• Proceedings of the Optical Society of Korea Conference
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• 2007.07a
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• pp.275-276
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• 2007

A multiplex recording and reading technique in photopolymer are presented In order to record the polarization gratings, polarization-sensitive materials, in which linear birefringence is induced by irradiating the polarized light, are necessary. We checked orthogonal and independence of laser. The value of the photoinduced linear polarization had effect on diffraction properties in the holographic gratings. The grating strengths of two polarization are investigated and the relevant parameters for equal diffraction intensity readout are optimized.

• Journal of the Optical Society of Korea
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• v.7 no.4
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• pp.249-252
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• 2003

A simple multi-channel spectrum analyzer using an InGaAs array sensor and a diffraction grating is proposed and developed for high-capacity optical transport networks. With the developed multichannel spectrum analyzer, we could measure signal power, wavelength, and optical signal-to-noise ratio of each channel for multi-channel optical signals with 100 GHz and 50 GHz channel spacing, simultaneously. We could measure each channel power and wavelength with a deviation of less than 0.2 dB and 0.063 nm, respectively. We have obtained optical signal-to-noise ratio with a deviation of less than 1.0 dB compared with conventional optical spectrum analyzer in the wide input power range between -42 dBm and -27 dBm per channel.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.12
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• pp.71-79
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• 1994

In this paper, $As_{40}Se_{50-x}S_[x}Ge_{10}$(x=0, 25, 35, at.%) bulk and thin films, to develope device of reversible hologram, proved amorphous by X-RD analysis. On the thin films with composition rate, as Se-doped-quantity increased, absorption edge shifted to long wavelength, and we found that reversible photodarkening effect occurred when thin films are exposed and annealed. Optical energy gap was larger when thin films are annealed than exposed. In this effect thin films structurally stabilized by annealing. It is to formed grating hologram by the bragg method on the $As_{40}Se_{15}S_[35}Ge_{10}$ thisn films with the best transmittance properties As polariging angle grew larger, we found that maximum diffraction efficiency became smaller, and obtained it of 4.5% on the thin fim thicknesss of 0.6 m, polarizing angle of 40$^[\circ}$ and exposing for 20sec.

• Proceedings of the KIEE Conference
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• 2000.11c
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• pp.422-424
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• 2000

ZnO thin films for light emission device have been deposited on sapphire and silicon substrates by pulsed laser deposition technique(PLD). A Nd:YAG laser was used with the wavelength of 355 nm. In order to investigate the emission properties of ZnO thin films, PL measurements with an Ar ion laser as a light source using an excitation wavelength of 351 nm and a power of 100 mW are used. All spectra were taken at room temperature by using a grating spectrometer and a photomultiplier detector. ZnO exhibited PL bands centered around 390, 510 and 640 nm, labeled near ultra-violet (UV), green and orange bands. Structural properties of ZnO thin films are analized with X-ray diffraction (XRD).

• Journal of the Korean Society for Nondestructive Testing
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• v.12 no.1
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• pp.16-24
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• 1992

Moire interferometry using a diffraction grating and a laser is a powerful technique for analizing small deformation of a specimen. In the method, the x and y-directional fringe patterns are obtained by using the x and y-directional sets of two beams. If the both sets of two beams are simultaneously incident to the specimen, the x and y-directional fringe patterns are super imposed. In this case, it is difficult to separate each directional fringe pattern. Therefore each fringe pattern has been separately recorded by selecting each set of two beams. In order to analyze a two-dimensional strain changing with time, Moire interferometry using the two-dimensional fourier transform method is proposed and the x and y-directional fringes are separated. By this method, the thermal deformation of a glass plate is analyzed.

• International Journal of Precision Engineering and Manufacturing
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• v.9 no.3
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• pp.40-45
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• 2008

This paper presents a linear positioning system and its control algorithm design with nano accuracy/resolution. The basic linear stage structure is driven by an ultrasonic motor and its displacement feedback is detected by a LDGI (Laser Diffraction Grating Interferometer), which can achieve nanometer resolution. Due to the friction driving property of the ultrasonic motor, the driving situation differs in various ranges along the travel. Experiments have been carried out in order to observe and realize the phenomena of the three main driving modes: AC mode (for mm motion), Gate mode (for ${\mu}m$ motion), and DC mode (for nm motion). A proposed FCMAC (Fuzzy Cerebella Model Articulation Controller) control algorithm is implemented for manipulating and predicting the velocity variation during the motion of each mode respectively. The PCbased integral positioning system is built up with a NI DAQ Device by a BCB (Borland $C^{++}$ Builder) program to accomplish the purpose of an intelligent nanopositioning control.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.230-233
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• 2003

New photopolymers were designed and prepared using the photosensitive polymer binders. The photochemical reaction of the photosensitive polymer binder was studied by virtue of UV absorption and infrared spectroscopy. The holographic gratings were successfully fabricated in these photopolymer film samples by conventional optical interference method. We also investigated the effect of photocrosslink in the polymer binder on the diffraction behavior of the photopolymer. The dynamic behaviors of the grating formation were studied with the change of exposure intensity in terms of the diffraction efficiency. Particularly, we focused our efforts to observe the variation of the diffraction efficiency during post UV curing process.

• Korean Journal of Optics and Photonics
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• v.10 no.6
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• pp.494-499
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• 1999

We report on the results of holographic transmission grating that can be controlled by the applied AC electric field. We have fabricated a polymer-dispersed liquid crystal material that composed of multifunctional acrylate monomer blended with the liquid crystal mixture E7. To investigate an electro-optic properties of fabricated HPDLC, diffraction efficienties (DE) are measured as a fuction of applied electric field and density of liquid crystal. Maximum DE of about 70% is obtained about 30 wt% of LC concentration at a zero field. We have also shown that optical image was recorded in the tllm, and then the reconstructive image was switchable with the applied electric fields. ields.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.2
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• pp.25-28
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• 2010

The micro fabrication on the mold material using picosecond laser ablation processing has been studied. We used the two kind of system with picosecond laser. First one is two mirror type scanner and telecentric f-theta lens. Second one is X-Y stage and objective lens. By using these system, the $100{\mu}m$ size chess patterning and $2{\mu}m$ size patterning was fabricated. Especially $2{\mu}m$ size patterning on the mold material can be used as the decorative rainbow color logo for industrial field. In this paper, it is proved the picosecond laser is effective tool for the laser ablation processing.

• Transactions of the Society of Information Storage Systems
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• v.7 no.1
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• pp.31-35
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• 2011

In microholographic data storage system (MDSS), compact recording is required to achieve high capacity.[1] When the data is recorded, neighbor monomer is also affected by reaction at the focal point.[2,3] This unintended process caused more monomer consumption and degradation of total capacity. To avoid this extra consumption of dynamic range, it is required to define the effective dynamic range for MDSS. In this paper, we experimentally investigate the relation between dynamic range consumption and micro grating formation. Dynamic range consumption was monitored by real time read-out system. Micrograting was recorded with different consumption ratio and compared by diffraction efficiency of track direction. Finally, we define suitable dynamic range for MDSS.