• Journal of IKEEE
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• v.14 no.3
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• pp.244-249
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• 2010

We fabricated optical sensor system that take a measurement particles using a line-CCD in ocean. To measure particles, we used 680nm laser diode which is appropriate. we tested to operate optical system in water tank and ocean. It has performance that detected signal of sensors transfer microprocessor, FPGA as long as move up and down it's motion. The system algorithm also analysis output -pressure, temperature, particle numbers in depth.-For experiment, our particle sensor system has high accuracy counter. therefore, we proposed that a line-CCD is available on optical sensor system in ocean.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.38 no.4
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• pp.33-38
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• 2001

Readout signal of high density DVD-RAM disk output was simulated to analyze the effect of crosserase and crosstalk to the readout signal which is one of the main difficulties to realize high density DVD-RAM system having single side recording density of 4.7 G13 and 15 G13 media. Laser beam intensity impinged on the disk was approximated as Gaussian and recorded marks were assumed elliptical and the readout signal was calculated as a two dimensional convolution of laser beam pattern and recored mark pattern. From the readout signal obtained by varying crosserase ratio, carrier levels with period of 3T to 11 T were calculated and compared. Jitter due to crosserase and crosstalk was calculated and compared using 1,000 random marks having 3T to 11T period. The results showed that the jitter due to crosserase turned out to be smaller than the jitter due to crosstalk.

• Korean Journal of Optics and Photonics
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• v.18 no.4
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• pp.280-285
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• 2007

Based on the multimode fiber taper, a mode size converter for effective optical beam coupling between laser and optical fiber or between the two different optical fibers has been proposed and demonstrated. The device has a multimode input end and a single mode output end. The influence of various parameters, including device structure and launching conditions, on the coupling efficiency has been theoretically analyzed. The theoretical results revealed that the gaussian beam can be coupled into a single mode fiber without considerable insertion loss. The proposed multimode fiber taper has been fabricated using heating and pulling equipment incorporating two micro-torches. Experimental results showed that an optical beam with $50\;{\mu}m$ of large beam size was effectively coupled into single mode fiber through the multimode fiber taper. The insertion loss of the device was 1.3 dB.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.4A
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• pp.408-416
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• 2010

A dumbbell-type CPW transmission-line structure has been proposed to improve the return loss of the transmission line between a driver IC and flip-chip-bonding VCSEL(Vertical Cavity Surface Emitting Laser) in a hybrid opto-electric circuit board(OECB). The proposed structure used a pair of dummy ground solder balls on the ground lines for flip-chip bonding of the VCSEL and designed the dumbbell-type CPW transmission line to improve reflection characteristics. The simulated results revealed that the return loss of the dumbbell-type CPW transmission line was 13-dB lower than the conventional CPW transmission line. A 4-dB improvement in the return loss was obtained using the dummy ground solder balls on the ground lines. The variation rate of the reflection characteristic with the variation of terminal impedances of the transmission line (at the output terminal of the driver IC and the input terminal of the VCSEL) is about ${\pm}2.5\;dB$.

• Korean Journal of Optics and Photonics
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• v.13 no.6
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• pp.548-553
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• 2002

We have investigated the output characteristics of a Nd:YAG oscillator with a Stimulated Brillouin Scattering phase conjugation mirror (SBS-PCM). FC-75 is used as an SBS gain medium and Cr:YAG (T=50%) as a Q-switcher. The SBS-PCM consists of an SBS-cell and a simple plano-convex focusing lens system. For the case of not using a Q-switcher, an SBS-cell doesn't work as a phase conjugation mirror. For the case of using a Q-switcher, the energy characteristics remains nearly the same whether using the SBS-cell or not using it. The pulse width is reduced from 50 ns to 40 ns by an SBS-PCM. When the SBS-cell is used with a Q- switcher, the SBS-cell works very well as a phase conjugation mirror and its beam-profile is improved dramatically. And in order to explain the progression of beam-profile, we propose a simple model based on the nonlinear reflectivity of the SBS-PCM, whose reflectivity is dependent on the pumping intensity at the focal plane.

• Korean Journal of Optics and Photonics
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• v.22 no.2
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• pp.102-107
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• 2011

In this paper, a small double ring resonator reflector was designed and fabricated using a polymer waveguide, and the measurement result was discussed. A widely tunable characteristic of the small double ring resonator caused by the Vernier effect, which results from the difference of the ring radii, was observed. The insertion loss of the double ring reflector was reduced by minimizing the device length to be as short as possible, and thus the output power and the SMSR (side mode suppression ratio) was greatly enhanced. The hybrid integrated laser based on the small double ring resonator reflector lased with the SMSR of 45 dB. In addition, the wide tuning range of 40 nm could be obtained by injecting a current of 30 mA to an electrode on top of the reflector.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.5
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• pp.555-560
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• 2014

In order to improve spectrum sensitivity of photodiode for detection of the laser wavelength at 850 nm ~ 1000 nm of near-infrared band, this study has produced silicon-based photodiode whose area is $5000{\mu}m{\times}2000{\mu}m$, and the thickness is $280{\mu}m$. It was packed by the TO-5 type. The electrical properties of the dark currents have valued of approximately 0.1 nA for 5 V reverse bias, while the capacitance showed 32.5 pF at frequency range of 1 kHz and about 32.4 pF at the range of 200 kHz for 0 V. In addition, the rising time of output signal was as fast response as 20.92 ns for 10V. For the optical properties, the best spectrum sensitivity was 0.57 A/W for 890 nm, while it was relatively excellent value of 0.37 A/W for 1,000 nm. Over all, there were good spectrum sensitivity for this diode over the range of 870 ~ 920 nm.

• Journal of Navigation and Port Research
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• v.26 no.2
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• pp.235-243
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• 2002

Theoretical analysis have been performed to design the high power semiconductor laser for an optical sensor at 1.55${\mu}{\textrm}{m}$ wavelength range which is the lowest loss wavelength in optical fiber. The materials of active region and SCH were $Ln_{1-x}Ga_xAs_yP_{1-y}$. In order to use the light source of optical sensors, it has to satisfy wide spectral width and short coherence length. Therefore, in order to suppress lasing oscillation, we proposed laterally tilted PBH type with a window region. Also, tapered stripe structure was applied for high coupling efficiency into a single mode fiber. From these analyses, the devices of laterally tilted angled and bending structure were fabricated and their characteristics were measured. In the results of the measurement, the fabricated devices have sufficient output power and wide FWHM to apply to the light source of optical fiber sensors.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.134-138
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• 2021

Various types of precision plastic thin films are used widely in high-performance displays, such as smartphones. For plastic thin-films manufactured by the Roll-to-Roll process, the film thickness must be measured and managed while moving. In the Roll-to-Roll process, wrinkles are generated when tension is applied to the film, which causes an inclination on the optical axis of the thickness gauge, resulting in a loss of accuracy. Therefore, this study attempted to develop an optical interference tomography measurement system. In this study, the tilt angle of the film was measured to correct the measurement value error in the thickness gauge caused by the tilt of the film. The system was constructed so that the laser was irradiated on the tilted film, and the laser reflected from the film was formed on the PSD. The relationship between the tilt angle of the film and the output value of the PSD was obtained experimentally. Using this, a device to measure the tilt angle of the film was constructed, and angle measurements were taken at a speed of 250,000Hz.

• Journal of ILASS-Korea
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• v.28 no.1
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• pp.1-9
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• 2023

In the cylinder of gasoline direct injection engines, the spray targeting from injectors is of great significance for fuel consumption and pollutant emissions. The automotive industry is putting a lot of effort into improving injector targeting accuracy. To improve the targeting accuracy of injectors, it is necessary to develop models that can predict the spray targeting positions. When developing spray targeting models, the most used technique is computational fluid dynamics (CFD). Recently, due to the superiority of machine learning in prediction accuracy, the application of machine learning in this field is also receiving constant attention. The purpose of this study is to build a machine learning model that can accurately predict spray targeting based on the design parameters of injectors. To achieve this goal, this study firstly used laser sheet beam visualization equipment to obtain many spray cross-sectional images of injectors with different parameters at different injection pressures and measurement planes. The spray images were processed by MATLAB code to get the targeting coordinates of sprays. A total of four models were used for the prediction of spray targeting coordinates, namely ANN, LSTM, Conv1D and Conv1D & LSTM. Features fed into the machine learning model include injector design parameters, injection conditions, and measurement planes. Labels to be output from the model are spray targeting coordinates. In addition, the spray data of 7 injectors were used for model training, and the spray data of the remaining one injector were used for model performance verification. Finally, the prediction performance of the model was evaluated by R² and RMSE. It is found that the Conv1D&LSTM model has the highest accuracy in predicting the spray targeting coordinates, which can reach 98%. In addition, the prediction bias of the model becomes larger as the distance from the injector tip increases.