• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.1
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• pp.206-213
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• 1996

Third order correlation funciton is to be advantageous to detect unique features embedded in various random signals that are undetectable with second order correlation or power spectrum. In this paper, we will introduce optical modulator which consists of a laser light source, 2-dimensional ultrasonic diffractor cell with signal controlling circuitry, and a CCD camera connected to personal computer for image processing. With this modulator, the third order correlaiton pattern of signal can be immediately obtained at the camera due to parallel nature of optical computing.

• Korean Journal of Optics and Photonics
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• v.3 no.4
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• pp.217-221
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• 1992

A micro lens system was designed for the modulator in optical fiber communication. One was the collimating lens which transferred the diffracted beam from optical fiber to the modulator. The other was the coupling lens which connected the modulated collimating beam to the optical fiber. The light source was He-Ne laser beam. The lens would be made of optical glass BK-7. We determined the tolerance of curvature radius, thickness and conic constant.

• Proceedings of the Optical Society of Korea Conference
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• 2002.11a
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• pp.192-193
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• 2002

In this paper we investigate the phase modulation efficiency in the electrooptic phase modulator using PPpinNN GaAs/AlGaAs W-type waveguide. The phase change is affected by the refractive index change taking place inside the depletion region. The behavior of the modulator can be understood in terms of two electric field-related and two carrier-related effects linear electrooptic, quadratic electrooptic, plasma, and bandgap shift. As a result, the phase modulation efficiency was measured about 34.6($^{\circ}$/V$.$mm) for the TE polarized light. The quadratic electrooptic coefficient R 5.82${\times}$10$\^$-15/($\textrm{cm}^2$/V$^2$) is Obtained ant the Phase efficiency Caused by the quadratic electrooptic effect is about 10 times larger than that from the conventional linear electrooptic effect.

• Proceedings of the Optical Society of Korea Conference
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• 2009.10a
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• pp.135-136
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• 2009

• Proceedings of the Optical Society of Korea Conference
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• 2007.02a
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• pp.72-73
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• 2007

• Proceedings of the Korean Magnestics Society Conference
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• 2008.12a
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• pp.313.2-313.2
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• 2008

• Journal of Information Display
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• v.3 no.3
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• pp.24-29
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• 2002

Liquid Crystal Spatial Light Modulators (LC-SLMs) provide many interesting applications in laser optics and opto-el ectronic systems, in addition to displays. Among them, three topics developed at Thales Research & Technology are reviewed: wavefront correction for laser beam control, microwave processing in radar systems and holography for TN-LCDs viewing angle compensation.

• ETRI Journal
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• v.41 no.1
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• pp.23-31
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• 2019

Since the late 20th century, there has been rapid development in the display industry. Only 30 years ago, we used big cathode ray tube displays with poor resolution, but now most people use televisions or smartphones with very high-quality displays. People now want images that are more realistic, beyond the two-dimensional images that exist on the flat screen, and digital holography-one of the next-generation displaysis expected to meet that need. The most important parameter that determines the performance of a digital hologram is the pixel pitch. The smaller the pixel pitch, the higher the level of hologram implementation possible. In this study, we fabricated the world-smallest $3-{\mu}m$-pixel-pitch holographic backplane based on the spatial light modulator technology. This panel could display images with a viewing angle of more than $10^{\circ}$. Furthermore, a comparative study was conducted on the fabrication processes and the corresponding holographic results from the large to the small pixel-pitch panels.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.64-67
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• 2004

The klystron-modulator(K&M) system of the Pohang Light Source(PLS) had been supplying high power microwaves for the acceleration of 2.5 GeV electron beams since October 2002. There are 12 sets of K&M systems to accelerate electron beams to 2.5GeV nominal beam energy. One module of the K&M system consists of an 80 MV S-band (2856 MHZ) klystron tube and the matching 200 MW modulator. In order to obtain electron beam of the consequently stability for linac, the pulse-to-pulse beam voltage regulation is less than $+/-0.5\%$. To get the reliable stability of the modulator which is less than $+/-0.5\%$, a charging section is improved in a modulator which has been operated with inverter power supply.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.4
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• pp.92-102
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• 2003

To detect electrical faults of a TFT (Thin Film Transistor) panel for the LCD (Liquid Crystal Display), techniques of converting electric field to an image are used One of them is the PDLC (polymer-dispersed liquid crystal) modulator which changes light transmittance under electric field. The advantage of PDLC modulator in the electric field detection is that it can be used without physically contacting the TFT panel surface. Specific pattern signals are applied to the data and gate electrodes of the panel to charge the pixel electrodes and the image sensor detects the change of transmittance of PDLC positioned in proximity distance above the pixel electrodes. The image represents the status of electric field reflected on the PDLC so that the characteristic of the PDLC itself plays an important role to accurately quantify the defects of TFT panel. In this paper, the image of the PDLC modulator caused by the change of electric field of the pixel electrodes on the TFT panel is acquired and how the characteristics of PDLC reflect the change of electric field to the image is analyzed. When the holding time of PDLC is short, better contrast of electric field image can be obtained by changing the instance of applying the driving voltage to the PDLC.