• Proceedings of the KSME Conference
• /
• 2005.11a
• /
• pp.213.1-213.1
• /
• 2005

• Korean Journal of Optics and Photonics
• /
• v.19 no.2
• /
• pp.132-139
• /
• 2008

In scanning laser optical tweezers, high speed scanning stages are used to manipulate a laser beam spot. Due to the inertia of the stage, the output scanning signal decreases with increased frequency of the input signal. This discrepancy in the signals is difficult to observe since most of the energy from the laser beam is blocked out to avoid CCD damage. In this paper, we propose two methods to alleviate these problems. Firstly, frequency responses of piezo stages are measured to analyze the signal drops and the input signal is compensated accordingly. Secondly, an overlay of the scanning path is drawn on the live monitoring screen to enhance the visibility of the scanning path. The result is a drop-compensated scanning with clear path view.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.05a
• /
• pp.308-308
• /
• 2004

쾌속조형기술은 설계형상의 확인, 시작품의 제작, 금속 및 세라믹 부품에의 응용, 동시공학, 의료, 마이크로 머신 둥 제조업 전반에 걸쳐서 많은 응용이 이루어지고 있다 여러 가지의 기술들이 개발되고 이를 응용한 장비들이 생산되어 보급됨으로써 이러한 적용분야들은 점차 확대되고 있다. 본 연구에서는 분말을 소결, 적층하여 원하는 형상을 만들어내는 SLS(Selective Laser Sintering) 장비를 개발하는데 있어서 레이저 경로의 제어를 통한 분말을 소결시키는 부분인 레이저 주사 시스템(laser scanning system)을 개발하고자 한다.(중략)

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.1295-1298
• /
• 2004

Selective Laser Sintering(SLS) method is one of Rapid Prototyping(RP) technologies. It is used to fabricate desirable part to sinter powder and stack the fabricated layer. To develop this SLS machine, it needs effective scanning path and the development of scanning device. This paper shows how to make fast scanning path with respect to scan spacing, laser beam size and scanning direction from 2-dimensional sliced file generated in commercial CAD/CAM software. Also, we develop the scanning device and its control algorithm to precisely follow the generated scanning path. Scanning path affects precision and total machining time of the final fabricated part. Sintering occurs using infrared laser which has high thermal energy. As a result, shrinkage and curling of the fabricated part occurs according to thermal distribution. Therefore, fast scanning path generation is needed to eliminate the factors of quality deterioration. It highly affects machining efficiency and prevents shrinkage and curling by relatively lessening the thermal distribution of the surface of sintering layer. To generate this fast scanning path, adaptive path generation is needed with respect to the shape of each layer, and not simply x, y scanning, but the scanning of arbitrary direction must be enabled. This paper addresses path generation method to focus on fast scanning, and development of scanning system and control algorithm to precisely follow generated path.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.47 no.6
• /
• pp.91-96
• /
• 2010

A laser speckle is a random pattern that has a granular appearance produced by reflected light when a coherent laser illuminates an irregular course surface. Laser speckle system has many advantages. It can detect some animals functional parts. Moreover, it relatively consists of simple and in-expensive system. It is very important that detecting micro-vessels through image processed image. Current study is to improve image quality through variable image processing method. But this paper made laser speckle endoscope for miniaturization and commercialization laser speckle system. We had endoscope test through goldfish's tail. We will compare the processed speckle image and halogen image.

• Journal of the Korean Society for Precision Engineering
• /
• v.26 no.8
• /
• pp.29-34
• /
• 2009

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.04a
• /
• pp.405-409
• /
• 1997

Voronoi diagrams are applied in varios field such as NC toolpath generation, VLSI design and robot path planning because of their geometric charcteristics. In this paper, Voronoi diagrams are introduced on polygon constructed by line segments only and with constant offset. Bisector curves for two arbitrary objects, which is the combination of line segment and arc, are defined as parametric fuction where the parameter is used as offset. Offset curves are applied on the generation of laser scanning path for the stereolithography and shows a good result from several examples.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.10a
• /
• pp.1037-1040
• /
• 2002

In micro-stereolithography technology, fabrication conditions that include laser power, laser scan speed, laser scan pitch, and material property of photopolymer such as penetration depth and critical exposure are considered as major process variables. But the existing scan path generation methods based only on CAD model have not taken them into account, which has resulted in cross-section dimension of low accuracy. Thus, to enhance cross-section dimensional accuracy, the physical resin solidification n phenomena should be reflected in laser scan path generation and stage operating code. In this paper, multi-line experiments based on single line solidification model are performed. And the method for improving cross-section dimensional accuracy is presented, which is to apply the database based on experimental results to laser scan path generation.

• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.1389-1393
• /
• 2007

Selective Laser Sintering (SLS) is currently recognized as a leading process in the new field of solid freeform fabrication (SFF). It is used to fabricate in a short time any 3 dimensional shapes by layer-by-layer sintering of polymer, ceramic or metal powder. To develop this SFF system, it needs effective laser scanning path, temperature and z-axis control for lamination. Therefore, in this study, through the application of control algorithm for sintering process have performed, temperature evaluation for sintering process has performed and the manufacturing sample using SLS process.

• Spatial Information Research
• /
• v.7 no.1
• /
• pp.63-79
• /
• 1999

In this research, the operational principle and the internal algorithm of theodolite measuring systems are studied and coded for a new software, and the feasibility of the laser system for the above mentioned usage is studied by simulation set-up of the system in the laboratory environment, and for the theodolite system modules for the communication between theodolite and computer is implemented, the data collection and storage, the simultaneous photogrammetric ' bundle ' adjustment for the theodolite position and the target points are coded, compiled and tested. for the simulation set-up of the laser system extensive studies on laser sources and laser detectors are performed, the system composition for the system simulation in the laboratory environment is studied and implemented, and the beam fluctuation due to the environmental changes in the course of the laser beam, such as changes in current of wind or in temperature is experimented. According to Experiment on the Source of 17 meters interval and the Detector, Laser beam is almost doesn't depend on air How, but it is effected by variations of temperature and light. Selecting cloudy day and time without change of temperature, it was realized that it is possible to perform deformation measurement more than approximately 2mm precision.precision.