• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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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.

• 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.

• 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.

• Proceedings of the Optical Society of Korea Conference
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• 1997.08a
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• pp.81-81
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• 1997

• Current Optics and Photonics
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• v.5 no.3
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• pp.298-305
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• 2021

Modern distance sensing methods employ various measurement principles, including triangulation, time-of-flight, confocal, interferometric and frequency comb. Among them, the triangulation method, with a laser light source and an image sensor, is widely used in low-cost applications. We developed an omnidirectional two-dimensional (2D) distance sensor based on the triangulation principle for indoor floor mapping applications. The sensor has a range of 150-1500 mm with a relative resolution better than 4% over the range and 1% at 1 meter distance. It rotationally scans a compact one-dimensional (1D) distance sensor, composed of a near infrared (NIR) laser diode, a folding mirror, an imaging lens, and an image detector. We designed the sensor layout and configuration to satisfy the required measurement range and resolution, selecting easily available components in a special effort to reduce cost. We built a prototype and tested it with seven representative indoor wall specimens (white wallpaper, gray wallpaper, black wallpaper, furniture wood, black leather, brown leather, and white plastic) in a typical indoor illuminated condition, 200 lux, on a floor under ceiling mounted fluorescent lamps. We confirmed the proposed sensor provided reliable distance reading of all the specimens over the required measurement range (150-1500 mm) with a measurement resolution of 4% overall and 1% at 1 meter, regardless of illumination conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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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.

• 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.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.7
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• pp.40-50
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• 1999

Recently, a laser displacement sensor is widely used for the manufacturing automation. The sensor is generally composed of a diode laser and a light receiving device. The diode laser emits a laser beam and the receiving device detects the light reflected from the measured object. The object position is obtained based upon triangulation method. As a light receiving device, a PSD is usually utilized since its structure is very simple and rugged and has a high accuracy. Although the theoretical relationship for this sensor had been developed, the characteristics of the sensor have not been much experimentally studied. In this paper, several experimental results will presented. The measurement accuracy is affected by the surface conditions such as the reflectance characteristics, the angle of the object's surface and the laser intensity. In addition, it is found that the PSD and the signal processing circuit have nonlinearities and showed that those nonlinearities can be reduced by controlling the emitting laser intensity.

• Journal of the Ergonomics Society of Korea
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• v.20 no.3
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• pp.77-88
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• 2001

A three dimensional body scanner for anthropomentric measurement has been developed. In this study, the slit laser beam projection method followed by digital image processing was used to provide accurate spatial data with the typical optical triangulation method to overcome the many difficulties in traditional in accurate and time-consuming tactic measurement method using rulers and gauges. Compared with other commercialized scanners. this system can obtain a relatively wide range of data at a much lower cost by the specially designed scanning process such as the simultaneous acquisition of vertical and horizontal body cross-section profiles.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.10
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• pp.1730-1741
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• 1997

In this paper, we developed a surface profile measuring system and a profile measuring software for EGL conductor roll. For the profilemeter, we designed a linear guided control system with Laser displacement sensors and developed a 3-dimensional software. Additionally, the AC motor and AC motor driver were used to control the precise position of linear guide system. The measuring principle of the Laser sensor is optical triangulation method. Also, two Laser sensors were used to remove the disturbance and vibration effects of the linear guide system.