• Title, Summary, Keyword: Optical Triangulation

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The Development of Laser Displacement Sensor using CCD&Optical triangulation technique (CCD 와 Optical triangulation Technique을 이용한 Laser Displacement Sensor 의 개발)

  • 박희재;이동성;유인상;유영기
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.47-50
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    • 2000
  • Optical triangulation is one of the most common methods for acquiring range data. Using this method. We have developed a new type of Laser Displacement Sensor. We used Area CCD instead of linear CCD and PSD (Position Sensitive Detector). And we have developed the robust algorithm for increasing the accuracy and used USB instead of RS-232C for increasing speed. We present results that demonstrate the validity of our method using optical triangulation technique, Area CCD, and USB.

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Design of a non-contact type displacement measurement system based on optical triangulation method (광삼각법에 의한 비접촉식 변위측정계의 설계)

  • 이재윤;김승우
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.16 no.6
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    • pp.1030-1035
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    • 1992
  • This paper presents a non-contact type displacement sensor designed based on optical triangulation method. The optical principles of the sensor are described in detail with aids of paraxial geometric optics. A prototype sensor is designed and fabricated by using modern optoelectronic hardware. Its measuring performances are evaluated and discussed through a series of calibration processes.

Design & Analysis of an Error-reduced Precision Optical Triangulation Probes (오차 최소화된 정밀 광삼각법 프로브의 해석 및 설계)

  • Kim, Kyung-Chan;Oh, Se-Baek;Kim, Jong-Ahn;Kim, Soo-Hyun;Kwak, Yoon-Keun
    • Proceedings of the KSME Conference
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    • pp.411-414
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    • 2000
  • Optical Triangulation Probes (OTPs) are widely used for their simple structure. high resolution, and long operating range. However, errors originating from speckle, inclination of the object, source power fluctuation, ambient light, and noise of the detector limit their usability. In this paper, we propose new design criteria for an error-reduced OTP. The light source module for the system consists of an incoherent light source and a multimode optical fiber for eliminating speckle and shaping a Gaussian beam Intensity profile. A diffuse-reflective white copy paper, which is attached to the object, makes the light intensity distribution on the change-coupled device(CCD). Since the peak positions of the intensity distribution are not related to the various error sources, a sub-pixel resolution signal processing algorithm that can detect the peak position makes it possible to construct an error-reduced OTP system

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A Technique to Improve the Readability of Ancient Inscription by Using Optical Triangulation Measurement Principle (광삼각법 측정 원리를 이용한 금석문 가독성 향상 방법)

  • Lee, Geun-Ho;Ko, Sun-Woo;Choi, Won-Ho
    • Journal of Information Technology Services
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    • v.11 no.sup
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    • pp.103-111
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    • 2012
  • In epigraph field to study ancient scripts, alternative readability improvement technologies have been developed to replace existing rubbing method which has low resolution and causes surface pollution of heritages from the viewpoints of extraction process and used materials. Recently many methods which are based on analysis of pixel data for extracting outlines of the specific image have been developed with advancement of image processing techniques. But these methods are not applicable and the results are not satisfied in the damaged inscriptions which are weathered by wind and rain for a long time and in the narrowed one. In this paper laser scanning techniques which uses optical triangulation measurement principle are developed to minimize scanning error. The proposed techniques are consisted of 3 parts:(1) the understanding of optical triangulation measurement principle to find scanning guideline (2) determinations of points interval, scanning distance and scanning angle to guarantee scanning data quality (3) identification of valid point data area which will be used in registration process. The proposed character identification method contributed in decoding an ancient inscription on SeukBingGo in Kyungju.

Modeling and Analysis of Diffuse-type Optical Triangulation Displacement Sensor (난반사형 광삼각법 변위 센서의 모델링 및 거동 해석)

  • 오세백;김경찬;김수현
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.43-46
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    • 2000
  • Optical triangulation displacement sensors(0TDSs) are widely used for their simple struchlre, high resolution, and long operating range. However, there are several factors that must be taken into account in order to obtain high accuracy and reliability Measurement errors from inclinations a? an object surface, prohe signal fluctuations generated by speckle effects. power vanation of a light source, electronic noises, and so on. Previous models of OTDSs can not show reasonable behavior as change of surface inclination and shape of light intensity distribution on the detector. In this paper, we propose a new and reasonable modeling for diffise-type OTDSs based on a geometrical optics. To verify propriety of new modeling, we take basic experiments. Shape of light intensity distribution is asymmetric in both simulation result and experimental result. Both simulation result and experimental result show same tendency of light intensity distribution movement as changing surface inclination

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Coordinate Measuring Technique based on Optical Triangulation using the Two Images (두장의 사진을 이용한 광삼각법 삼차원측정)

  • 양주웅;이호재
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.76-80
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    • 2000
  • This paper describes a coordinate measuring technique based on optical triangulation using the two images. To overcome the defect of structured light system which measures coordinate point by point, light source is replaced by CCD camera. Pixels in CCD camera were considered as virtual light source. The overall geometry including two camera images is modeled. Using this geometry, the formula for calculating 3D coordinate of specified point is derived. In a word, the ray from a virtual light source was reflected on measuring point and the corresponding image point was made on the other image. Through the simulation result, validation of formula is verified. This method enables to acquire multiple points detection by photographing.

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Accuracy Verification of Optical Tracking System for the Maxillary Displacement Estimation by Using of Triangulation (삼각측량기법을 이용한 광학추적장치의 상악골 변위 계측에 대한 정확성 검증)

  • Kyung, Kyu-Young;Kim, Soung-Min;Lee, Jong-Ho;Myoung, Hoon;Kim, Myung-Jin
    • Maxillofacial Plastic and Reconstructive Surgery
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    • v.34 no.1
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    • pp.41-52
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    • 2012
  • Purpose: Triangulation is the process of determining the location of a point by measuring angles to it from known points at either end of a fixed baseline. This point can be fixed as the third point of a triangle with one known side and two known angles. The aim of this study was to find a clinically adaptable method for applying an optical tracking navigation system to orthognathic surgery and to estimate its accuracy of measuring the bone displacement by use of triangulation methods. Methods: In orthognathic surgery, the head position is not fixed as in neurosurgery, so that a head tracker is needed to establish the reference point on the head surface byusing an optical tracking system. However, the operation field is interfered by its bulkiness that makes its clinical use difficult. To solve this problem, we designed a method using an Aquaplast splinting material and a mini-screw in applying a head tracker on a patient's forehead. After that, we estimated the accuracy of measuring displacements of the ball marker by an optical tracking system with a conventional head tracker (Group A) and with a newly designed head tracker (Group B). Measured values of ball markers' displacements by each optical tracking system were compared with values obtained from fusion CT images for an estimation of accuracy. Results: The accuracy of the optical tracking system with a conventional head tracker (Group A) is not suitable for clinical usage. Measured and predictable errors are larger than 10 mm. The optical tracking system with a newly designed head tracker (Group B) shows 1.59 mm, 6.34 mm, and 9.52 mm errorsin threeclinical cases. Conclusion: Most errors were brought on mainly from a lack of reproducibility of the head tracker position. The accuracy of the optical tracking system with a newly designed head tracker can be a useful method in further orthognathic navigation surgery even though the average error is higher than 2.0 mm.

Sensor Structure and Signal Processing System for Precision Optical Displacement Measurement (초정밀 광학식 변위 측정을 위한 센서 구호 밀 신호 처리 시스템)

  • O, Se-Baek;Kim, Gyeong-Chan;Kim, Su-Hyeon;Gwak, Yun-Geun
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.8
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    • pp.40-47
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    • 2001
  • Optical measurement methods make it possible to detect object displacements with high resolution and noncontact measurements. Also, they are very robust against EMI noises and have long operation range. An optical triangulation sensor is one of widely used displacement measurement sensors for its sub-micron resolution, fast response, simple structure, and low cost. However. there are several errors caused by inclinations of a surface. speckle effects, power fluctuations of light sources, and noises of detectors. In this paper, in order to minimize error effects, we performed error analysis and proposed a new structure. Then, we setup a new modeling method and verify it through simulations and experiments. Based on the new model. we propose a new sensor structure and establish design criteria. Finally, we design a signal processing system to overcome a resolution-limited problem of light detectors. The resolution of the proposed system is 0.2${\mu}{\textrm}{m}$ in 5mm operating range.

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The Optical Measurement and Quantitative Analysis of Algesia in Spodoptera litura Larva

  • Chen, Ying-Yun;Chang, Rong-Seng;Tsai, Mi-Yin;Chen, Der-Chin
    • Journal of the Optical Society of Korea
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    • v.19 no.2
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    • pp.169-174
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    • 2015
  • Muscle vibration measurement has long been an unique scientific study, in general, and the direct reaction of animals to feel pain (algesia), either from vascular or muscle contraction, is a complex perceptual experience. Thus this paper proposes a way to measure animal algesia quantitatively, by measuring the changes in muscle vibration due to a pinprick on the surface of the skin of a Spodoptera litura larva. Using the laser optical triangulation measurement principle, along with a CMOS image sensor, linear laser, software analysis, and other tools, we quantify the subtle object point displacement, with a precision of up to $10{\mu}m$, for our chosen Spodoptera litura larva animal model, in which it is not easy to identify the tiny changes in muscle contraction dynamics with the naked eye. We inject different concentrations of formalin reagent (empty needle, 12% formalin, and 37% formalin) to obtain a variety of different muscle vibration frequencies as the experimental results. Because of the high concentrations of reagent applied, we see a high frequency shift of muscle vibration, which can be presented as pain indices, so that the algesia can be quantified.