• Korea-Australia Rheology Journal
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• v.19 no.3
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• pp.171-176
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• 2007

LCD-BLU (Liquid Crystal Display-Back Light Unit) of medium size is usually manufactured by forming numerous dots with $50{\sim}300\;{\mu}m$ in diameter by etching process and V-grove shape with $50\;{\mu}m$ in height by mechanical cutting process. However, the surface of the etched dots is very rough due to the characteristics of the etching process and V-cutting needs rather high cost. Instead of existing optical pattern made by etching and mechanical cutting, 3-dimensional continuous micro-lens of $200\;{\mu}m$ in diameter was applied in the present study. The continuous micro-lens pattern fabricated by modified LIGA with thermal reflow process was tested to this new optical design of LGP. The manufacturing process using LIGA-reflow is made up of three stages as follows: (i) the stage of lithography, (ii) the stage of thermal reflow process and (iii) the stage of electroplating. The continuous micro-lens patterned LGP was fabricated with injection molding and its test results showed the possibility of commercial use in the future.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.4_1
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• pp.517-527
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• 2023

Many techniques have been proposed and investigated for microlens array manufacturing in three-dimensional (3D) structures. We present fabricating a microlens array using selective laser etching and a CO₂ laser. The femtosecond laser was employed to produce multiple micro-cracks that comprise the predesigned 3D structure. Subsequently, the wet etching process with a KOH solution was used to produce the primary microlens array structures. To polish the nonoptical surface to the optical surface, we performed reflow postprocessing using a CO₂ laser. We confirmed that the micro lens array can be manufactured in three primary shapes (cone, pyramid and hemisphere). Compared to our previous study, the processing time required for laser processing was reduced from approximately 1 hour to less than 30 seconds using the proposed processing method. Therefore, micro lens arrays can be manufactured using our processing method and can be applied to mass productionon large surface areas.

• Korean Journal of Optics and Photonics
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• v.16 no.6
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• pp.508-515
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• 2005

We propose a fabrication method for refractive lens by variable velocity moving mask lithography and slit pattern. Distribution of exposure dose should be controlled for the curved photoresist surface that works as a refractive surface. We analyze theoretically the distribution of exposure dose by change of moving velocity, moving direction of mask and the shape of mask pattern, and confirm for the curved surface experimentally. The lens could have sag height of a few of hundreds ${\mu}m$, by using thick photoresist or Deep RIE process.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.18 no.6
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• pp.636-641
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• 2009

Recently, expansion of micro-technology parts requires micro-precision machining technology. Micro-groove machining is important to fabricate micro-grating lens and many micro-parts such as microscope lens, fluidic graphite channel etc. Conventional groove fabrication methods such as etching and lithography have some problems in efficiency and surface integrity. But, mechanical micromachining methods using single crystal diamond tools can reduce these problems in chemical process. For this reason, microfabrication methods are expected to be very efficient, and widely studied. This study deals with machinability in micro-precision V-grooves machining of nickel plated layer using non-rotational single crystal diamond tool and 3-axis micro stages. Micro V-groove shape, chip formation and tool wear were investigated for the analysis of machinability of Ni plated layer.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.617-618
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• 2013

• Journal of the Korean Society for Precision Engineering
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• v.20 no.5
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• pp.11-18
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• 2003

• Journal of The Korean Astronomical Society
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• v.24 no.1
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• pp.1-12
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• 1991

The mathematical properties of gravitational lens equations are examined in the frame work of gravitational micro-lensing effects. The caustics of the gravitational lens may be defined in terms of "cusp" and "folding" in general. In some cases for overfocussing, however, the critical curves (caustics) have no cusp and no folding. If the observer is in the overfocussed region, he may not see any lensed image.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.10
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• pp.19-24
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• 2007

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.383-384
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• 2009

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.167-168
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• 2010