• Journal of the Korean Institute of Telematics and Electronics
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• v.22 no.3
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• pp.68-76
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• 1985

A charge-coupled device (CCD) area image sensor has been demonstrated with an experi-mental 16$\times$16 prototype. The prototype is a vertical frame transfer charge.coupled imager using two-phase gate electrode structures. In this device, ion-implanted barriers are used for two -phase CCD, and NMOS process has been adopted. The total imaging setup consisting of optical lens, clock generators, clock drivels, staircase signal generators, and oscilloscope is easily achieved with the aid of PROM . English alphabets are displayed on the oscilloscope screen using the total imaging set-up. We measure charge transfer inefficiency and dark current for the fabricated devices.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.5
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• pp.409-417
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• 2016

It is well known that Morpho butterflies show distinctive, brilliant and iridescent colors and have micro-nano scale structures, instead of dyes and pigments, on their wings. This structural coloration is regarded as a novel technique to express color with a long lifetime, ease and precise tenability. Here, we studied optical multilayer thin films with thickness of several tens of nm ($TiO_2$ and $SiO_2$) and lens-shape micro-patterns. Fabrication and characterization of the multilayer stacking structure and the micro-pattern structure were performed and the films were analyzed via several optical measuring techniques. Finally, we discussed how the micro-pattern structure could enhance independence with color changes according to the viewing angle.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.4_2
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• pp.693-699
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• 2020

355nm UV pulse laser is irradiated on the surface of polyimide (PI) by LDW (Laser Direct Writing) method to produce a high sensitivity flexible humidity sensor using a simple one-step process. The LDW method continuously investigates 2-D CAD data using a galvano scanner and an F-lens. This method is non-contact, so it minimizes physical strain on the PI. Laser-induced graphene (LIG) produced by lasers has a high surface area due to its high flexibility and numerous pores and oxidizers compared to conductors. For this reason, it is highly useful as a flexible humidity sensor. The humidity sensor produced in this study was attached to the inside of a mask filter, which has become a hot topic recently, and its applicability was confirmed.The measurement of humidity measured the sensitivity, reactivity, stability and recovery behavior of the sensor by measuring changes in capacitance and resistance.

• Design & Manufacturing
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• v.15 no.3
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• pp.26-31
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• 2021

In this study, laser-induced periodic surface structure (LIPSS) was fabricated on Ni, Si, and GaAs samples using a flat-top beam with a uniform energy distribution that was fabricated using a Gaussian femtosecond laser with a mechanical slit and tube lens. Unlike the Gaussian beam, the flat-top beam has a uniform beam profile, therefore the center and the periphery of the fabricated LIPSS have similar line periodicity. In addition, LIPSS was obtained not only in metals but also in metalloids and metals and metalloid compounds by using the narrow pulse width characteristic of a femtosecond laser.

• Current Optics and Photonics
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• v.5 no.1
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• pp.8-15
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• 2021

An elliptical zone plate (EZP) array is important in off-axis optical systems because it provides two advantages. First, the residual beam and the main source are not focused in the same direction and second, the light from the observation plane is not reflected back towards the beam source. However, the fill factor of the previous EZP array was about 76% which was a little low. Hence, this EZP array could not collect the maximum amount of illumination light, which affected the overall optical performance of the lens array. In this study, we propose a new EZP array design with a 97.5% fill factor used in off-axis imaging system for enhancement of brightness and contrast. Then, direct laser lithography was used to fabricate the high fill factor EZP array by moving the XY linear stage of the system in a zigzag motion. The imaging properties of the proposed EZP array were experimentally verified at the focal plane and compared with the previous model.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.2
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• pp.107-115
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• 2011

Purpose: To design and fabricate the distributed auto edging machine for the development. Methods: We got the necessary data needed in design by using CAD. Based on the these data, we fabricated the trial product for the development of the distributed auto edging machine. Results: The patternless mode could be operated by receiving the eyesize data from the auto lay-outer with the RS232C transmission system and the pattern mode could be operated by setting the pattern on the left side of the machine. The distributed auto edging machine were composed with combinations of many elements; head, auto arm, pattern clamp and grinding wheels. The head part controlled the grinding of ophthalmic lens by operating the vertical and horizontal motors. The wheels part was comprised of glass mode, plastic mode, V-bevel mode and polish mode. The slide in the auto arm was equipped on the below of the patten and the slide could hold up the pattern which was rotated by fixed shaft. The pattern clamp could move the head part to the up and down or right or left way by the manual operation of optometrists. Conclusions: We could succeed in making the trial product by applying it to the development of the distributed auto edging machine which could be used as the patternless mode and pattern mode, selectively. Therefore, it was confidently expected that this product was very helpful for the optometrists to dispense the ophthalmic lens because of its cost-efficiency and convenience.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.6
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• pp.644-649
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• 2013

Today, there are lots of progresses in the field of lens researches, especially in the microlens fabrication. Unlike normal lenses, microlens has been widely used as a role of improving the performance of photonic devices which increase the optical precision, and also used in the fields of the display. In this paper, polymer microlenses with $300{\mu}m$ diameter were replicated through hot-embossing from nickel mold which was fabricated by micro-EDM. After hot-embossing process, the polymer microlenses have a rough surface due to the crater formed by micro-EDM process, which is projected onto the surface of the lenses. The surface of polymer microlenses was polished using solvent vapor to improve the surface roughness of the microlenses without changing their shape. In the experiment, the surface roughness was improved with the processing time and vapor temperature. Also, the roughness improvement was greatly affected by the solubility difference between polymer and solvent.

• Journal of Sensor Science and Technology
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• v.26 no.1
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• pp.39-43
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• 2017

Development of vision system as a nondestructive evaluation system can be very useful in screening the defective mechanical parts before they are assembled into the final product. Since the tens of thousands of the mechanical parts are used in an automobile carefully inspecting the quality of the mechanical parts is very important to maximize the performance of the automobile. To sort out the defective mechanical parts before they are assembled, auto parts fabrication companies employ various inspection systems. Nondestructive evaluation systems are getting rapidly popular among various inspection systems. In this study, we have developed a vision system to inspect the inside of the brake caliper, a part that is used to compose a brake which is the most important to the safety of the drivers and the passengers. In a brake caliper, a piston is pushed against the brake disk by oil pressure, causing a friction to damp the rotation of the wheel. Inside the caliper, a groove is positioned to adopt an oil seal to prevent the oil leaks. Inspecting the groove with our vision system, we could examine the existence of the contaminants which are normally the residual tiny pieces from the machining process. We used a high resolution GigE camera, 360 degree lens to look in the inside view of the caliper at once, and a special illumination system in this vision system. We used the edge detection technique to successfully detect the contaminants which were in the form of small metal chips. Labview graphical program was used to process the digital data from the camera and to display the vision and the statistics of the contaminants. We were very successful in detecting the contaminants from the various size calipers. We think we are ready to employ this vision system to the caliper production factories.

• Korean Journal of Optics and Photonics
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• v.10 no.1
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• pp.73-79
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• 1999

Semiconductor optical switch modules of 1$\times$2, 1$\times$4, and 4$\times$4 types for 1550 nm optical communication systems were fabricated by using laser welding technique, embodying in 30-pin butterfly package. For better coupling efficiency between switch chip and optical fiber, tapered fibers of 10~15mm lens radii were used, which provided up to 60% optical coupling efficiency. With the help of new laser hammering process, we could recover the lost optical power almost completely up to average 82% of initially obtained power. The fabricated optical switch modules showed good thermal stability of less than 5% degradation even after 200 times thermal cycling test. The 2.5 Gbps optical transmission characteristics of the 4$\times$4 switch module showed low sensitivities of less than -30dB for all possible switching paths. The transmission penalties of 1$\times$2 switch module at $10^{-10}$ BER were 0.6dB and 0.7dB for 50Xm and 90 Km optical fibers, respectively.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.1
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• pp.73-76
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• 2010

The issue of inspection and characterization of microstructures has emerged as a major consideration in design, fabrication, and detection of MEMS devices. However, the conventional measurement techniques, including scanning electron microscopy (SEM) imaging, atomic force microscopy (AFM) scanning, and mechanical surface profiler, require often destructive process or may be difficult to measure with a wafer scale. In this paper, we characterize the surface profiles of microstructures using an optical scanner based on a DVD pick-up module. Scanning images of the microstructures are successfully generated using the intensity of reflected light from different depths of the surface profiles, based on the focus error signal (FES) from photodiodes. It is shown that the proposed optical scanner can be used as an alternative measurement system with high performance and low cost, compared to conventional measurement techniques.