• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.2
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• pp.141-149
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• 2015

In the fabrication of electronic circuits used in electronic products, molybdenum thin films are deposited on semiconductors to prevent oxidation. During the deposition, the presence of a particle or dust at the interface between the thin film and substrate causes the decrease of adhesion, performance, and life cycle. In this study, a damage measurement targeting two kinds of glass substrate, with and without particles, was performed in order to measure the change in the molybdenum thin film deposition area in the presence of a particle. Clean and dirty molybdenum thin film specimens were fabricated and directly deposited on a substrate using the sputtering method, and a reflection-type digital holographic interferometer was configured for measuring the damage. Reflection-type digital holography has several advantages; e.g., the configuration of the interferometer is simple, the measurement range can be varied depending on the magnification of a microscopic lens, and the measuring time is short. The results confirm that reflection-type digital holography is useful for the measurement of the damage and defects of thin films.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.12
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• pp.1130-1135
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• 2015

The bond pull test is the most widely used technique for the evaluation and control of wire bond quality. The wire being tested is pulled upward until the wire or bond to the die or substrate breaks. The inspector test strength of wire by manually and it takes around 3 minutes to perform the test. In this paper, we develop a 3D vision system to measure 3D position of wire. It gives 3D position data of wire to move a hook into wires. The 3D measurement method to use here is a confocal imaging system. The conventional confocal imaging system is a spot scanning method which has a high resolution and good illumination efficiency. However, a conventional confocal systems has a disadvantage to perform XY axis scanning in order to achieve 3D data in given FOV (Field of View) through spot scanning. We propose a method to improve a parallel mode confocal system using a micro-lens and pin-hole array to remove XY scan. 2D imaging system can detect 2D location of wire and it can reduce time to measure 3D position of wire. In the experimental results, the proposed system can measure 3D position of wire with reasonable accuracy.

• Journal of Korean Ophthalmic Optics Society
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• v.1 no.1
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• pp.93-102
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• 1996

The optical system of lens must be designed to tramsmit light over wide wavelength range and to have lower reflectivity in order to obtain higher spectral transmittance. However, the reflection color light appears due to the remain-reflection light in any optical system of lens. The wavelength of the reflection color light can be controlled by the structure of the number of layers, thickness of layer, reflective index, wavelength of incidence, and substrate etc. In the optical systems of the single layer and the double layers, the reflection color light appears in the condition of the anti-reflection of ${\lambda}s/{\lambda}$ = 1.0 by the color mixture of the remain-reflection lights in the ranges of the longer wavelength side and the shorter one of the ${\lambda}s/{\lambda}$ = 1.0, and of the double layers and triple layers, the reflection color light positioned at P1 < ${\lambda}s/{\lambda}$ < P2 appears in the condition of the antireflection of ${\lambda}s/{\lambda}$ = $PI{\ll}1$ and $P2{\gg}1$. In the optical system of the multi-layers, many antireflection points are existed at the various s/ values, and the reflection color light by the color mixture of the remain-reflection lights in the ranges except for the antireflection points.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.3 s.357
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• pp.105-110
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• 2007

We have built the millimeter-wave passive imaging system with a lens and mechanical scan antenna. The lens was designed based on optical theory in order to focus millimeter-wane. A full image was taken from image points scanned by Placing antenna at the representative focal plane selectively. An integrated antenna array device for low-loss and low-noise with the array of 4 by 1, where components such as antenna, balun, MMIC, and detector were assembled on a sin91e substrate, and a fermi tapered slot antenna with high-gain and low-side lobe were used for elements of this millimeter-wave passive imaging system. Two dimensional antenna arrangement on focal plane was achieved in this imaging system.

• Journal of the Korean Ceramic Society
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• v.50 no.6
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• pp.454-459
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• 2013

Recently, remote phosphors have been reported for application to white LEDs to provide enhanced phosphor efficiency compared with conventional phosphor-based white LEDs. In this study, a remote phosphor was produced by coating via screen printing on a glass substrate with different numbers of phosphor coating. The paste consists of phosphor, lowest softening glass frits, and organic binders. The remote phosphor could be well controlled by varying the phosphor content rated paste. After mounting the remote phosphor on top of a blue LED chip, CCT, CRI, and luminance efficiency were measured and values of 5300 K, 62, and 117 lm/W were respectively obtained in the 80 wt% phosphor with 3 coating layers sintered at $800^{\circ}C$.

• Korean Journal of Optics and Photonics
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• v.30 no.4
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• pp.146-153
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• 2019

The exposure system is a device that transfers a circuit pattern to a desired location. To display patterns on a substrate without deforming the optical characteristics, the characteristics of the optical exposure system are very important. Therefore, to form a microcircuit pattern, a small divergence angle should impinge on the irradiation area. Also, since the light from the source must react uniformly with the photosensitizer, it must have high luminance efficiency and uniformity of illumination. In this paper a parabolic reflector and an aspherical lens were designed to solve the problem of narrow-angle implementation, and it was confirmed by simulation analysis after their arrangement that the beam angle, uniformity, and maximum illuminance satisfied the target performance.

• Journal of the Korean institute of surface engineering
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• v.41 no.3
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• pp.88-93
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• 2008

Ir-Re thin films with Ti interlayer were deposited onto the tungsten carbide substrate by ion beam assisted DC magnetron sputtering. The Ir-Re films were prepared with targets of having two atomic percent of 7:3 and 5:5. The microstructure and surface analysis of the specimen were conducted by using SEM, XRD and AFM. Mechanical properties such as hardness and adhesion strength of Ir-Re thin film also were examined. The interlayer of pure titanium was formed with 100 nm thickness. The film growth of Ir-30at.%Re was faster than that of Ir-50at.%Re in the same deposition conditions. Ir-Re thin films consisted of dense and columnar structure irrespective of the different target compositions. The values of hardness and adhesion strength of Ir-30at.%Re thin film coated on WC substrate were higher than those of Ir-50at.%Re thin film.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.10
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• pp.745-753
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• 2013

Performance of organic light-emitting diodes incorporating microlens array was simulated using a Light Tools software. Use of microlens array can help the light to escape out of the device. We simulated a reference device that is consisted of reflection layer, emissive layer, and flat transparent substrate. And in this reference device, outcoupled efficiency of 22% was obtained. Several shapes of microlens were applied such as hemisphere, trapezoid, cone, and rectangular parallelepiped. The results showed the improvement of outcoupled efficiency of the device with microlens compared to that of the reference one. And from the analyses of the simulated data, the obtained appropriate shape of microlens is hemisphere, and the improvement of the device with hemispherical lens is 57% higher than that of the reference one.

• Korean Chemical Engineering Research
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• v.47 no.3
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• pp.316-320
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• 2009

UV curable hard and color coatings were formed on polycarbonate(PC) films. The coating materials were composed of a commercially available end-capped polyester(EB830), diacrylate monomer(HDDA), silicon acrylate, photoinitiator, and organic dye as a coloring agent. The surface properties of coating films were evaluated, and the influences of the compositions of coating materials were investigated. The coating films showed high transmission and good adhesion between coating layer and PC substrate. And the coating films exhibited higher hardness than bare PC film. The coating films with various colors were obtained by wet process, and the clear and color window lenses for mobile phone were prepared successfully.

• Transactions of the Society of Information Storage Systems
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• v.7 no.1
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• pp.19-24
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• 2011

Holographic Data Storage System, one of the next generation data storage devices, is a 2-dimensional page oriented memory system using volume holograms in writing and retrieving process. Recently photopolymer with disc type substrate was selected as a media for the Holographic Data Storage System. The disc tilt occurs when the media rotates and the external disturbance applies. The disc tilt causes the change of the angle between the reference beam and the media, the data cannot be retrieved with the right angle or other data page is retrieved. The tilt is generated in a 2-axis direction (tangential, radial). The tangential tilt direction is the same with the multiplexing plane, while the radial tilt direction is a perpendicular to the multiplexing plane. In this research we propose 2-axis tilt angle servo system. The tilt errors are measured by using external photo detector and the additional red laser. Then the tangential direction tilt is compensated by using the galvano mirror. Also the radial direction tilt is compensated by the rotating prism between the relay lens in the reference field. Finally we confirm the compensation results through the Signal to Noise Ratio(SNR) and Bit Error Rate(BER).