• Journal of Institute of Control, Robotics and Systems
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• v.18 no.5
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• pp.479-486
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• 2012

In this paper, a ranging system is proposed that is able to measure 360 degree omnidirectional distances to environment objects. The ranging system is based on the structured light imaging system with catadioptric omnidirectional mirror. In order to make the ranging system robust against environmental illumination, efficient structured light image processing algorithms are developed; sequential integration of difference images with modulated structured light and radial search based on Bresenham line drawing algorithm. A dedicated FPGA image processor is developed to speed up the overall image processing. Also the distance equation is derived in the omnidirectional imaging system with a hyperbolic mirror. It is expected that the omnidirectional ranging system is useful for mapping and localization of mobile robot. Experiments are carried out to verify the performance of the proposed ranging system.

• Journal of Astronomy and Space Sciences
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• v.30 no.4
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• pp.269-277
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• 2013

In this study, we present results of precise orbital geodetic parameter estimation using satellite laser ranging (SLR) observations for the International Laser Ranging Service (ILRS) associate analysis center (AAC). Using normal point observations of LAGEOS-1, LAGEOS-2, ETALON-1, and ETALON-2 in SLR consolidated laser ranging data format, the NASA/GSFC GEODYN II and SOLVE software programs were utilized for precise orbit determination (POD) and finding solutions of a terrestrial reference frame (TRF) and Earth orientation parameters (EOPs). For POD, a weekly-based orbit determination strategy was employed to process SLR observations taken from 20 weeks in 2013. For solutions of TRF and EOPs, loosely constrained scheme was used to integrate POD results of four geodetic SLR satellites. The coordinates of 11 ILRS core sites were determined and daily polar motion and polar motion rates were estimated. The root mean square (RMS) value of post-fit residuals was used for orbit quality assessment, and both the stability of TRF and the precision of EOPs by external comparison were analyzed for verification of our solutions. Results of post-fit residuals show that the RMS of the orbits of LAGEOS-1 and LAGEOS-2 are 1.20 and 1.12 cm, and those of ETALON-1 and ETALON-2 are 1.02 and 1.11 cm, respectively. The stability analysis of TRF shows that the mean value of 3D stability of the coordinates of 11 ILRS core sites is 7.0 mm. An external comparison, with respect to International Earth rotation and Reference systems Service (IERS) 08 C04 results, shows that standard deviations of polar motion $X_P$ and $Y_P$ are 0.754 milliarcseconds (mas) and 0.576 mas, respectively. Our results of precise orbital and geodetic parameter estimation are reasonable and help advance research at ILRS AAC.

• Journal of Space Technology and Applications
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• v.4 no.1
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• pp.1-11
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• 2024

Korea Astronomy and Space Science Institute (KASI) developed an satellite laser ranging (SLR) system for tracking space objects using ultra-pulsed lasers. For the safe operation of SLR system, aircraft surveillance radar system (ASRS) was developed to prevent human damage from high power laser transmitted from the SLR system. The ASRS consists of the radar hardware subsystem (RHS) and main control subsystem (MCS), in order to detect flying objects in the direction of laser propagation and then stop immediately the laser transmission. The RHS transmits the radio frequency (RF) pulse signals and receives the returned signals, while the MCS analyzes the characteristics of received signals and distinguishes the existence of flying objects. If the flying objects are determined to be existed, the MCS sends the command signal to the laser controller in SLR system to pause the laser firing. In this study, we address the interface and operational scenarios of ASRS, including the design of RHS and MCS. It was demonstrated in the aircraft experiments that the ASRS could detect an aircraft and then stop transmitting high power laser successfully.

• Proceedings of the Korean Society of Laser Processing Conference
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• 1998.11a
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• pp.0-0
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• 1998

-Part I- As market needs become more various, the production of smaller quantities of a wider variety of products becomes increasingly important. In addition, in order to meet demands for more efficient production, long-term unmanned factory operation is prevailing at a remarkable pace. Within this context, laser machines are gaining increasing popularity for use in applications such as cutting and welding metallic and ceramic materials. FANUC supplies four models of $CO_2$ laser oscillators with laser power ranging from 1.5㎾ to 6㎾ on an OEM basis to machine tool builders. However, FANUC has been requested to produce laser oscillators that allow more compact and lower-cost laser machines to be built. To meet such demands, FANUC has developed six models of Slab type YAG laser oscillators with output power ranging from 150W to 2㎾. These oscillators are designed mainly fur cutting and welding sheet metals. The oscillator has an exceptionally superior laser beam quality compared to conventional YAG laser oscillators, thus providing significantly improved machining capability. In addition, the laser beam of the oscillator can be efficiently transmitted through quartz optical fibers, enabling laser machines to be simplified and made more compact. This paper introduces the features of FANUC’s developed Slab type YAG laser oscillators and their applications. - Part II - All-solid-state lasers employing laser diodes (LD) as a source of pumping solid-state laser feature high efficiency, compactness, and high reliability. Thus, they are expected to provide a new generation of processing tools in various fields, especially in automobile and aircraft industries where great hopes are being placed on laser welding technology for steel plates and aluminum materials for which a significant growth in demand is expected. Also, in power plants, it is hoped that reliability and safety will be improved by using the laser welding technology. As in the above, the advent of high-power all-solid-state lasers may not only bring a great technological innovation to existing industry, but also create new industry. This is the background for this project, which has set its sights on the development of high-power, all-solid-state lasers with an average output of over 10㎾, an oscillation efficiency of over 20%, and a laser head volume of below 0.05㎥. FANUC Ltd. is responsible for the research and development of slab type lasers, and TOSHIBA Corp. far rod type lasers. By pumping slab type Nd: YAG crystal and by using quasi-continuous wave (QCW) type LD stacks, FANUC has already obtained an average output power of 1.7㎾, an optical conversion efficiency of 42%, and an electro-optical conversion efficiency of 16%. These conversion efficiencies are the best results the world has ever seen in the field of high-power all-solid-state lasers. TOSHIBA Corp. has also obtained an output power of 1.2㎾, an optical conversion efficiency of 30％, and an electro-optical conversion efficiency of 12%, by pumping the rod type Nd: YAG crystal by continuous wave (CW) type LD stacks. The laser power achieved by TOSHIBA Corp. is also a new world record in the field of rod type all-solid-state lasers. This report provides details of the above results and some information on future development plans.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.68-68
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• 2000

In this paper a very brief review of historical development of optical science and technology in China is presented. More attention has been pain on Modem Optics, which developed since 1950s. The recent development of optical science and technology in following fields are introduced. 1. Optical engineering and instrumentation (tracking theodolites, high speed cameras, satellite laser ranging systems, satellite flying attitude control, cameras for remote sensing, astronomical optical instrument) 2. Applied optics (adaptive optics, optical metrology, infrared optics, optical processing, optical holography) 3. Laser science and technology (ultrashort pulse lasers, UV-X ray lasers, high power laser facilities and laser fusion, laser isotope separation) 4. Laser and nonlinear materials (rare earth elements doped laser glasses and crystals, tunable laser crystals, borate series and organic nonlinear crystals) 5. Optoelectronic science and technology (Optical communication, optical data storage, optical computing) The current situation and developing prospect of optical and optoelectronic industry in China are presented. Furthermore it points out that the optical industry could be developed vigorously only if products development capacity is enhanced and new products industrialization is heightened. The main research and education institutions in the optics field in China, as well as the Chinese Optical Society (COS) are introduced.

• Journal of Space Technology and Applications
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• v.4 no.1
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• pp.48-61
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• 2024

In this paper, we introduce the concept of the cube satellite Chungnam National University Laser Unity Bus (CLUB), which can provide an integrated infrastructure for various ground-space laser applications. With the advent of the new space era, the rapid expansion of space utilization has begun to reveal the limitations of conventional radio frequencies. As space missions diversify, lasers are garnering attention as a viable alternative. Between ground and space, lasers are applied in various fields including satellite laser ranging (SLR), laser weapons, and laser communication. However, laser used between the ground and space are significantly influenced by the Earth's atmosphere. Consequently, understanding the atmospheric effects on laser propagation is crucial. In particular, atmospheric turbulence, which refracts and distorts laser beams, intensifies closer to the Earth's surface, exerting a greater impact on the uplink than on the downlink. While downlink verification is facilitated by ground detection, verifying the uplink poses challenges due to the necessity of space-based detection. In response to these challenges, we propose the idea of cube satellite as a means to enhance understanding and verification of laser propagation in the uplink. Additionally, we present the results of conceptual design by analyzing requirements, focusing on mission design of the CLUB cube satellite, following the stages of systems engineering for systematic cube satellite development.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.4
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• pp.644-650
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• 2012

This paper show the 2kW fiber laser cutting properties of SS400. The study was comparison of traditional 4kW $CO_2$ Laser cutting and 2kW Fiber laser cutting characteristics for the application of Industrial 2D Laser Cutting Machine. The laser used in this investigation was an IPG YLU-2000 multi-mode Ytterbium Fiber machine with a maximum power of 2000W and a wave length of 1070 nm. The laser was used in its Continuous Wave (CW) mode with an approximately top hat beam intensity distribution. Fiber laser high quality cuts at a large range of speeds (ranging from 2000 to 3800 mm/min) which has been obtained for the 2.3mm Sheet of SS400. 2kW power Fiber laser cut was able to max. 20mm sheets of SS400 (speed range from 650 to 850 mm/min). Fiber laser cutting used in conventional hole nozzle could cut 12mm SS400 but used in special dual cutting nozzle could cut 20mm SS400.

• Korean Journal of Optics and Photonics
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• v.27 no.4
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• pp.133-142
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• 2016

This paper presents the design and simulation of a three-dimensional pixel-by-pixel scanning light detection and ranging (LIDAR) system with a microelectromechanical system (MEMS) scanning mirror and direct sequence optical code division multiple access (DS-OCDMA) techniques. It measures a frame with $848{\times}480$ pixels at a refresh rate of 60 fps. The emitted laser pulse waves of each pixel are coded with DS-OCDMA techniques. The coded laser pulse waves include the pixel's position in the frame, and a checksum. The LIDAR emits the coded laser pulse waves periodically, without idle listening time to receive returning light at the receiver. The MEMS scanning mirror is used to deflect and steer the coded laser pulse waves to a specific target point. When all the pixels in a frame have been processed, the travel time is used by the pixel-by-pixel scanning LIDAR to generate point cloud data as the measured result.

• Laser Solutions
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• v.13 no.2
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• pp.6-9
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• 2010

In printed electronics, printing rolls are used to transfer electronic ink onto a flexible substrate. Generally printing rolls are being made by the indirect laser method which is based on the etch process, thus not environment-friendly and not suitable for making a large printing roll. For the pursuit of making a large printing roll for mass printing of electronic devices, we have directly engraved micro-patterns into a Zn plated printing roll using a 30W pulse-modulated fiber laser. We have successfully engraved line patterns ranging from about 15-30${\mu}m$ in width.

• Laser Solutions
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• v.11 no.4
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• pp.1-6
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• 2008

This paper describes microscale laser structuring of electrospun(ES) PCL and PET nanofiber meshes. Electrospinning produces non-woven meshes of synthetic or natural materials fibers with diameters ranging from micron down to the nanometer scales that are advantageous for the supporting the growth of the small scale structures. Ultrashort laser found to be effective on the fabrication of engineeredtissue scaffold with minimum heat affect and ultra precision ablation patterns. The affect of energy range for ablation quality was analyzed and ablation characteristics of PCL and PET were compared.