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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Korean Journal of Optics and Photonics
Journal Basic Information
Journal DOI :
Optical Society of Korea
Editor in Chief :
Volume & Issues
Volume 9, Issue 6 - Dec 1998
Volume 9, Issue 5 - Oct 1998
Volume 9, Issue 4 - Aug 1998
Volume 9, Issue 3 - Jun 1998
Volume 9, Issue 2 - Apr 1998
Volume 9, Issue 1 - Feb 1998
Selecting the target year
Design of relfectors for reflective LCDs
Korean Journal of Optics and Photonics, volume 9, issue 6, 1998, Pages 355~361
Reflectors for reflective LCDs are required to be able to control the direction of the image and viewing angle range for optimal display. To achieve these required characteristics, we performed elementary experiments on conventional reflectors, and theoretical analyzed the reflective property of rough surfaces by using scattering theory. We also proposed a reflector structure by which we can control the direction of the image and viewing angle characteristics simultaneously. If we fabricate and apply this reflector to the reflective LCDs, we can realize high performance display
Improvement of size measurement polystyrene spheres of diameters 3
m and 10
m by optical microscope with CCD camera
Korean Journal of Optics and Photonics, volume 9, issue 6, 1998, Pages 362~367
Center Distance Finding (CDF) is a technique to find the sphere diameter by measuring the distance between two contacting spheres. The focal spots of the sphere clusters are formed in the back-focal plane by the transmission-mode optical microscope with the pseudothermal illumination source. Digital images taken by the CCD camera were processed by the software called Global Lab Image. The centers of the focal spots are found and the spot positions are expressed in terms of the CCD pixel elements, whose coordinate are calibrated by a heterodyne interferometer. The new CDF measurement system has been developed, which are more advantageous in time and convenience than the existing system, while the measurement uncertainly remains sufficient for its use as a magnification standard for optical microscopy. Two kinds of polystyrene spheres whose nominal diameters 3 and 10
(NIST SRM 1962 and 1960) are measured with the uncertainly less than 1% at the confidence level of 99%, and the results are compared with the results of National Institute of Standards and Technology.
Designing a kmultiview 3D display system based on a spatiotemporal multiplexing
Korean Journal of Optics and Photonics, volume 9, issue 6, 1998, Pages 368~372
A 16-views 3 dimensional imaging system is designed by spatially combinding two 8-views time multiplexed image channels. Each 8-views channel composed of 3 primary color CRTs and a dichroic beam splitter which combining the three CRTs as one channel. Each CRT displays 8-view images time sequentially. These images are projected to a holographic screen of a size 1
through a projection optics. Characteristics of the three different configurations of projection optics are examined with the optics designing program "DEMOS" to select an optimized projection optics for the system. The configulation of the optimized projection optics is found like following; images from each channel combined by two-fold mirror are projected by a projection objective through a 16-strips LCD shutter. In this configuration, the shutter should be located at the entrance pupil of the objective, and the folded edge of the two-fold mirror should contact symmetrically to the center line of the shutter.e shutter.
Color reproduction using color appearance model in LCD projection systems
Korean Journal of Optics and Photonics, volume 9, issue 6, 1998, Pages 373~379
A new method is proposed for the design of the dichroic mirrors in 3-LCD projection systems for color separation/composition. Rather than simply basing the color performance cirterion on luminance or chromatic saturation only, the optimum design parameters can be found by maximizing the volume of the perceived color gamut in RLAB color space and related color appearance model and used the linearly approximated spectrum of dichroic mirrors for simplicity and vector space description. By this method, we found optimal half-power wavelengths in dichroic mirrors which maximized our performance criterion.
Thermal diffusivity measurement of two-layer ar-coating systems using photoacoustic effects
Korean Journal of Optics and Photonics, volume 9, issue 6, 1998, Pages 380~384
As the development of ultrahigh power laser system, the laser mirrors must require high-resistant and effectively cooled. So, the study for the optical multilayer systems having large thermal diffusivity become important. In this study, we designed and fabricated two-layer anti-reflection (AR) optical coating samples, in different evaporation conditions of coating speeds (10, 20
/s) and substrate temperatures (50, 100, 150, 20
), using two dielectric materials
and ZnS which have different refractive indices and measured the through-plane thermal diffusivity by using photoacoustic effect. The optical thicknesses of
and ZnS layer were fixed as 5/4λ (λ=514.5nm) and λ, respectively, and the thermal diffusivity of the samples fabricated in the different conditions was obtained from the measured amplitude of photoacoustic signals by changing chopping frequency of
layer beam. The results told us that the thermal diffusivity of the sample fabricated in the condition of 10
/s and 15
showed the largest value.
Volume holographic correlator for fingerprint recognition
Korean Journal of Optics and Photonics, volume 9, issue 6, 1998, Pages 385~389
In this paper, we propose an optical correlator system using volume holograms for database of matched filters. Optical correlator has high speed and parallel processing characteristics of optics. Matched filters are recorded into a volume hologram that can store data with high density, transfer them with high speed, and select a randomly chosen data element. The multiple reference images of database are prerecorded in a photorefractive crystal in the form of Fourier transform images, simply by passing the image displayed in a spatial light modulator through a Fourier transform lens. The angular multiplexing method for multiple holograms of database can be achieved by rotating the crystal by use of a step motor. Experimental results show that the proposed system can be used for the fingerprint recognition.
Improvement of iterative fourier transform algorithm
Korean Journal of Optics and Photonics, volume 9, issue 6, 1998, Pages 390~395
Iterative Fourier transform algorithm (IFTA) was utilized for the phase retrieval problem or the optimal of the IFTA depends strongly on the selection of initial phase value. In this paper, we proposed the modified interactive Fourier transform algorithm in order to improve the convergence speed of error and the stability of convergence. The modified IFTA was reduced number of iteration about 30% than existing IFTA with the image size of 128
Numerical calculation of contrast transfer function for periodic line-space patterns
Korean Journal of Optics and Photonics, volume 9, issue 6, 1998, Pages 396~402
The measurement of OTF(optical transfer function) is used for evalution of imaging performance of optical system as a standard method. In the mass-production, the contrast measurement of projected patterns is also popular because of its simplicity. In this study, a computer program which evaluates the CTF(contrast transfer function) of optical system for periodic line-space patterns is developed by using the diffraction imaging theory. The MTF(modulation transfer function) and CTF of an aberrated system are evaluated and analyzed for the third order aberrations expressed by the C-coefficients and the Zemike polynomials.
Polarization properties and single-mode operation of an internal-mirror 543 nm He-Ne laser
Korean Journal of Optics and Photonics, volume 9, issue 6, 1998, Pages 403~407
The polarizatin properties of an internal-mirror 543 nm He-Ne laser with and without a transverse magnetic field were investigated for single-mode operation. Two orthogonal eigenpolarizations field to the natural tube axes of laser were observed when the emitted laser output was linearly polarized. Polarization unstability between these polarizations occurred when the applying a 500 gauss transverse magnetic field at 35
with respect to the natural tube axes of laser. Under such conditions stable single-mode operation which is useful for the frequency stabilization of a 543 He-Ne laser to
-saturated absorptions was obtained in the tuning range of 880 MHz.
Improved method of lateral offset calculation for optical waveguide
Korean Journal of Optics and Photonics, volume 9, issue 6, 1998, Pages 408~412
As the radius of curvature of curved optical waveguide gets smaller, the loss increases at the junction of linear-curved waveguide by the cross sectional mode mismatch. The concept of lateral offset has been used widely to minimize it, and simple method of maximum matching has been efficient for most cases of silica waveguide with low optical confinement and large radius of curvature. Here, we analyzed that the propagation mode characteristics of the lateral offset and propagation mode characteristics of general case with effective index method and Airy function solution. As the normalized frequency varies, mode characteristics changes near the boundary of 1/V=0.7 and the simple matching of gaussian profile might give -35% of error at most. We proposed improved method with a new correction factor to improve the mode mismatch problem of conventional methods for general cases, and showed the convenience and feasibility of this method for the calculation of the lateral offset.
Gain flattening of erbium-doped fiber amplifiers by using an AOTF for long-haul WDM optical transmissions
Korean Journal of Optics and Photonics, volume 9, issue 6, 1998, Pages 413~416
We have flattened the gain of EDFA by using a long-period FBG filter and AOTF's. The gain and optical SNR characteristics of the gain-flattened EDFA in long-haul transmission been evaluated in a recirculating EDFA loop. The gain variation was less than 4.6 dB and the optical SNR was higher than 14 dB over 20-nm wavelength range when the optical signal went through the EDFA as many as 200 times. These results indicate that this gain-flattened EDFA is applicable for ultra long-haul WDM optical transmissions over 8000 km.
Optimization of panel parameters and drive signals for high-speed matrix addressing of a bistable twisted-nematic LCD
Korean Journal of Optics and Photonics, volume 9, issue 6, 1998, Pages 417~422
In this paper we introduce a method to optimize panel parameters and drive signals in a matrix-adressed bistable twsited-nematic (BTN) liquid crystal display (LCD) panel. We measured the effect of data pulses on optical switching characteristics in a BTN LC cell to model the effect theoretically. We introduce a weighting function to model the effect of data pulses on the switching energy as a function of time. Once the weighting function is known, we can estimate the maximum number of lines for multiplexing operation at a given frame rate by calculating the minimum data pulse width. By characterizing a unit cell as we change panel parameters (for example, d/p ratio), we can optimize parameters for high-speed operation. We found that our theoretical predictions agree very well with experimental results.
Two-wave mixing in Ce:
Korean Journal of Optics and Photonics, volume 9, issue 6, 1998, Pages 423~427
Two wave mixing experiments in
are carried out, and the characteristics as optical information processing device are investigated. Examined crystals are commonly used ones, such as 0.03% mol Ce-doped
, 0.03% mol Fe-doped
, and 6% mol MgO-doped
. $Ar^+$ ion laser is used as the writing beam, and He-Ne Laser is used as the reading beam. The recording-decay and erasing characteristics of diffraction gratings, the time constants, and also the angular selectivities are measured for each crystals and compared.
Array of GaAs/AlGaAs quantum well infrared photodetector with 7.8
Korean Journal of Optics and Photonics, volume 9, issue 6, 1998, Pages 428~432
We fabricated 1
8 array of GaAs/AlGaAs quantum well infrared photodetectors for the long wavelength infrared detection which is based on the bound-continuum intersubband transition, and characterized its electrical and optical properties. The device was grown on SI-GaAs(100) by the molecular beam epitaxy and consisted of 25 period of 40
GaAs well and 500
As barrier. To reduce the possibility of interface states only the center 20
of the well was doped with Si (
). We etched the sample to make square mesas of 200
and made an ohmic contact on each pixel with Au/Ge. Current-voltage characteristics and photoresponse spectrum of each detector reveal that the array was highly uniform and stable. The spectral responsivity and the detectivity
were measured to be 180,260 V/W and
respectively at the peak wavelength of
and at T=10 K.