• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
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• pp.600-602
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• 2005

Recently image display devices have become large and high quality. To control the qualities of the component, measurements of the shape and thickness of a plate glass has been required. In order to measure the shape of the specular objects, Non-Contact Optical Sensor using Hologram laser unit was proposed. The sensor has a optical system that is composed of a Hologram laser and objective lens used for CD Player, and the sensor showed high performance for measuring the shape and thickness of transparent plates. In the sensor, the temperature of the sensor body is controlled by TEC(Thermoelectric Cooler). In this paper, we proposed the measuring method to make better performance of sensor using focus error signal of a hologram laser unit. It can measure the shape and the thickness of transparent objects with the s-type focus error signal which is generated by the sensor while it goes to the object.

• 한국전기전자재료학회논문지
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• 제31권4호
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• pp.193-197
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• 2018

The ratio of the period of a diffractive element to the input beam size is a critical parameter in a diffractive beam shaper. We measured and calculated the Fraunhofer diffraction patterns of a periodic hologram with an input beam size similar to the period of the hologram. The measured intensities show very complicated patterns and are strongly dependent upon the center position of the laser beam relative to the hologram. Using a diffraction formula for a periodic hologram, we calculated the diffracted light intensities and fit them to the measured ones. The measured and calculated intensities are in good agreement even when the beam diameter of the incident laser is similar to the period of the hologram. We can therefore use this formula to estimate the output of a periodic beam shaper even under such an extreme condition.

• 한국전기전자재료학회논문지
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• 제24권7호
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• pp.578-583
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• 2011

We report on the design of a holographic homogenizer composed of a periodic hologram and a condensing lens. If the hologram is periodic, the homogenizer is free from the alignment error of the incident laser beam. Holographic homogenizer also has an advantage of the flexibility in the size of the target beam. We calculated theoretically the Fraunhofer diffracted wave function when a rectangular laser beam is incident on a periodic hologram. The diffracted wave is the sum of sinc functions at regular distance. The width of each sinc function depends on the size of the incident laser beam and the distance between the sinc functions depends on the period of the hologram. We calculated numerically the diffracted light intensity for various ratios of the size of the incident laser beam to the period of the hologram. The results show that it is possible to make the diffracted beam uniform at a certain value of the ratio. The uniformity is high at the central part of the target area and low near the edge. The more sinc functions are included in the target area, the larger portion of the area becomes uniform and the higher is the uniformity at the central part. Therefore, we can make efficient homogenizer if we design a hologram so that the maximum number of the diffracted beams may be included in the target area.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 C
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• pp.1430-1431
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• 2006

We investigated the formation of 2-dimension hologram grating by means of selective etching characteristic and photo-expansion effect according to photo irradiation on amorphous As-Ge-Se-S thin film. By method of phase holography, we made the 2-dimensional hologram grating by each (S:P) and ($+45^{\circ}:-45^{\circ}$) polarized beam with DPSS laser(532nm) and He-Ne laser(632nm). A recording property was observed at each polarized beam through 2-dimensional hologram surface relief grating. Chalcogenide thin film was etched selectively by NaOH solution after the formation of 1-dimensional diffraction grating. And then etched sample was rotated 90 degree to fabricate 2 dimensional hologram grating. We found that it was observed the formation of 2-dimensional hologram grating by AFM(Atomic Force Microscopy).

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
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• pp.579-581
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• 2006

Flat panel image display devices such as TFT LCD and PDP have required more large area and high quality control components. To control the qualities of the components, measurements of the flatness of a plate glass has been required. In order to measure the shape of the specular objects, Non-Contact Optical Sensor using Hologram laser unit was proposed. The sensor has a optical system that is composed of a Hologram laser and objective lens. The temperature of the sensor body is controlled by TEC(Thermoelectric Cooler) to maintain the same wavelength of the diode laser. In this research, we proposed the calibration scheme to make sensor real time measuring sensor. From the experimental results we see that the proposed sensor unit can measure the position of the glass surface in rial time.

• 전자공학회논문지T
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• 제35T권3호
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• pp.1-8
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• 1998

본 논문에서는 레이저 다이오드, 포토 다이오드, 그레이팅 렌즈, 빔 스프릿터가 반도체 공정으로 직접화된 홀로그램 레이저 다이오드와 4 와이어 부동형 엑츄에이터를 이용하여, 시장성이 풍부한 일반 오디오용 광학 픽업을 설계하였다. 또한, 이러한 홀로그램 레이저 다이오드의 특성을 이용하여 초간편 광학계를 구현하므로서, 기존외 제품 대비 조립성과 생산성을 향상시키고, 취부 부품의 수를 줄이고 형상을 단순화하였다.

• Journal of the Optical Society of Korea
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• 제20권4호
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• pp.524-529
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• 2016

Diagnostic sensors are demanded during plasma processes. Holograms of plasma taken with laser light without a reference beam were used to monitor behaviors of charged particles produced in nitrogen plasma as a function of electrode temperature ranging between 50 and 300℃. Holograms were characterized as a function of the pixel sum and grayscale value. Pixel sum calculated in identified grayscale ranges strongly correlated with ion density and emitted light intensity measured with a langmuir probe and optical emission spectroscopy, respectively. The performance was further evaluated with data acquired as a function of N₂ and NH₃ flow rates and improved correlations were observed in the new grayscale range. The confirmed correlations indicate that a hologram is a viable means to diagnose behaviors of plasma particles such as ions. Underlying principles are discussed in view of particle and charge composing vacuum and light.

• 한국통신학회:학술대회논문집
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• 한국통신학회 1986년도 추계학술발표회 논문집
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• pp.194-197
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• 1986

In this paper, for the curvature correction on the scanning plane in laser scanning system, aberration correction method using holographic optical element is suggested. Holoens is selected as a type of holographic zone plate which has aberration correction property. And hologram recording condition is analyzed to find fo property. This hololens is implemented by computer-generated hologram technique. Laser scanning system is organized using desinged hololens and scanning properties of this system are investigated. Using this method optical system structure in laser scanning system can be simplified satisfying both scan linearity and field flatness.

• 대한전자공학회논문지
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• 제23권2호
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• pp.257-263
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• 1986

A laser scanner utilizing a computer-generated hologram(CGH) as beam deflector is reported. The CGH optical element has been used mainly for under-filled scanning. Here, a CGH optical element for overfilled scanning is proposed. It can achieve, under the same limitation of fabrication accuracy, better resolution and longer scan length than those for under-filled scanning. Measured scanning characteristics of the laser scanner show the scan length of 40 cm and the beam diameter of 100\ulcorner, where the designed minimum distance between the lines of CGH is 8\ulcorner.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 추계학술대회 논문집
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• pp.131-132
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• 2008