• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1357-1360
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• 2009

In this study, the 0-th order diffraction could be efficiently removed with the obtained data for one hologram using the numerical reconstruction method. This method has a reduced data acquisition and processing time compared with the existing method wherein the data for two or more phase holograms are obtained for regeneration, and efficiently eliminates the 0-th order diffraction.

• Korean Journal of Optics and Photonics
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• v.15 no.1
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• pp.39-45
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• 2004

A computer simulation about removal of the 0-th order diffraction is achieved by using numerical reconstruction in digital holography and the Fourier transform method. A light intensity distribution hologram is generated through numerical calculation of the interference pattern. Additionally a phase hologram without the 0-th order diffraction is generated. The removal function for elimination of the 0-the order diffraction is introduced and the numerical reconstructions with several conditions for the removal of the 0-th order diffraction and the production of high quality numerically reconstructed images are tested and compared. The removal function is proven to be more effective at the suppression of the 0-th order diffraction compared with the DC suppression method.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.2
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• pp.155-160
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• 2024

The polarization-selective beam splitter grating can be widely used in numerous optical information processing systems. In this paper, to design a high-efficiency plasma polarization beam splitter (PBS), the structure composed of an Ag metal layer in Littrow mounting is implemented. To achieve high diffraction efficiency in the transmitted 0th-order TE polarization and the reflected 0th-order TM polarization, the grating depth and grating ratio of presented PBS is optimized by using rigorous Modal Transmission-Line Theory. From the optimized results, PBS has advantages of wide band properties for incident wavelength and angle, and the efficiency is higher than 95% for both TE and TM polarization. Therefore, this highly efficient PBS wideband grating with high extinction ratio can be used as an excellent optical diffraction device.

• Current Optics and Photonics
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• v.2 no.2
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• pp.125-133
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• 2018

We report an in-depth analysis of the design and fabrication of multilayer dielectric (MLD) diffraction gratings for spectral beam combining at a wavelength of 1055 nm. The design involves a near-Littrow grating and a modal analysis for high diffraction efficiency. A range of wavelengths, grating periods, and angles of incidence were examined for the near-Littrow grating, for the $0^{th}$ and $-1^{st}$ diffraction orders only. A modal method was then used to investigate the effect of the duty cycle on the effective indices of the grating modes, and the depth of the grating was determined for only the $-1^{st}$-order diffraction. The design parameters of the grating and the matching layer thickness between grating and MLD reflector were refined for high diffraction efficiency, using the finite-difference time-domain (FDTD) method. A high reflector was deposited by electron-beam evaporation, and a grating structure was fabricated by photolithography and reactive-ion etching. The diffraction efficiency and laser-induced damage threshold of the fabricated MLD diffraction gratings were measured, and the diffraction efficiency was compared with the design's value.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.39-42
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• 2000

Cutrent technological development toward miniaturization requires smaller components. These components usually generate complex multi-DOF motions other than simple 1-DOF motlon. Therefore it is essential to develop measurement methodology for 6-DOF motions. In this paper, a new 6-DOF measurement system for milli-struchlre is presented. This methodology basically employs the Optical Beam Deflection Method (OBDM) with a diffraction grating. A laser beam is emitted toward the difliaction grating which could be attached on the surface of a milli-structue and the incident ray is dif'||'&'||'acted in several directions. Among these difliacted beams, $0^{th}$ and $\pm$ $1^{th}4" order difkicted rays are detected by 4 Quadrant Photodiodes. From coordinate values fram each detector, we can get information for 6-DOF motions with lineariration method, Required resolutions for milli-struchue measurement are suh-micrometer in translation and arcsec in rotation. Experimental results indicate that proposed system has possibility to satisfy this requirement.

• Journal of Sensor Science and Technology
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• v.26 no.1
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• pp.28-34
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• 2017

An NIR grism Si optical area sensor spectrometer with in-band reference wavelength is designed and fabricated. It is composed of a transmission type diffraction grating (spatial density 300 line/mm), a rectangular N-BK7 prism (apex angle 30 degree), NIR filter(cutoff wavelength 720 nm), an imaging convex lens(focal length 50 mm F1.8) and an IR modified DSLR camera (Canon EOS40D) of Si optical area sensor ($3,888{\times}2,592$ pixels, pixel size $5.710{\mu}m$). "In-band reference wavelength function" is implemented using non-dispersive 0th diffraction order optical beam. The NIR grism spectrometer is tested in a laboratory using a halogen lamp and a Neon lamp. And the spectrometer is used in an astronomy field for obtaining the planet Jupiter NIR spectrum. In-band reference wavelength i.e. un-deviation wavelength is 846 nm, an wavelength resolution is 0.3027 nm/pixel, an wavelength resolving power is 2,794 and an wavelength range is 650~1,000 nm.

• Journal of the Korean Ceramic Society
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• v.48 no.5
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• pp.471-478
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• 2011

Investigations of crystal structure and phase transition of $Pb(Zr_{0.52}Ti_{0.48})O_3$ ceramics doped with A-site substitution impurity (La, Nd) or B-site substitution impurity (Sb, Nb) at 2 mol% concentration were carried out. X-ray diffraction patterns of impurities doped $Pb(Zr_{0.52}Ti_{0.48})O_3$ ceramics have been measured at pressures up to ~5 GPa with diamond anvil cell and synchrotron radiation. The patterns were obtained at room temperature using methanol-ethanol mixture as pressure-transmitting media. In order to refine the crystal structure, Rietveld analysis has been performed. The structures of impurities doped $Pb(Zr_{0.52}Ti_{0.48})O_3$ ceramics are tetragonal in space group P4mm at ambient pressure and are transformed into a cubic phase in space group Pm$\bar{3}$m as the pressure increases. In this study, when A-site substitution donor $La^{3+}$ or $Nd^{3+}$ ion was added to $Pb(Zr_{0.52}Ti_{0.48})O_3$ ceramics, the phase transition phenomena showed up at the pressure of 2.5~4.6 GPa, but when B-site substitution donor $Nb^{5+}$ or $Sb^{5+}$ ion was added to it, the phase transition appeared at relatively lower pressure of 1.7~2.6 GPa.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.176-177
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• 2013

Surface plasmon polaritons (SPPs) have attracted the attention of scientists and engineers involved in a wide area of research, microscopy, diagnostics and sensing. SPPs are waves that propagate along the surface of a conductor, usually metals. These are essentially light waves that are trapped on the surface because of their interaction with the free electrons of conductor. In this interaction, the free electrons respond collectively by oscillating in resonance with the light wave. The resonant interaction between the surface charge oscillation and the electromagnetic field of the light constitutes the SPPs and gives rise to its unique properties. In this papers, we studied theoretical and experimental extraordinary transmittance (T) and reflectance (R) of 2 dimensional metal hole array (2D-MHA) on GaAs in consideration of the diffraction orders. The 2d-MHAs was fabricated using ultra-violet photolithography, electron-beam evaporation and standard lift-off process with pitches ranging from 1.8 to $3.2{\mu}m$ and diameter of half of pitch, and was deposited 5-nm thick layer of titanium (Ti) as an adhesion layer and 50-nm thick layer of gold (Au) on the semiinsulating GaAs substrate. We employed both the commercial software (CST Microwave Studio: Computer Simulation Technology GmbH, Darmstadt, Germany) based on a finite integration technique (FIT) and a rigorous coupled wave analysis (RCWA) to calculate transmittance and reflectance. The transmittance was measured at a normal incident, and the reflectance was measured at variable incident angle of range between $30^{\circ}{\sim}80^{\circ}$ with a Nicolet Fourier transmission infrared (FTIR) spectrometer with a KBr beam splitter and a MCT detector. For MHAs of pitch (P), the peaks ${\lambda}$ max in the normal incidence transmittance spectra can be indentified approximately from SP dispersion relation, that is frequency-dependent SP wave vector (ksp). Shown in Fig. 1 is the transmission of P=2.2 um sample at normal incidence. We attribute the observation to be a result of FTIR system may be able to collect the transmitted light with higher diffraction order than 0th order. This is confirmed by calculations: for the MHAs, diffraction efficiency in (0, 0) diffracted orders is lower than in the (${\pm}x$, ${\pm}y$) diffracted orders. To further investigate the result, we calculated the angular dependent transmission of P=2.2 um sample (Fig. 2). The incident angle varies from 30o to 70o with a 10o increment. We also found the splitting character on reflectance measurement. The splitting effect is considered a results of SPPs assisted diffraction process by oblique incidence.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.8
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• pp.739-746
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• 2005

When we design a binary phase holographic optical low-pass filter (HOLF), the phase difference is generally set to be $\pi$ to optimize the diffraction efficiency. However, the phase difference of real HOLF mostly deviate from $\pi$ by the error in the fabrication process. The deviation causes the (0,0)-th order diffracted beam to increase, which results In raising the diffraction efficiency. To study the effects of the phase error on the performance of HOLF, we calculated the MTF of HOLF for various phase differences. The results show that the phase error of 10 $\%$ makes little change in the filtering characteristics of HOLF. Considering the filtering by lens and CCD, the effects of the phase error becomes much smaller. To confirm it experimentally, we fabricated HOLFs for various phase differences. After installing it in a digital camera, we take picture of test targets and observe the Moire fringes and the resolution. The results agree with our prediction.

• Journal of the Korean Magnetics Society
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• v.5 no.1
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• pp.64-70
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• 1995

The authors have studied crystallographic and magrletic properties of $NdFe_{10.7}TiM_{0.3}(M=B,\;Ti)$ by X-ray diffraction, VSM magnetometer, and Mossbauer spectrometer. The Alloys were prepared by arc-melting under argon atmosphere. The $NdFe_{10.7}TiM_{0.3}$ has pure single phase, whereas the $NdFe_{10.7}Ti_{1.3}$ contains some $\alpha-Fe$, from powder X-ray diffractometry. The $NdFe_{10.7}TiM_{0.3}$ has the $ThMn_{12}$-type tetragonal structure with $a_{0}=8.587\;{\AA}\;and\;c_{0}=4.788\;{\AA}$. The Curie temperature ($T_c$) is $570{\pm}3\;K$ from $M\"{o}ssbauer$ spectroscopy performed at various temperatures ranging from 13 to 770 K. Each spectrum of below $T_c$ was fitted with five subspectra of Fe sites in the structure ($8i_{1},\;8i_{2},\;8j_{1},\;8j_{2}\;and\;8f$). The area fraction of the subspectra at room temperature are 16.4, 8.2, 14.8, 21.3 and 39.3 %, respectively. Magenetic hyperfine fields for the Fe sites decrease in the order, $H_{hf}(8i)>H_{hf}(8j)>H_{hf}(8f)$.