• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.4
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• pp.509-515
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• 2011

When a manufacturing system is designed, various kinds of evaluation methods are used for selecting the best alternative. Net present value, inner rate of return and payback period are popular quantitative measures for the economic assessment, but other qualitative measures should be considered for evaluation. The analytic hierarchy process(AHP) has been used as the popular method for the multi criteria decision making problem that considers both quantitative and qualitative criteria. This paper explains the process of economic assessment, and how to use the AHP for evaluating the designs of the assembly lines for lens module installed in mobile phone.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.9
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• pp.64-71
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• 1997

A new etching technique of meltback was investigated for GaAs lensed optical devices with selective windows opending in the LPE (liquid phase epitaxy) system. In the meltback process, the etch depth and the etch shape were controlled by the degree of under-saturation, etch time and other parameters. A GaAs/AlGaAs DH layer was grown on the selectively etched hemispherical well for optical device application such as lensed surface emitting LED. The regrowth process were related with the coolin grate and the well to well spacing. A novel surface emitting LED with hemispherical AlGaAs lens was fabricated using the meltbakc and regrowth as the key process for AlaAs lens array. The light emitting efficiency of the LED was upto three times higher than the similar structure LED without lens. The meltback and regrowth technique was applicable to manufacture the optical device in LPE.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.370-375
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• 2002

Recently, the interest on micro optical parts has increased rapidly with the development of technology related to microsystems. Among the optical parts, micro lens is one of the most broadly used micro parts. To mass-produce the micro lenses, it is very effective to use the mold insert and injection molding process. There are many methods to fabricate the mold insert for micro lenses: electroforming, etching, mechanical micromachining and so on. In this study, we fabricated the mold insert for micro lenses using a micro ball endmill to apply mechanical micromaching method and analyzed the effect of main process parameters such as spindle speed, feed rate, dwell time on the processed surface. Then, using fabricated the mold insert we fabricated the micro lenses through injection molding process.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.1
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• pp.35-43
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• 2008

Aviation obstacle lights including controller for the safe night aviation service have applied to high voltage transmission line of which height is from $60{\sim}180 m$, Fresnel lens made by Augustine Fresnel have been applied to light houses, These Fresnel lens were applied to aviation obstacle lights and have been universally used, It was reported that Fresnel lens for aviation obstacle light was used in the first place in Korea in 1987, LEDs have recently been applied to aviation obstacle lights, So, the optimum physical design is essential to the design of aviation obstacle light. In this study, optical and three dimensional modeling of LED module and globe lens were performed, And thermal analysis due to LED thermal source and service thermal condition in high voltage transmission line was performed and was analyzed comparing with experiments, The optimum design process of medium intensity LED aviation obstacle lights was constructed with three dimensional modeling, thermal analysis, and thermal experimental technique.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.95-98
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• 2006

LCD-BLU (Back Light Unit) is one of kernel parts of LCD unit. The fabrication method of a 3-D micro mold patterned with micro-lenses for the LGP (Light Guiding Plate), one of the most important parts of LCD-BLU, was presented. Instead of dot pattern made by etching, 3-D optical pattern design with $50{\mu}m$ micro-lens was applied in the present study. The micro-lens pattern fabricated by modified LiGA with thermal reflow process was applied to the optical design of LGP. The positive micro-lens patterned injection mold with different aspect ratios (i.e. 0.3 and 0.4) was fabricated with modified LiGA with thermal reflow process. The brightness of LCD-BLU increased as aspect ratio of micro-lens increased.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.5
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• pp.773-777
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• 2012

Recently UV laser micromachining processes is widely introduced to meet the needs of advanced components of IT, BT and ET industries. Due to the characteristics of non-contact and high-speed laser processing, UV laser micromachining is applied to manufacture very thin substrate such as polymer, metals and composite. These minimum line width obtained by UV laser micromachining is generally determined from laser wavelength, optical lens and its numerical aperture. In this paper we will show the lens effect of water droplet on the surface of workpiece to reduce the line width when UV laser light is irradiated and focused through the water droplet. Because of the refraction effect generated by the semi-spherical or spherical shape of water droplet, we can find smaller line width. And water droplet could not only protect thermal deformation, but also carry away burr around micro dent. Firstly fundamental theory of minimum line width was derived from relationship between the geometry of water droplet and laser light trace, and then experimental and simulation results will be finally compared to verify the effectiveness of water droplet lens effect of UV laser micromachining process.

• Transactions of Materials Processing
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• v.18 no.4
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• pp.310-316
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• 2009

Micro lens array(MLA) is widely used in information technology(IT) industry fields for various applications such as a projection display, an optical power regulator, a micro mass spectrometer and for medical appliances. Recently, MLA have been fabricated and developed by using a reflow method having the processes of micro etching, electroplating, micro machining and laser local heating. Laser thermal relaxation method is introduced in marking of microdots on the surface of densified glass. In this paper, we have proposed a new direct fabrication process using UV laser local thermal-expansion(UV-LLTE) and investigated the optimal processing conditions of MLA on the surface of negative photo-resist material. We have also studied the 3D shape of the micro lens obtained by UV laser irradiation and the optimal process conditions. And then, we made chrome mold by electroplating. After that, we made MLA using chrome mold by hot embossing processing. Finally, we have measured the opto-physical properties of micro lens and then have also tested the possibility of MLA applications.

• Journal of the Optical Society of Korea
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• v.19 no.3
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• pp.265-271
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• 2015

We propose a reactive mesogen (RM) lens array to obtain good focusing behavior along with a short focal plane, where the focusing behavior is switchable according to the polarization state of incident light. Polarization-dependent focusing behavior is obtained using a planoconvex RM microlens array on a planoconcave isotropic lens template. Even though the sagitta of our RM lens is high, to obtain the short focal length, the RM layer can be aligned well by introducing a top-down alignment effect, using a nanogrooved template. The optical noise due to the $moir{\acute{e}}$ effect generated by the nanogrooves on the surface of the planoconvex RM layer can be removed simply by overcoating a thin RM layer, which is self-aligned by the geometric surface effect, without an additional alignment process. We demonstrate a hexagonal-packed RM lens array that has a very high fill factor and symmetric phase profile, for an ideal lens.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.11
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• pp.1031-1040
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• 2014

In this paper, a new condition diagnosis algorithm for the lens injection molding process using various features extracted from cavity pressure, nozzle pressure and screw position signals is developed with the aid of probability neural network (PNN) method. A new feature extraction method is developed for identifying five (5), seven (7) and two (2) critical features from cavity pressure, nozzle pressure and screw position signals, respectively. The node energies extracted from cavity and nozzle pressure signals are also considered based on wavelet packet decomposition (WPD). The PNN method is introduced to build the condition diagnosis model by considering the extracted features and node energies. A series of the lens injection molding experiments are conducted to validate the model, and it is demonstrated that the proposed condition diagnosis model is useful with high diagnosis accuracy.

• The Journal of the Korea Contents Association
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• v.14 no.10
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• pp.1-9
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• 2014

Generally, integral image used for autostereoscopic 3d display is generated for flat lens array, but flat lens array cannot provide a wide range of view for generated integral image because of narrow range of view. To make up for this flat lens array's weak point, curved lens array has been proposed, and due to technical and cost problem, approximate surface lens array composed of several flat lens array is used instead of ideal curved lens array. In this paper, we constructed an approximate surface lens array arranged for $20{\times}8$ square flat lens in 100mm radius sphere, and we could get about twice angle of view compared to flat lens array. Specially, unlike existing researches which manually generate integral image, we propose an OpenCL GPU parallel process algorithm for generating real-time integral image. As a result, we could get 12-20 frame/sec speed about various 3D volume data from $15{\times}15$ approximate surface lens array.