• Proceedings of the KSME Conference
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• 2000.04a
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• pp.411-414
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• 2000

Optical Triangulation Probes (OTPs) are widely used for their simple structure. high resolution, and long operating range. However, errors originating from speckle, inclination of the object, source power fluctuation, ambient light, and noise of the detector limit their usability. In this paper, we propose new design criteria for an error-reduced OTP. The light source module for the system consists of an incoherent light source and a multimode optical fiber for eliminating speckle and shaping a Gaussian beam Intensity profile. A diffuse-reflective white copy paper, which is attached to the object, makes the light intensity distribution on the change-coupled device(CCD). Since the peak positions of the intensity distribution are not related to the various error sources, a sub-pixel resolution signal processing algorithm that can detect the peak position makes it possible to construct an error-reduced OTP system

• Polymer(Korea)
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• v.31 no.2
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• pp.148-152
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• 2007

The prototype of color fitters for the liquid crystal displays (LCD) using cholesteric liquid crystal monomers was produced. Cholesteric liquid crystal is characterized by the unique optical features of selective reflection, which is due to the helical twisting structures of LCs comparable to the wavelength of the incident light under certain conditions of substrate treatment. In the results of the experiment, cholesteric films for red, green, and blue light reflections respectively were produced and the viewing angle dependence of these films were investigated. Reflective light of red and green films shifted to shorter wavelength regions as viewing angle becomes greater, but blue one shifted very little. Periodic micrometer-sized half-spherical photoresist formed by thermal reflow method after photo-lithography was patterned on glass substrates. The viewing angle dependence of reflective light colors of red, green, and blue films on the patterned substrates compared with those on no patterned substrates was investigated. We could confirm the dependences were much smaller on the patterned substrates by bare eyes and Lab-color coordination methods qualitatively.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.820-823
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• 2004

We present high reflective anode for top emission OLED. Anode consists of two layers, which are increasing the ability of hole injection and the reflectivity of emitted light. Thin Cr is deposited on AlNd that has a high thermal resistance and reflectivity. The current-voltage characteristics of Cr(30${{\AA}}$)/AlNd(1000${{\AA}}$) anode are poor but these of Cr(50${{\AA}}$)/AlNd(1000${{\AA}}$) anode are superior to these of Cr(30${{\AA}}$)/AlNd(1000${{\AA}}$) and the work function of cr(50${{\AA}}$)/AlNd(1000${{\AA}}$) is higher that of Cr(30${{\AA}}$)/AlNd(1000${{\AA}}$).

• Current Photovoltaic Research
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• v.8 no.1
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• pp.1-5
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• 2020

The most important factor in enhancing the performance of an optical device is to minimize reflection and increasing transmittance of light for a broad wavelength range. The choice of appropriate coating material is crucial in decreasing reflection losses at the substrate. The purpose of this review is to highlight anti-reflection coating (ARC) materials that can be applied to silicon solar cell and glass substrate for minimizing reflection losses. The optical and electrical behavior of ARC on a substrate is highly dependent on thickness and refractive index (RI) of ARC films that are being deposited on it. The coating techniques and performance of single and multi-layered ARC films after coated on a substrate in a wide range of wavelength spectrum will be studied in the paper.

• ETRI Journal
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• v.29 no.6
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• pp.817-819
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• 2007

A low-stress organic polymer membrane is proposed as a deformable mirror that can be incorporated into a cellular phone camera to achieve auto focusing without motor-type moving parts. It is demonstrated that our fabricated device has an optical power of 20 diopters and can switch focus in 14 ms. The surface roughness of the organic membrane is measured around 15 nm, less than ${\lambda}$/20 of the visible light. With curve fitting, we found that the actuated membrane is almost parabolic in shape, which leads to less aberration than spherical surfaces. It is suitable for reflective-optics systems.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.535-536
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• 2006

Researches about micro technology travel lively in these days. Such many researches are concentrated in the field of materials and a process field. But properties of micro materials should be known to give results of research developed into still more. In these various material properties, reliability data such as mechanical, optical, thermal property, etc is the basic property. In this paper, it is measured that is material properties of main BLU(Back Light Unit) components in LCD(Liquid Crystal Display). The pattern shape of prism sheet, diffuser film and reflective plate are measured by variable 3D scanning equipments. It is researched which is the method to measure an optimal 3D pattern shape in each components.

• Journal of the Optical Society of Korea
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• v.19 no.5
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• pp.494-502
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• 2015

This paper introduces methods to measure vibration using a fringe pattern. These methods use variations of a fringe pattern in reflective monochromatic interferometry, without additional components. With the proposed methods we measured the vibrations of four waveform with amplitude 100 nm. When the vibrational amplitude is greater than a quarter wavelength of the light employed, however, the measured results are distorted due to ambiguity. Thus we propose advanced methods to solve this problem, and also measure the vibrations of two waveformswith an amplitude of $1{\mu}m$. To verify the performance of the proposed methods, we compare the results to those from an accelerometer. Multifrequency vibrations of 1, 5, 10, and 20 Hz are measured by both techniques, and the results compared in the frequency domain.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.5
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• pp.263-266
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• 2006

An optical microphone was developed using a dual-core multi-mode fiber block and a membrane type micromirror. The fiber block serves as a compact optical head, and the micromirror as a reflective diaphragm. The micromirror is designed to be suspended through a silicon bar connected t a frame, allowing for displacement induced by acoustic waves. The optical head is implemented by integrating two multi-mode fibers in a single block, and used to transfer light signals between it and the diaphragm. For the assembled microphone, its static characteristics were observed to reveal the operating point defined as the optimum distance between the optical head and the diaphragm. And its dynamic response was tested to exhibit a frequency bandwidth of 3 kHz with the variation of $\sim5dB$.

• Journal of the Korean institute of surface engineering
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• v.32 no.3
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• pp.401-405
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• 1999

Reflective silver films with high quality were prepared on polyester substrate by using sputter deposit on techniques. Best reflectivity thin films of silver were produced with process parameters of $10^{-6}$ Torr as base pressure, 50 W as R.F. power, 5 mTorr as working pressure, and 10 sccm as Ar flow rate. Being deposited with an R.F. power of 50 W, Ag films revealed the highest 96.3 % reflectance as illuminated with a light of 700 nm wavelength. The adhesion of sample films showed as high as 14 to $20{\;}kg/\textrm{cm}^2$, which is suitable for industrial purposes. Their film crystallinity and orientation resulted in the planes of (111) and (200) for the growth with a preferred orientation of <111>, in general. The cross-sections of thin film specimens showed columnar structures. It is noted that columns became coarsened and less dense as R.F. power increased, resulting in a low reflectivity for the product film.

• Journal of the Optical Society of Korea
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• v.12 no.4
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• pp.359-363
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• 2008

A novel WDM-PON system delivering bidirectional 1.25-Gbps data and broadcasting data is proposed. A subcarrier signal modulates optical carriers of a Fabry-Perot-laser-diode based broadband light source to broadcast to all users. Reflective semiconductor optical amplifiers are used as modulators for the baseband data at both the optical line terminal and the remote optical network unit for a channel. Bit error rate and error vector magnitude were measured to demonstrate the proposed scheme.