• Journal of the Korean Society for Precision Engineering
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• v.32 no.11
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• pp.983-988
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• 2015

This paper details a new ultra-precise turning method for increasing surface quality, "Multi Point B Axis Control Method." Machined surface error is minimized by the compensation machining process, but the process leaves residual chip marks and surface roughness. This phenomenon is unavoidable in the diamond turning process using existing machining methods. However, Multi Point B axis control uses a small angle (< $1^{\circ}$) for the unused diamond edge for generation of ultra-fine surfaces; no machining chipping occurs. It is achieved by compensated surface profiling via alignment of the tool radial center on the center of the B axis rotation table. Experimental results show that a diamond turned surface using the Multi Point B axis control method achieved P-V $0.1{\mu}m$ and Ra 1.1nm and these ultra-fine surface qualities are reproducible.

• Korean Journal of Optics and Photonics
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• v.17 no.4
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• pp.354-358
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• 2006

A silicon lens and an insulator of pyrex, components of a micro-electron column, should be assembled by aligning and stacking simultaneously. An optical alignment of a diffraction beam and a laser welding were employed for the assembly of a source lens and an Einzel lens with precision within $\pm$4% for the maximum aperture size. The experimental condition for optical alignment and laser welding are explained. Anodic bonding was used to assist in stacking lenses. A micro-electron column of smaller apertures assembled with precise alignment and fabrication was tested with a current image of a Cu grid of 9$\mu$m in linewidth, and showed a higher resolution in acceleration mode.

• Journal of the Optical Society of Korea
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• v.19 no.6
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• pp.604-613
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• 2015

An unobstructed off-axis two-mirror system is presented in this paper. First a suitable initial configuration is established based on third-order aberration theory. In order to achieve a wide field of view (FOV) with high image quality , the diffractive mirror is adopted in the two-mirror system to increase the optimization freedom and the aberration relationship between diffractive phase coefficients and Zernike coefficients is derived. Furthermore, a complete comparison design example with a focal length of 1200 mm, F-number of 12, and FOV of 40° × 2° is given to verify the aberration correction ability of the diffractive mirror. The system average wavefront error is 0.007 λ (λ=0.6328 μm) developed from 0.061 λ when the system didn’t adopt the diffractive mirror. In this system the phase modulation function of the diffractive mirror is established as an even function of x, so we could obtain a symmetrical imaging quality about the tangential plane, and the symmetric aberration performance also brings considerable convenience to alignment and testing for the system.

• Korean Journal of Materials Research
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• v.14 no.3
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• pp.186-190
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• 2004

An electron beam microcolumn composed of an electron emitter, micro lenses, scan deflector, and focus lenses have been fabricated and tested in the STEM mode. In this paper, we report a technique of precisely aligning the electron lenses by the laser diffraction patterns instead of the conventional alignment method based on aligner and STM. STEM images of a standard Cu-grid were observed using a fabricated microcolumn under both the retarding and accelerating modes.

• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.424-430
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• 2011

A novel T-type polyurethane 7 containing 1-(2,5-dioxyphenyl)-2-(5-(1,2,2-tricyanovinyl)-2-thienyl)ethenes as NLO chromophores, which constitute part of the polymer backbone, was prepared. Polyurethane 7 is soluble in common organic solvents such as DMF and DMSO. It shows a thermal stability up to $270^{\circ}C$ from TGA thermogram with $T_g$ value obtained from DSC thermogram near $155^{\circ}C$. The second harmonic generation (SHG) coefficient ($d_{33}$) of poled polymer film at 1560 nm fundamental wavelength is $3.56{\times}10^{-9}$ esu. Polymer 7 exhibits a thermal stability even at $5^{\circ}C$ higher than $T_g$, and no significant SHG decay is observed below $160^{\circ}C$, which is acceptable for nonlinear optical device applications.

• Korean Journal of Optics and Photonics
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• v.15 no.6
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• pp.527-530
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• 2004

Using a polarimetry based on the rotating analyzer ellipsometer, a technique of measuring off-alignment angle between the slow-axis of the LCD (Liquid Crystal Display) polarizing plate and the transmission axis of the compensating plate attached to the polarizing plate is proposed. It is anticipated that this technique will reduce the optic axis off-alignment error coming from the process of attaching the compensating plate to the LCD polarizing plate markedly, and therefore will help maintain the quality of LCD display image uniformly.

• Journal of the Optical Society of Korea
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• v.19 no.5
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• pp.477-486
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• 2015

We propose a novel calibration method which can be applied to all kinds of panel-type multi-view displays. We analyze how the angular, the axial, and the lateral misalignment affects the 3D image quality in a panel-type multi-view display. We demonstrate the ray optics simulation with a 3-view slanted parallax barrier system using pentile display for the quantitative calculation. Based on the analysis, we propose a new alignment pattern for all kinds of panel-type multi-view displays. The proposed pattern is sensitive to all of the angular, the axial, and the lateral misalignments. The high spatial frequency images and on and off alignment in the proposed pattern help observers to calibrate the system easily. We theoretically show the generality of the proposed alignment pattern and verify the pattern with image simulations and experiments.

• Bulletin of the Korean Chemical Society
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• v.29 no.5
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• pp.933-938
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• 2008

2,4-Di-(2'-hydroxyethoxy)benzylidenemalononitrile (3) was prepared and polymerized with terephthaloyl chloride and adipoyl chloride to yield novel Y-type polyesters 4 and 5 containing dioxybenzylidenemalononitrile groups as NLO-chromophores, which constituted parts of the polymer backbone. The resulting polymers 4 and 5 are soluble in common organic solvents such as acetone and N,N-dimethylformamide. Polymers 4 and 5 showed thermal stability up to 300 ${^{\circ}C}$ in thermogravimetric analysis with glass-transition temperatures obtained from differential scanning calorimetry in the range 83-94 ${^{\circ}C}$. The second harmonic generation (SHG) coefficients ($d_{33}$) of poled polymer films at the 1064 nm fundamental wavelength were around $6.48\;{\times}\;10^{-9}$ esu. The dipole alignment exhibited high thermal stability even at 10 ${^{\circ}C}$ higher than $T_g$ and no significant SHG decay was observed below 105 ${^{\circ}C}$ partially due to the main-chain character of polymer structure, which is acceptable for NLO device applications.

• Transactions of the Society of Information Storage Systems
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• v.7 no.2
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• pp.53-59
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• 2011

We have developed a compact and high-power mode-locked fiber laser for multilayered optical memory. Fiber lasers have the potential to be compact and stable light sources that can replace bulk solid-state lasers. To generate high-power pulses, we used stretched-pulse mode locking. The average power and pulse width of the output pulse from the fiber laser that we developed were 109 mW and 2.1 ps, respectively. The dispersion of the output pulse was compensated with an external single-mode fiber of 2.5 m length. The pulse was compressed from 2.1 ps to 93 fs by dispersion compensation. The fiber laser we have developed is possible to use as a light source of multilayered optical memory. We also present a fiber confocal microscope as an alignment-free readout system of multilayered optical memories. The fiber confocal microscope does not require fine pinhole position alignment because the fiber core is used as the point light source and the pinhole, and both of which are always located at the conjugated point. The configuration reduces the required accuracy of pinhole position alignment. With these techniques we can present an all-fiber recording and readout system for multilayered memories.

• Korean Journal of Optics and Photonics
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• v.16 no.5
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• pp.440-445
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• 2005

The limitation of measurement accuracy and reliability of autostigmatic null lens system are studied for the cases of using inter-distance of null lenses as the adjustment factor of alignment and fixing the distance by mounting. If we investigate the first case, the wavefront aberration of null lens system is compensated by the adjustment process even though the shape of aspherical surface is not properly fabricated. As the result, it brings about the problem of measurement reliability. However, for the fixing process by mounting null lenses, it doesn't cause the reliability problem because the wavefront aberration of null lens system is not compensated. Further, the fixing process shows nearly same result in measurement accuracy to the adjustment process, that is, $0.0316{\lambda}$ vs. $0.0326{\lambda}$. So, we can conclude the setup for autostigmatic null lens system must be constituted by means of the fixing process. Meanwhile, we introduce and define the alignment aperture on aspheircal mirror, which can be approximated as spherical zone for alignment of null lens system, and besides, we calculate the required fabrication accuracy of the zone for the necessary measurement accuracy.