• Title/Summary/Keyword: Lateral Resolution

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Design of an Endoscopic Microscope Objective Lens Composed of Flexible Fiber Bundle and Gradient-index with a High Resolution and a Minimally-Invasive Outer Diameter (광섬유 다발과 Gradient-index Lens가 결합된 고 분해능 및 최소침습 직경의 공초점 내시 현미경 대물렌즈의 설계)

  • Jang, Sun-Young;Rim, Cheon-Seog
    • Korean Journal of Optics and Photonics
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    • v.19 no.2
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    • pp.87-94
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    • 2008
  • We present a new design for an endoscope objective lens composed of a lexible fiber bundle with 30,000 core, and a gradient-index (GRIN) objective lens with an optical adaptor. The characteristic of this objective lens is to be minimally-invasive to be able to insert easily in the internal organs of live animals. The GRIN lens has a small diameter and a very simple construction, which is selected with the diameter of 1.0 mm and numerical aperture of 0.5 to achieve a minimally-invasive outer diameter and a high resolution. The resultant designed lens shows the performance as follows; a lateral resolution of 1.63 um and diameters of 100% encircled energy of $0.3\;{\mu}m$ and $0.83\;{\mu}m$ for the on-axis and the off-axis image point, respectively. Also, we can present a cheap solution with a lateral resolution of 1.74 um and diameters of 100% encircled energy of $1.10\;{\mu}m$ and $2.84\;{\mu}m$ for the on-axis and the off-axis image point, respectively.

An Experimental Study of the Synthetic Sinc Wave in Ultrasonic Imaging (초음파 의료 영상에서 합성 Sinc 음장 집속방법의 실험적 고찰)

  • 이광주;정목근
    • Journal of Biomedical Engineering Research
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    • v.23 no.3
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    • pp.243-251
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    • 2002
  • Synthetic zinc wave employs Pulsed plane wave as transmit beam with linear time delay curve. The received echoes in different transmit directions at different transmit times are superposed at imaging Points with Proper time delay compensation using synthetic focusing scheme. This scheme. which uses full aperture in transmit, obtains a high SNR image, and also features high lateral resolution by using two way dynamic focusing at all imaging depths. In this Paper, we consider the Problems in realization of synthetic zinc wave. Also. we have applied the scheme to obtain phantom and in-vivo images using a linear array of 5 MHz. In phantom test. experimental images show high resolution over a more extended imaging depth than conventional fixed Point transmit and receive dynamic focusing schemes In-vivo images show that the resolution could not overcome conventional focusing systems because of motion blurring and(or) aberration of tissue. but the frame rate tan be increased by a factor of more than 5 compared to conventional focusing schemes. with competitive resolution at all imaging depths .

Deconvolution Method for TOFD Technique (TOFD 법에서의 근거리 분해능 향상에 관한 연구)

  • Lee, Sun-Heum;Kim, Sun-Hyoung;Kong, Yong-Hae;Lee, Weon-Heum
    • Journal of the Korean Society for Nondestructive Testing
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    • v.19 no.6
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    • pp.420-425
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    • 1999
  • Time of flight diffraction(TOFD) method is used in nondestructive tests of piping and pressure vessels because of its advantages over a pulse echo technique: its speed, objectivity, repeatability and its insensitivity to specimen surface conditions and discontinuity orientation. But it is the one of weak points in TOFD method that it has the dead zone in sub-surface resolution induced by lateral waves. We solved the dead-zone problem near the sub-surface by using the deconvolution method and the developed ultrasonic testing system showed high performance.

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A Study on the Fabrication of the Lateral Accelerometer using SOG(Silicon On Glass) Process (SOG(Silicon On Glass)공정을 이용한 수평형 미소가속도계의 제작에 관한 연구)

  • Choi, Bum-Kyoo;Chang, Tae-Ha;Lee, Chang-Kil;Jung, Kyu-Dong;Kim, Jong-Pal
    • Journal of Sensor Science and Technology
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    • v.13 no.6
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    • pp.430-435
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    • 2004
  • The resolution of the accelerometer, fabricated with MEMS technology is mainly affected by mechanical and electrical noise. To reduce mechanical noise, we have to increase mass of the structure part and quality factor related with the degree of vacuum packaging. On the other hand, to increase mass of the structure part, the thickness of the structure must be increased and ICP-RIE is used to fabricate the high aspect ratio structure. At this time, footing effect make the sensitivity of the accelerometer decreasing. This paper presents a hybrid SOG(Silicon On Glass) Process to fabricate a lateral silicon accelerometer with differential capacitance sensing scheme which has been designed and simulated. Using hybrid SOG Process, we could make it a real to increase the structural thickness and to prevent the footing effect by deposition of metal layer at the bottom of the structure. Moreover, we bonded glass wafer to structure wafer anodically, so we could realize the vacuum packaging at wafer level. Through this way, we could have an idea of controlling of quality factor.

Design of Ultrasound Dynamic Focusing Systems (초음파 다이나믹 집속 시스템의 설계)

  • 김진하;김청월
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.21 no.4
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    • pp.65-71
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    • 1984
  • The design formular of optical focusing systems cannot be applied to ultrasonic B scanners, which use broadband pulses instead of continuous wave. In this paper, a calculation method is studied for analyzing the propagation of ultrasonic broadband pulse excited by ultrasonic array transducers. Using the results, seveial design parameters such as the number of transducer elements, delay time, and the focal point are determined to obtain high resolution in the ultrasonic dynamic focusing system. A dynamic focusing system with low-noise switching characteristics; which attains lateral resolution of 2-3mm all along the axial direction up to 18 cm with a 3.5 MHz linear array transducer, was implemented.

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CPT-based lateral displacement analysis using p-y method for offshore mono-piles in clays

  • Kim, Garam;Park, Donggyu;Kyung, Doohyun;Lee, Junhwan
    • Geomechanics and Engineering
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    • v.7 no.4
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    • pp.459-475
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    • 2014
  • In this study, a CPT-based p-y analysis method was proposed for the displacement analysis of laterally loaded piles. Key consideration was the continuous soil profiling capability of CPT and cone resistance profiles that do not require artificial assumption or simplification for input parameter selection. The focus is on the application into offshore mono-piles embedded in clays. The correlations of p-y function components to the effective cone resistance were proposed, which can fully utilize CPT measurements. A case example was selected from the literature and used to validate the proposed method. Various parametric studies were performed to examine the effectiveness of the proposed method and investigate the effect of property profile and its depth resolution on the p-y analysis. It was found that the calculation could be largely misleading if wrongly interpreted sub-layer condition or inappropriate resolution of input soil profile was involved in the analyses. It was also found that there is a significant influence depth that dominates overall load response of pile. The soil profile and properties within this depth range affect most significantly calculated load responses, confirming that the soil profile within this depth range should be identified in more detail.

Fabrication of an On System based on an Optical Delay line with Cylindrical PZT (실린더형 압전소자 광지연선을 이용한 광 간섭형 단층촬영(OCT) 시스템 제작)

  • Park, Sung-Jin;Kim, Young-Kwan;Kim, Yong-Pyung
    • Korean Journal of Optics and Photonics
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    • v.17 no.2
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    • pp.159-164
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    • 2006
  • We demonstrate a compact optical coherence tomography(OCT) system based on the optical fiber delay line controlled by a cylindrical piezo-electric transducer(PZT). An 18-m length of single mode fiber is wrapped under constant tension around a PZT. Approximately 134 windings are used. Wraps of the long length of fiber allow the small expansion of the PZT to be magnified to an optical path length delay of 0.78 m. The OCT system shows characteristics for 2-dimensional imaging, exhibiting 96.9dB of signal-to-noise ratio(SNR), $18.6{\pm}0.5\;{\mu}m$ of axial resolution, and $5\;{\mu}m$ of lateral resolution with samples.

Terahertz Nondestructive Time-of-flight Imaging with a Large Depth Range

  • Kim, Hwan Sik;Kim, Jangsun;Ahn, Yeong Hwan
    • Current Optics and Photonics
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    • v.6 no.6
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    • pp.619-626
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    • 2022
  • In this study, we develop a three-dimensional (3D) terahertz time-of-flight (THz-TOF) imaging technique with a large depth range, based on asynchronous optical sampling (ASOPS) methods. THz-TOF imaging with the ASOPS technique enables rapid scanning with a time-delay span of 10 ns. This means that a depth range of 1.5 m is possible in principle, whereas in practice it is limited by the focus depth determined by the optical geometry, such as the focal length of the scan lens. We characterize the spatial resolution of objects at different vertical positions with a focal length of 5 cm. The lateral resolution varies from 0.8-1.8 mm within the vertical range of 50 mm. We obtain THz-TOF images for samples with multiple reflection layers; the horizontal and vertical locations of the objects are successfully determined from the 2D cross-sectional images, or from reconstructed 3D images. For instance, we can identify metallic objects embedded in insulating enclosures having a vertical depth range greater than 30 mm. For feasible practical use, we employ the proposed technique to locate a metallic object within a thick chocolate bar, which is not accessible via conventional transmission geometry.

A Study on the Effectiveness of Hand Sanitizer compared to Conventional Ultrasound Gel during Ultrasound Examination (초음파검사 시 기존 초음파젤과 비교한 손소독제의 유용성 연구)

  • Sun-Youl Seo;Jin-Ok Lee;Young-Ran Kim
    • Journal of the Korean Society of Radiology
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    • v.17 no.6
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    • pp.957-964
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    • 2023
  • This study focused on hand sanitizer as a medium that can replace ultrasonic gel, which is vulnerable to contamination by bacteria that reside on the hand. Hand sanitizer produces a strong sterilization effect from germs resident on the hands through different sterilization principles depending on the ingredients. Select products of gel type, cream type, and foam type, except for liquid type with low viscosity, and ultrasonically apply one 62% ethanol gel type and one cream type, one benzalkonium chloride 0.066% cream type and one foam type, respectively. Using ATS-539 as a medium, image evaluation was performed on the axial and lateral resolution and penetration depth, and the presence or absence of an air layer between the probe and the phantom. As a result, in the evaluation of the axial and lateral resolution and the depth of penetration, all four experimental groups met the evaluation criteria. However, in the case of the foam type, although it was suitable for the evaluation criteria of resolution and penetration depth, dark shadows appeared on both sides except for the center of observation during image evaluation. Through this experiment, it was possible to confirm the possibility that the remaining three types of hand sanitizers except the foam type could replace the ultrasonic gel.

Heat Treatment of Carbonized Photoresist Mask with Ammonia for Epitaxial Lateral Overgrowth of a-plane GaN on R-plane Sapphire

  • Kim, Dae-sik;Kwon, Jun-hyuck;Jhin, Junggeun;Byun, Dongjin
    • Korean Journal of Materials Research
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    • v.28 no.4
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    • pp.208-213
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    • 2018
  • Epitaxial ($11{\bar{2}}0$) a-plane GaN films were grown on a ($1{\bar{1}}02$) R-plane sapphire substrate with photoresist (PR) masks using metal organic chemical vapor deposition (MOCVD). The PR mask with striped patterns was prepared using an ex-situ lithography process, whereas carbonization and heat treatment of the PR mask were carried out using an in-situ MOCVD. The heat treatment of the PR mask was continuously conducted in ambient $H_2/NH_3$ mixture gas at $1140^{\circ}C$ after carbonization by the pyrolysis in ambient $H_2$ at $1100^{\circ}C$. As the time of the heat treatment progressed, the striped patterns of the carbonized PR mask shrank. The heat treatment of the carbonized PR mask facilitated epitaxial lateral overgrowth (ELO) of a-plane GaN films without carbon contamination on the R-plane sapphire substrate. Thhe surface morphology of a-plane GaN films was investigated by scanning electron microscopy and atomic force microscopy. The structural characteristics of a-plane GaN films on an R-plane sapphire substrate were evaluated by ${\omega}-2{\theta}$ high-resolution X-ray diffraction. The a-plane GaN films were characterized by X-ray photoelectron spectroscopy (XPS) to determine carbon contamination from carbonized PR masks in the GaN film bulk. After $Ar^+$ ion etching, XPS spectra indicated that carbon contamination exists only in the surface region. Finally, the heat treatment of carbonized PR masks was used to grow high-quality a-plane GaN films without carbon contamination. This approach showed the promising potential of the ELO process by using a PR mask.