• Journal of the Optical Society of Korea
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• v.18 no.5
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• pp.472-476
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• 2014

The Joint Transform Correlator (JTC) has been the most suitable technique for real time optical pattern recognition and target tracking applications. This paper proposes a new application of the JTC system for an analysis of the blurring effect of the optical images caused by a defocused lens. We present the relation between the correlation peak, optical transfer function (OTF), and the amount of blurring caused by focusing error. Moreover, we show a possibility of calibrating the blurred image by simply measuring the correlation peak.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.10
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• pp.1370-1376
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• 2003

The investigation of liquid fuel film on the cylinder liner is an essential to understand the engine-out hydrocarbon emissions formation in SI engines. In this research, two-dimensional visualization was carried out to investigate the liquid fuel film on the quartz liner in the optical engine. For this, the optical engine with hydraulic system was designed based on the commercial SI engine. The visualization was based on the laser-induced fluorescence with total reflection technique. Using a quartz liner and a special lens, only the liquid fuel film on the liner was visualized. With using this technique, the distribution of the fuel film on the cylinder liner was measured for different engine conditions and injection timing in the optical engine.

• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1668-1672
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• 2013

We developed a standoff Raman detection system for explosive molecules (EMs). Our system was composed of reflective telescope with 310 mm diameter lens, 532 nm pulse laser, and Intensified Charge-Coupled Device (ICCD) camera. In order to remove huge background noise coming from ambient light, laser pulses with nanosecond time width were fired to target sample and ICCD was gated to open only during the time when the scattered Raman signal from the sample arrived at ICCD camera. We performed standoff experiments with military EMs by putting the detector at 10, 20 and 30 m away from the source. The standoff results were compared with the confocal Raman results. Based on our standoff experiments, we were able to observe the peaks in the range of 1200 and $1600cm^{-1}$, where vibrational modes of nitro groups were appeared. The wave numbers and shapes of these peaks may serve as good references in detecting and identifying various EMs.

• Korean Journal of Optics and Photonics
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• v.4 no.2
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• pp.157-161
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• 1993

An optical autofocus system for a DUV KrF excimer laser wafer stepper was developed by using the PSD (Position Sensitive Detector) as the position sensor. The laser beam was incident on the surface of wafer and the reflected beam was magnified optically by a lens. And the beam was directed onto the surface of PSD by a mirror system. The spatial resolution of the autofocus system was found to be $0.03{\mu}m$.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.149-154
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• 2004

In the semiconductor and the optical industry a new transport system which can replace the conventional sliding system is required. These systems are driven by magnetic field and conveyer belt. The magnetic field damages semiconductor and contact force scratches the optical lens. The ultrasonic wave driven system can solve these problem. In this paper, the relationship of transporting speed according to the change of flexural beam shape and the effect of transporting speed according to the change of weight and amplification voltage are verified. The vibration behavior of flexural beam in the ultrasonic transport system is experimented using Laser Scanning Vibrometer.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.782-787
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• 2002

In optical disk drives (ODD), the demands of high data density and high speed have been increasing rapidly to achieve high data capacity and data transfer rate. The short wavelength laser, High NA objective lens, and high track following performance are needed to raise data density and data rate. For high-performance actuator, the improvement of linearity and acceleration become more important. Also, 3-axis actuator for active tilt compensation is introduced to overcome the decrease in disk tilt tolerance which is induced by short wavelength laser. In this paper, a hybrid type 3-axis actuator is presented and a new yoke structure, which can reduce the interaction between yoke and moving magnet, is designed to keep the efficiency of magnetic circuit. Experimental results show the validity of the yoke in the hybrid type actuator.

• Proceedings of the KIEE Conference
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• 1992.07a
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• pp.437-440
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• 1992

We design a multi-element photo-detector to measure the size of particles using the diffracted light energy distribution. The light energy that is scattered by particles in the collimated laser beam is collected by the Fourier transform lens and directed to the multi-semicircular concentric annular detecters. The scattered profile measured by the photodetector is sampled by a 32 channel analog-to-digital converter. A nonnegative least squares analysis translates the light energy distribution into the corresponding unique particle size distribution.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.972-978
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• 1989

Proposed is improved compact self-mixing type semiconductor-laser range finder, which measures mode-hop time interval (MHI). Measurement error caused by the fluctuation of MHI is greatly reduced by averaging many contiguous MHI's. The main cause of measurement error 1.5% at ranges from 0.1m to 0.8m is attributed to the optical phase change of a returned light from a focusing lens. Accuracy improvement by stabilization of the returned light is suggested.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.12
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• pp.16-22
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• 1994

In this paper, transmitter and receiver modules for free space optical interconnection are implemented and characterized. In the transmitter module, bias circuitry which inject current into the direct modulated laser diode is fabricated and in the receiver module, p-i-n diode is integrated with an MMIC amplifying stage. Laser diode has a direct-modulated bandwidth of 2 GHz at 1.4 Ith bias while p-i-n diode and amplifying stage has a bandwidth of 1.3 GHz and 1.5 GHz, repectively. Optical interconnection has a bandwidth of 1.3 GHz and linearly transmit modulated voltage signal up to 1.5 Vp-p. Measured loss of optical interconnection is 5dB which is composed of optoelectronic conversion loss of 15 dB, electrical impedance mismatch loss of 6.7 dB in transmitter module and gain of 18 dB in receiver module. Seperation between transmitter and receiver can be extended up to 50 cm by using a lens.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.51-54
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• 2000

The traditional surface measuring method using confocal principle requires much time to measure an object surface since it is a scanning tool. In this paper, the upgraded confocal microscope is introduced. It is also a scanning tool but it requires 2D-scanning while the traditional one requires 3D-scanning. It means the time for measuring is considerably reduced. In addition, the measuring system is configured to increase the efficiency of beam. He-Ne laser whose frequency is 632.8nm is used for the laser source. An example of measuring result through the upgraded confocal microscope is showed.