• Korean Journal of Optics and Photonics
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• v.33 no.6
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• pp.267-274
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• 2022

In this paper, we report the design and fabrication of binary diffractive optical elements (DOEs) for random-dot-pattern projection for Schlieren imaging. We selected the binary phase level and a pitch of 10 ㎛ for the DOE, based on cost effectiveness and ease of manufacture. We designed the binary DOE using an iterative Fourier-transform algorithm with binary phase optimization. During initial optimization, we applied a computer-generated pseudorandom dot pattern of uniform intensity as a target pattern, and found significant intensity nonuniformity across the field. Based on the evaluation of the initial optimization, we weighted the target random dot pattern with Gaussian profiles to improve the intensity uniformity, resulting in the improvement of uniformity from 52.7% to 90.8%. We verified the design performance by fabricating the designed binary DOE and a beam projector, to which the same was applied. The verification confirmed that the projector produced over 10,000 random dot patterns over 430 mm × 430 mm at a distance of 5 meters, as designed, but had a slightly less uniformity of 84.5%. The fabrication errors of the DOE, mainly edge blurring and spacing errors, were strong possibilities for the difference.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.5
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• pp.82-88
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• 2007

This work is to fabricate a precise optical fiber array using polymer composite for optical interconnection. Optical fiber array has to satisfy low optical loss requirement less than 0.4 dB according to temperature change. For this purpose, design criteria for an optical fiber array was derived. The coefficient of thermal expansion of silica particulate epoxy composites was affected by volume fraction of silica particles. And also, elastic modulus of silica particulate epoxy composites was affected by volume fraction of silica particles. To obtain the coefficients of thermal expansion below $10{\times}10E-6/^{\circ}C$ and elastic modulus more than 20 GPa , we chose the volume fraction more than 76%. Using silica particulate epoxy composites with the volume fraction 76%, 8-channel optical fiber array with dimensional tolerances below $1\;{\mu}m$ was manufactured by transfer molding technique using dies with the uniquely-designed core pin and precisely-machined zirconia ceramic V block. These optical fiber arrays showed optical loss variations within 0.4 dB under thermal cycling test and high temperature test.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.213-216
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• 2007

LGP (light guide plate) of LCD-BLU (Liquid Crystal Display - Back Light Unit) is one of the major components which affects the product quality of LCD. In the present study, the optical patterns of LGP(2.2") are manufactured by three different methods, namely, laser ablation, chemical etching and LiGA - reflow, respectively. The pattern surface images and roughness of mold and product were compared to check the optical characteristics. From the results of measurement the optical patterns fabricated by LiGA - reflow method showed the best geometric structure as intended in design and the lowest roughness among those.

• Korean Journal of Optics and Photonics
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• v.24 no.1
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• pp.17-22
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• 2013

High performance plastic optical fiber (POF) $N{\times}N$ star couplers are implemented based on fusing and combining technology. A set of cladding-removed POFs are fused into a solid body by heating and pressing them together to form the transition region between the input and output sides. The operation principle of the proposed star coupler is explained based on ray optics. To demonstrate the performance of the device, $2{\times}2$, $4{\times}4$ and $6{\times}6$ type POF couplers were fabricated and characterized. Performances of the POF star couplers were evaluated in terms of the flatness of the coupling ratios and excess losses.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.54 no.3
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• pp.148-154
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• 2005

Various methods for analyze optical components which are necessary before the fabrication of optical circuit component and as its applications, designing method of Wavelength Division Multiplexer(WDM) filter using arrayed-waveguide grating(AWG) is paper. In the case of analyzing uniform optical waveguide, effective index method(EIM), harmonic expansion method are used, and in the case of non-uniform optical waveguide, beam propagation method(BPM) are used. In this paper, to use arrayed-waveguide grating as WDM filter of centered wavelength of $1.55{\mu}m$ and wavelength spacing of 0.8nm, all of the parameter of AWG is calculated by the HEM and the BPM using EIM. As a result of calculation, free spectral range is 12.8nm, focal length $9336.55{\mu}m$, path difference $129.36{\mu}m$ and the number of slab waveguide 91 when the distance of core center to center on row land circle is $20{\mu}m$.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.7
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• pp.109-116
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• 1998

In this work was produced and analyzed a z-cut Ti:LiNbO$_{3}$ optical waveguide which applies for various optical devices.A waveguide channel with a thickness 8 .mu.m and a length 66,000.mu.m and a mach-zehnder interferometer type waveguide were fabricated at a diffusion temperature 1050.deg. C for 6-8hours in a wet $O_{2}$ environment. The resulting Ti:LiNbO$_{3}$ optical waveguide was measured to have a Ti-strip thickness of 950.angs. and low loss. Surfaces and cross-sections of a fabricated waveguide were analysed. The mode pattern anaysis revealed that the waveguide showed a single mode at a 1550nm wavelength. The effective dimension of the waveguide was calculated by measuring a gaussian profile; Wx=10.95.mu. and Wy=9.14.mu.m. a propagation loss, of 0.50dB/cm for a TM mode and 0.45dB/cm for a TE mode, was low enough to be accepatable for optical devices.

• Journal of the Optical Society of Korea
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• v.4 no.2
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• pp.79-85
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• 2000

The main purpose of this paper is to present the potential of photovoltaic systems using holographic solar concentrators. A hologram used here focuses light, spectrally splits it and diverts unwanted infrared heat away from the solar cell. The output of the hologram appears as a perpendicular thin spectral line and is displaced to solar cells on both sides. To obtain optimum design conditions we used the coupled wave theory and the vector ray tracing method. The measured data showed that the diffraction efficiency was 75 ％ and the spectral bandwidth was 350 nm.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1932-1938
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• 2003

We have applied spectroscopic ellipsometry to investigate $high-{\kappa}$ dielectric thin films and correlate their optical properties with fabrication processes, in particular, with high temperature annealing. The use of high-k dielectrics such as $HfO_{2}$, $Ta_{2}O_{5}$, $TiO_{2}$, and $ZrO_{2}$ as the replacement for $SiO_{2}$ as the gate dielectric in CMOS devices has received much attention recently due to its high dielectric constant. From the characteristics found in the pseudo-dielectric functions or the Tauc-Lorentz dispersions, the optical properties such as optical band gap, polycrystallization, and optical density will be discussed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.115-118
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• 2002

The purpose of this paper is to design a pick-up for the small form factor optical disk drive and to fabricate a micro-compensatory lens for the pick-up using the micro-compression molding process. At design stage, the optical elements including the objective lens and the compensatory lens are miniaturized. The height of pick-up and free working distance are designed as 2mm and 0.2% respectively. To analyze the fabricated micro-compensatory lens, the system was analyzed using the surface profile of the fabricated micro-compensatory lens and CODE V which is commercial software. The RMS wave front aberration of the system using fabricated micro-compensatory lens is 0.01677λ which is lower than Marechal's criterion, 0.07λ.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.123-127
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• 2002

In order to set up the design rule of micro optical bench, optical coupling efficiencies of two sets of test benches are calculated. Simple linear connections of incoming and outgoing optical fibers with and without ball lenses are designed. Positional errors that are possible in actual fabrication processes are considered in the calculations and their tolerances are determined from 3dB conditions. For a simple fiber-to-fiber connection, the working distance is limited to $2.7\mu\textrm{m}$ and tilt error $5.8^{\circ}$. When ball lenses are located in front of each fiber, the working distance can be extended over $60\mu\textrm{m}$ , but the positional errors have the strong interaction among position parameters and thus should be considered simultaneously for tolerance design.