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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Korean Journal of Optics and Photonics
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Journal DOI :
Optical Society of Korea
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Volume & Issues
Volume 27, Issue 4 - Aug 2016
Volume 27, Issue 3 - Jun 2016
Volume 27, Issue 2 - Apr 2016
Volume 27, Issue 1 - Feb 2016
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Current Status and Prospects of High-Power Fiber Laser Technology (Invited Paper)
Kwon, Youngchul ; Park, Kyoungyoon ; Lee, Dongyeul ; Chang, Hanbyul ; Lee, Seungjong ; Vazquez-Zuniga, Luis Alonso ; Lee, Yong Soo ; Kim, Dong Hwan ; Kim, Hyun Tae ; Jeong, Yoonchan ;
Korean Journal of Optics and Photonics, volume 27, issue 1, 2016, Pages 1~17
DOI : 10.3807/KJOP.2016.27.1.001
Over the past two decades, fiber-based lasers have made remarkable progress, now having reached power levels exceeding kilowatts and drawing a huge amount of attention from academy and industry as a replacement technology for bulk lasers. In this paper we review the significant factors that have led to the progress of fiber lasers, such as gain-fiber regimes based on ytterbium-doped silica, optical pumping schemes through the combination of laser diodes and double-clad fiber geometries, and tandem schemes for minimizing quantum defects. Furthermore, we discuss various power-limitation issues that are expected to incur with respect to the ultimate power scaling of fiber lasers, such as efficiency degradation, thermal hazard, and system-instability growth in fiber lasers, and various relevant methods to alleviate the aforementioned issues. This discussion includes fiber nonlinear effects, fiber damage, and modal-instability issues, which become more significant as the power level is scaled up. In addition, we also review beam-combining techniques, which are currently receiving a lot of attention as an alternative solution to the power-scaling limitation of high-power fiber lasers. In particular, we focus more on the discussion of the schematics of a spectral beam-combining system and their individual requirements. Finally, we discuss prospects for the future development of fiber laser technologies, for them to leap forward from where they are now, and to continue to advance in terms of their power scalability.
Infrared Characteristics of Some Flash Light Sources
Lim, Sang-Yeon ; Park, Seung-Man ;
Korean Journal of Optics and Photonics, volume 27, issue 1, 2016, Pages 18~24
DOI : 10.3807/KJOP.2016.27.1.018
To effectively utilize a flash and predict its effects on an infrared device, it is essential to know the infrared characteristics of the flash source. In this paper, a study of the IR characteristics of flash light sources is carried out. The IR characteristics of three flash sources, of which two are combustive and the other is explosive, are measured with an IR characteristic measurement system over the middle- and long-wavelength infrared ranges. From the measurements, the radiances over the two IR ranges and the radiative temperatures of the flashes are extracted. The IR radiance of flash A is found to be the strongest among the three, followed by those of sources C and B. It is also shown that the IR radiance of flash A is about 10 times stronger than that of flash B, even though these two sources are the same type of flash with the same powder. This means that the IR radiance intensity of a combustive flash source depends only on the amount of powder, not on the characteristics of the powder. From the measured radiance over MWIR and LWIR ranges for each flashes, the radiative temperatures of the flashes are extracted by fitting the measured data to blackbody radiance. The best-fit radiative temperatures (equivalent to black-body temperatures) of the three flash sources A, B, and C are 3300, 1120, and 1640 K respectively. From the radiance measurements and radiative temperatures of the three flash sources, it is shown that a combustive source radiates more IR energy than an explosive one; this mean, in turn, that the effects of a combustive flash on an IR device are more profound than those of an explosive flash source. The measured IR radiances and radiative temperatures of the flash sources in this study can be used to estimate the effects of flashes on various IR devices, and play a critical role for the modeling and simulation of the effects of a flash source on various IR devices.
Designing the Optical Structure of a Multiscale Gigapixel Camera
Moon, Hee jun ; Rim, Cheon-Seog ;
Korean Journal of Optics and Photonics, volume 27, issue 1, 2016, Pages 25~31
DOI : 10.3807/KJOP.2016.27.1.025
We derive 28 optical structural equations based on our two previous theoretical and experimental papers about a gigapixel camera, which were published in 2013 and 2015 respectively. Utilizing these 28 equations, we are able to obtain an integrated understanding of optical structure for a multiscale gigapixel camera system, in addition to obtaining numerical values for structural parameters very directly and easily.
Optical Design of a Laser Scanning System Stable Against Wavelength and Temperature Variations
Kim, Da Ae ; Lee, Jong-Ung ;
Korean Journal of Optics and Photonics, volume 27, issue 1, 2016, Pages 32~40
DOI : 10.3807/KJOP.2016.27.1.032
The characteristics of an optical system vary depending on wavelength and ambient temperature. Based on the thin-lens approximation, we investigate the conditions for stabilizing an optical system against wavelength and temperature variations at the same time. The conditions are applied to designing a laser scanning system consisting of two lenses. The change in the effective focal length of the scanning system against wavelength and temperature variations is very small, as expected.
Three-Dimensional Shape Measurement of a Specular Object by LED Array Reflection
Kim, Jee Hong ;
Korean Journal of Optics and Photonics, volume 27, issue 1, 2016, Pages 41~46
DOI : 10.3807/KJOP.2016.27.1.041
An optical method to measure the three-dimensional (3D) shape of a surface with specular reflection is proposed. The proposed method is based on the analysis of the geometric path of the light from a point source, and the relative displacements of points in the reflection image. The 3D shape of a concave mirror is shown to be determined approximately via experiments, where the vision system consists of LED array illumination, a half-mirror, and an imaging sensor.