• Korean Journal of Optics and Photonics
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• v.22 no.5
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• pp.239-244
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• 2011

We introduce Gaussian (or paraxial) optics that can be successfully applied to design, for use in a color analyzer, a non-imaging optical system on a measurement probe for LCD display. The color analyzer is used to decompose colored lights leaving from some measurement area on the LCD display to red, green, and blue. The color analyzer must include a condenser lens whose purpose is to gather colored lights to illuminate a small area on the sensor. In order to satisfy a reduction ratio between the measurement area and the sensing area with a non-imaging condition, a condenser lens is analytically treated by means of Gaussian optics so that good understanding of the non-imaging condenser lens is achieved as a good design is derived. As a result, the technique shows the necessity of analytical treatment in contrast to the design approach using only commercial software such as CODE-V, Light-Tools, and others. Of course, CODE V and Light-Tools are also utilized in this paper to confirm and complete the Gaussian optical design.

• Current Optics and Photonics
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• v.4 no.3
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• pp.229-237
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• 2020

In this study, a beam-coupling system is designed to improve the coupling efficiency of achip-integrated spectrometer when the waveguide is arranged in a linear and discrete manner. In the proposed system the beam is shaped to be anti-Gaussian, to deposit adequate energy in the edge waveguides. The beam is discretely coupled to the corresponding waveguide by a microlens array, to improve the coupling efficiency, and is compressed by a toroidal lens to match the linear discrete waveguides. Based on the findings of this study, the coupling efficiency of the spectrometer is shown to increase by a factor of 2.57. Accordingly, this study provides a reference basis for the improvement of the coupling efficiency of other similar spectrometers.

• Korean Journal of Optics and Photonics
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• v.10 no.6
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• pp.448-452
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• 1999

The Gaussian impulse fUllction initially assumed in the inverse problem is $e^{-\sigma^2\chi^2}$. The modified Gaussian amplitude pupil function $e^{\frac-{\omega^2}{4\sigma^2}$ is obtained by the inverse Fourier transform of $e^{-\sigma^2\chi^2}$. A Gaussian amplitude modulation plate (GAMP) is designed and fabricated by using absorption and transparence glass which are the same refractive index. It is compared the experimental transmittance with theoretical that of GAMP. It is found that the linewidth of Gaussian optical imaging system obtained by wavelength is $0.365{\mu}m$ and NA is 0.07 is decrease 2/3 than that of Rayleigh.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.5
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• pp.148-156
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• 1996

Automatic product system is gradually increasing according to development of industrial society. On-line measurement makes a important role in view of economic and effective side in industrial product system. Syncronization system is developed to measure screw thread which is rotating. In-process measuring of rotating body have a lot of difficuties even thoufht using various method containing high speed camera. So, now we suggest one of the new method which is not so expansive. In this study, digital value was produced through the image processing algorithm from acquired orignal image. As a result, we have a good agreement between measuring values calculated from image conture and measuring values acquired from profile project by means of experiment, respectively.

• Korean Journal of Optics and Photonics
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• v.17 no.3
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• pp.216-222
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• 2006

We propose the use of the Gaussian-curve fitting algorithm for the improvement of measurement accuracy in wavelengthscanned Fabry-Perot filter based demodulation systems. The peak locations of FBG sensors were calculated from the fitted curves rather than from distorted PD profiles, resulting in much better measurement accuracy than that of the highest-peak search algorithm. Also, the algorithm was proved to minimize measurement uncertainty of spectrally-distorted grating sensors. From our experimental results, a temperature resolution as small as ${\sim}0.3^{\circ}C$ was readily achieved by use of the Gaussian-curve fitting algorithm whereas the highest-peak search algorithm gave a temperature resolution larger than ${\sim}4^{\circ}C$.

• Current Optics and Photonics
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• v.3 no.5
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• pp.466-472
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• 2019

A system for continuous-wave coherent Doppler lidar (CW lidar), made up of all-fiber structures and a coaxial transmission telescope, was set up for wind measurement in Hefei (31.84 N, 117.27 E), Anhui province of China. The lidar uses a fiber laser as a light source at a wavelength of $1.55{\mu}m$, and focuses the laser beam on a location 80 m away from the telescope. Using the CW lidar, radial wind measurement was carried out. Subsequently, the spectra of the atmospheric backscattered signal were analyzed. We tested the noise and obtained the lower limit of wind velocity as 0.721 m/s, through the Rayleigh criterion. According to the number of Doppler peaks in the radial wind spectrum, a classification retrieval algorithm (CRA) combining a Gaussian fitting algorithm and a spectral centroid algorithm is designed to estimate wind velocity. Compared to calibrated pulsed coherent wind lidar, the correlation coefficient for the wind velocity is 0.979, with a standard deviation of 0.103 m/s. The results show that CW lidar offers satisfactory performance and the potential for application in wind measurement.

• Journal of electromagnetic engineering and science
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• v.15 no.4
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• pp.206-212
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• 2015

This paper introduces new wideband antenna-filter-antenna (AFA) uniform arrays that can be utilized as frequency selective surfaces (FSS) with low loss and sharp roll-off response, which are highly desirable characteristics for millimeter wave applications. The design adopts a simple 3-layer single polarization structure consisting of two patch antennas and a resonator. Both simulations and measurements are used to characterize the performances of the proposed design. Overall results show 18.5% 10-dB bandwidth. For the targeted band the insertion loss is less than 0.2 dB. Possible applications include quasi-optical amps, grid mixers and radomes for aircraft radar antennas.

• Korean Journal of Optics and Photonics
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• v.10 no.6
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• pp.500-506
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• 1999

We designed and fabricated a bidirectional optical transceiver module for low cost access network. An integrated chip forming a pin-PD on an 1.3 urn FP-LD was assembled by flip-chip bonding on a Si optical bench, a single mode fiber with an angled end facet was aligned passively with the integrated chip on V-groove of Si-optical bench. Gaussian beam theory was applied to evaluate the coupling coefficients as a function of some parameters such as alignment distance, angle of fiber end facet, vertical alignment error. The theory is also used to search the bottle-neck between transmittance and receiving coupling efficiency in the bi-directional optical system. Tn this paper, we confirmed that reduction of coupling efficiency by the vertical alignment error between laser beam and fiber core axis can be compensated by controlling the fiber facet angle. In the fabrication of sub-module, a'||'&'||' we made such that the fiber facet have a corn shape with an angled facet only core part, the reflection of transmitted laser beam from the fiber facet could be minimized below -35 dE in alignment distance of 2: 30 /J.m. In the same condition, transmitted output power of -12.1 dEm and responsivity of 0.2. AIW were obtained.