• Journal of Astronomy and Space Sciences
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• v.30 no.4
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• pp.307-314
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• 2013

Infrared optical systems are operated at low temperature and vacuum (LT-V) condition, whereas the assembly and alignment are performed at room temperature and non-vacuum (RT-NV) condition. The differences in temperature and pressure between assembly/alignment environments and operation environment change the physical characteristics of optical and opto-mechanical parts (e.g., thickness, height, length, curvature, and refractive index), and the resultant optical performance changes accordingly. In this study, using input relay optics (IO), among the components of the Immersion GRating INfrared Spectrograph (IGRINS) which is an infrared spectrograph, a simulation based on the physical information of this optical system and an actual experiment were performed; and optical performances in the RT-NV, RT-V, and LT-V environments were predicted with an accuracy of $0.014{\pm}0.007{\lambda}$ rms WFE, by developing an adaptive fitting line. The developed adaptive fitting line can quantitatively control assembly and alignment processes below ${\lambda}/70$ rms WFE. Therefore, it is expected that the subsequent processes of assembly, alignment, and performance analysis could not be repeated.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.598-603
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• 2019

Three-dimensional shape measurement technology is used in various industries. Among them, optical three-dimensional shape measurement techniques based on the optical trigonometry are mainly used in the field of semiconductor product inspection, where large quantities of three-dimensional shape measurements are made daily in factories and fine measurements are also required. The light source and the drive circuit, which are components of three-dimensional measurement equipment based on this optical trigonometry, produce heat generated by prolonged operation, and may be exposed to conditions where the ambient temperature is not constant, resulting in temperature-induced measurement errors. In this study, the compensation method of the Thermal Errors for Phase Measuring Profilometry is proposed. Three-Dimensional Shape Measurement Equipment based on Phase Measuring Profilometry is implemented to measure the height of an object and ambient temperature for 10 Hours, and a regression line was obtained line by making simple linear regression using measured temperature and height values. This regression line was used to correct the error of the height measurement according to the temperature, and thermal error was from 139.88 um(Micrometer) to 13.12 um.

• Journal of Internet Computing and Services
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• v.16 no.1
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• pp.29-37
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• 2015

In this paper, we propose a robust pre-processing module for camera-based Optical Music Score Recognition (OMR) on mobile device. The captured images likely suffer for recognition from many distortions such as illumination, blur, low resolution, etc. Especially, the complex background music sheets recognition are difficult. Through any symbol recognition system, the staff line height and staff line space are used many times and have a big impact on recognition module. A robust and accurate staff line height and staff line space are essential. Some staff line height and staff line space are proposed for binary image. But in case of complex background music sheet image, the binarization results from common binarization algorithm are not satisfactory. It can cause incorrect staff line height and staff line space estimation. We propose a robust staff line height and staff line space estimation by using run-length encoding technique on edge image. Proposed method is composed of two steps, first step, we conducted the staff line height and staff line space estimation based on edge image using by Sobel operator on image blocks. Each column of edge image is encoded by run-length encoding algorithm Second step, we detect the staff line using by Stable Path algorithm and removal the staff line using by adaptive Line Track Height algorithm which is to track the staff lines positions. The result has shown that robust and accurate estimation is possible even in complex background cases.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.519-523
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• 2009

This paper presents the analysis of pitch static attitude (PSA) in thermally assisted magnetic recording (TAMR) suspension. The TAMR suspension using an optical fiber has high stiffness such as vertical, pitch and roll. Therefore, P-torque is greatly increased by the optical fiber. Also, flying height (FH) of the slider with TAMR suspension can be largely changed by PSA. In this paper, we focus on the FH by PSA of TAMR suspension. The FH is investigated using various PSA and proper PSA is proposed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.391-394
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• 2003

Laser direct writing process is developed 3rd harmonic Diode Pumped Solid State Laser with the near visible wavelength of 355 m sensitive polymer is irradiated by UV laser and developed using polymer solvent to obtain quasi-3D. It is important to reduce line width for image mode waveguides, so some investigations will be carried out in various conditions of process parameters such as laser power, writing speed, laser focus and optical properties of polymer. This process could be to fabricate a single mode waveguide without expensive mask projection method. Experimentally, the patterns of trapezoidal shape were manufactured into dimension of 8.4 mm width and 7.5 mm height. Propagation loss of straight waveguide measured 3 dB/cm at 1,550 nm.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.6
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• pp.1178-1182
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• 2011

The best methods for distribution controled of LED lighting fixtures is control to designed LED chip array, lens and reflector. However, lens design need distribution design to reflector for low-wattage LED lighting because of difficulty of production and reduction of light efficiency. In addition, it needs maximize of thermal performance to improve the efficiency and reliability of device. As a result, for the height of reflector 40[mm] and Inclination 25[$^{\circ}$], we can see the best distribution properties, and, in the thermal properties, junction temperature MCPCB 62.9 [$^{\circ}C$], FR4 PCB 89.6 [$^{\circ}C$], FR4 PCB from Via-hole is 63.1 [$^{\circ}C$]. it may improve for thermal properties for makes the Via-hole.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.61 no.2
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• pp.93-96
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• 2012

We have designed high performance prism light-guide plate (LGP) in 17 inch TFT-LCD. In test result to embody high brightness BLU in case of LGP of base and upper surface with 17 inch, thickness 8mm adding prism construct. Using optical simulation, we forecast the brightness and uniformity in LGP with prism structure. And we adopted novel injection mold method and Nickel stamper to make actual evolution sample. Novel injection mold process has steady heating time zone in heat cycle time of injection mold process. For this novel heat cycle control, we achieved above 90[%] height prism structure as our design. It is superior brightness improvement than previous that of printing form about some 20[%] and in this course to embody actual material it succeeded prism LGP production by 17 inch injection form process.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.234-237
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• 2002

To detect external vibration signals on the latticed fence structure, distributed fiber optic sensor using Sagnac interferometer was fabricated and tested. The latticed structure fabricated with dimension of 170cm in width and 180cm in height, the optical fiber, 50m in length, distributed and fixed on the latticed structure. It was verified the sensitivity of the Sagnac interferometer using the PZT phase modulator. Fiber optic external vibration signal spplied to the latticed fence structure from 100Hz to several kHz. The interferometeric fiber optic sensor detected the excited vibration signal very effectively without any signal processing. The detected optical signals were compared and analyzed to the detected acclerometer signals.

• Journal of the Optical Society of Korea
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• v.19 no.1
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• pp.80-83
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• 2015

White reflective patterns are very difficult to fabricate, due to the scattering and reflection of light, especially when the pattern size goes down to micron size. A reflective white barrier structure of height $50{\mu}m$ and width $80{\mu}m$ was fabricated using dry-film resist as an intermediate reverse pattern. The reverse dry-film resist pattern was coated with an $SiO_2$ layer by sputtering, to protect the resist from chemical attack by the radical molecules in UV white resin. The UV white resin was applied on the dry-film resist pattern and then cured with ultraviolet light. The fine three-dimensional reflective patterns were finished by removing the dry-film resist.

• Journal of the Optical Society of Korea
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• v.15 no.4
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• pp.352-356
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• 2011

Dual-wavelength holography has a better axial range than single-wavelength holography, allowing unambiguous phase imaging. Partial coherence sources reduce coherent noise, resulting in improved reconstructed images. We measured a ball-grid array using dual-wavelength holography with partial coherence sources. This holography method is useful for measurement samples that exhibit coherence noise and have a step height larger than the single wavelength used in holography.