165-168
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    • 2015
  • A simple method to determine the focal length of a lens using the Talbot image is presented. This method uses only one grating, requiring neither Moir$\acute{e}$ fringe analysis nor the angle between the gratings. The original Fourier transform was used to access the spectrum beyond the limitation set of the usual fast Fourier transform to determine the (de)magnification accurately enough to be used for the focal length. A set of Talbot images simulated numerically with the Fresnel diffraction integral was used to demonstrate the method. For focal lengths between 5550 mm and 5650 mm, the mean difference between the focal lengths determined from the Talbot images and the true values was 3.3 mm with the standard deviation of the difference being 3.8 mm. The true focal lengths can be recovered with an accuracy of 0.06%.

광섬유 브래그 격자 센서를 이용한 보 구조물의 3차원 형상 추정 (Three-Dimensional Shape Estimation of Beam Structure Using Fiber Bragg Grating Sensors)

  • 이진혁;김헌영;김대현
    • 대한기계학회논문집A
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    • 제39권3호
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    • pp.241-247
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    • 2015
  • 교량이나 배관과 같이 긴 길이의 구조물은 처짐 및 변형이 발생하기 쉽다. 이러한 구조물의 건전성 감시를 위해서는 국부적인 물리량 측정뿐만 아니라 전체의 형상 감시가 필요하다. 광섬유 브래그 격자(Fiber Bragg Grating; FBG) 센서는 광섬유에 다수의 센서 적용이 가능하여 대형 구조물 감시에 효과적이다. 본 연구에서는 FBG를 이용하여 구조물의 다점에서 변형률을 측정하고, 이를 바탕으로 구조물 전체의 형상 추정을 위한 연구를 수행하였다. 구조물의 정확한 감시가 가능하도록 3차원의 형상 추정을 연구하고 실험적 검증을 수행하였다. 실험 결과 구조물의 변형에 따른 형상 변화의 추정이 가능함을 확인하였고, 추가로 특정 위치에서의 처짐량을 실제 마이크로미터로 측정한 값과 예측된 값을 비교하여 검증하였다.

광섬유 브래그 격자의 제작 방법에 따른 기계적 강도 특성 (Mechanical Strength Characteristics of Fiber Bragg Gratings with Fabrication Process)

  • 박상오;김천곤;강동훈
    • Composites Research
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    • 제18권1호
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    • pp.16-22
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    • 2005
  • 광섬유 브래그 격자를 이용한 모니터링 연구는 시편 단위의 연구뿐만 아니라 최근 2차 구조물을 비롯하여 주 구조물로까지 그 적용 영역이 점차 확대되고 있어 신뢰성에 대한 검증이 더욱 중요해지고 있다. 본 연구에서는 광섬유 브래그 격자의 제작 방법과 반사율에 따른 기계적 강도 특성을 다양한 격자의 길이에 대해 고찰하였다. 인장 시험을 통해 광섬유는 피복 제거만으로도 약 $50\%$ 정도의 강도 저하가 발생하며 피복 제거 방법에 따라 감소량이 달라짐을 확인하였다. 피복이 제거된 광섬유에 브래그 격자를 형성하게 될 경우 반사율과 격자의 길이와는 무관하게 약 $55\%$ 정도의 강도 저하가 발생하였다. 반면, 반사율이 증가할수록 강도의 분산도는 상대적으로 증가하였다.