• Title/Summary/Keyword: Tuning Fork Feedback System

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A Study for a Near-Field Microwave Microscope Using a Tuning Fork Distance Control System in liquid Environment (튜닝폭 거리조절 센서를 이용한 근접장 마이크로파 현미경의 수중 측정을 위한 연구)

  • Kim, Song-Hui;Yoo, Hyung-Keun;Babajanyan, Arsen;Kim, Jong-Chul;Lee, Kie-Jin
    • Journal of the Korean Society for Nondestructive Testing
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    • v.27 no.4
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    • pp.345-353
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    • 2007
  • We have obtained a topographical image nondestructively for a Cu thin film in liquid using a near-field scanning microwave microscope (NSMM), its operating frequency was 3.5 to 5.5 GHz. We have kept a distance of 10 nm between tip and sample using a quartz tuning fork shear force feedback system. As an end of tip was attached to one prong of the quartz tuning fork has a length of 2 mm, the only tip of tuning fork was immersed in water tank. A loss cause by evaporation in water tank is regulated with actuator was connected to a supplementary tank. Moreover, using a revise program of LabView, we could increase the accuracy of a measurement in liquid.

Optical and Mechanical Characteristics of NF System and NF Gap Control (근접장 광학계의 광학적 및 기계적 특성 분석과 근접장 간격제어)

  • Oh, Hyeong-Ryeol;Lee, Jun-Hee;Gweon, Dae-Gab;Kim, Soo-Kyung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.06a
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    • pp.1528-1532
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    • 2000
  • The conventional optics and near field optics are compared numerically in the view points of the spot size and propagation characteristics. The decaying characteristics of near field light require the optics to access the object within several tens of nanometers. Therefore the gap control is one of the main issues in the near field optics area. In this paper the gap control is done by using the shear force of the NF(Near Field) probe and the characteristics are examined. The probe is modeled as a 2'nd order mass-spring-damper system driven by a harmonic force. The primary cause of the decrease in vibration amplitude is due to the damping force - shear force - between the surface and the probe. Using the model, damping constant and resonance frequency of the probe is calculated as a function of probe-sample distance. Detecting the amplitude and phase shift of the NF probe attached to the high Q-factor piezoelectric tuning fork, we can control the position of the NF probe about 0 to 50nm above the sample. The feedback signal to regulate the probe-sample distance can be used independently for surface topography imaging. 3-D view of the shear force image of a testing sample with the period of $1{\mu}m$ will be shown.

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A study on the feedback control system for near field scanning optical microscope based on the tuning fork oscillator (수정 진동자를 이용한 근접장광학계 (Near-Field Scanning Optical Microscope) 제작 및 특성연구)

  • 윤선현
    • Korean Journal of Optics and Photonics
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    • v.10 no.4
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    • pp.267-272
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    • 1999
  • We attached a fiber tip on the branch of a quartz crystal oscillator in order to make a feedback control system for near field optical microscope. The electrical impedance of the quartz crystal oscillator depends on the distance between the surface of the sample and the tip caused by the surface damping. Using this method, we can directly monitor the distance between the sample and the tip without inserting extra beam which might give extra optical noise. We characterize the XY scanning resolution and the amplitude of the vibrating tip and the Z-dependent decay of the evanescent wave.

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Concentration of Sodium Chloride Solutions Sensing by Using a Near-Field Microwave Microprobe (비접촉 근접장 마이크로파 현미경을 이용한 NaCl 용액의 농도 측정)

  • Kim, Song-Hui;Yoon, Young-Woon;Babajanyan, Arsen;Kim, Jong-Chul;Lee, Kie-Jin
    • Journal of the Korean Society for Nondestructive Testing
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    • v.27 no.1
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    • pp.23-30
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    • 2007
  • We observed the NaCl concentration of solutions using a near-field microwave microprobe(NFMM). Instead of the usual technique, we take advantage of the noncontact evaluation capabilities of a NFMM. A NFMM with a high Q dielectric resonator allows observation of small variations of the permittivity due to changes in the NaCl concentration. The changes of NaCl concentration due to a change of permittivity of the NaCl solution were investigated by measuring the microwave reflection coefficient $S_{11}$ of the resonator. The NaCl sensor consisted of a dielectric resonator coupled to a probe tip at an operating frequency of about f=4 GHz. The change of the NaCl concentration is directly related to the change of the reflection coefficient due to a near field electromagnetic interaction between the probe tip and the NaCl solution. In order to determine the probe selectivity, we measured a mixture solution of NaCl and glucose.