• Journal of Mechanical Science and Technology
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• v.17 no.1
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• pp.139-145
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• 2003

Diode laser sensor is conducted to measure the gas temperature in the liquid-gas 2-phase counter flow flame. C$\_$10/H/ sub 22/ and city gas were used as liquid fuel and gas fuel, respectively. Two vibrational overtones of H$_2$O were selected and measurements were carried out in the spray flame region stabilized the above gaseous premixed flame. The path-averaged temperature measurement using diode laser absorption method succeeded in the liquid fuel combustion environment regardless of droplets of wide range diameter. The path-averaged temperature measured in the post flame of liquid-gas 2-phase counter flow flame showed qualitative reliable results. The successful demonstration of time series temperature measurement in the liquid-gas 2-phase counter flow flame gave us motivation of trying to establish the effective control system in practical combustion system. These results demonstrated the ability of real-time feedback from combustor inside using the non-intrusive measurement as well as the possibility of application to practical combustion system. Failure case due to influence of spray flame was also discussed.

• Journal of the Korean Society of Combustion
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• v.9 no.3
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• pp.27-35
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• 2004

Diode laser absorption sensors are advantageous because they may provide fast, sensitive, absolute, and selective measurements of species concentration. These systems are very attractive for practical applications owing to its compactness, resonable cost, robustness, and ease of use. In addition, diode lasers are fiber-optic compatible and thus enable simultaneous measurements of multiple species along a line-of-sight. Recent advances of room-temperature, near-IR and visible diode laser sources for telecommunication, optical data storage applications make it possible to be applied for combustion diagnostics based on diode laser absorption spectroscopy. Therefore, combined with fiber-optics and high sensitive detection strategies, compact and portable sensor systems are now appearing for variety of applications. The objectives of this research are to develope a new gas sensing system and to verify feasibility of this system. Wavelength and power characteristics as a function of injection current and temperature are experimentally found out. Direct absorption spectroscopy has been demonstrated in these experiments and has a bright prospect to this diode laser system.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.158-161
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• 1995

A new laser diode range-finding speedometer is proposed, which is modulated by a pair of positive and negative triangular pulse current superimposed on a dc current. Since a target velocity is directly obtained form a pure Doppler beat frequency measured during the non-modulation period, the new sensor is free from the difficulties due to the critical velocity encountered in the previous sensor. Furthermore, the different amplitude of the two triangular pluses are so adjusted that the measurable range using only one laser head is greatly expanded to 10cm through 150cm, which is about two times that of the previous sensor. The measurement accuracy for velocity of .+-.6mm/s through .+-.20mm/s and for range is about 1%, and 2%, respectively. Because the new sensor can be operated automatically using a microcomputer, it will be useful for application of a 3-D range image measurement of a slowly moving object.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.222-227
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• 2003

Recent advances in room-temperature, visible and near-IR diode laser sources for telecommunication, optical data storage applications are enabling combustion diagnostics system based on diode laser absorption spectroscopy. In contrast to some traditional sampling-based gas-sensing instruments, tunable diode laser absorption spectroscopy system is advantageous because of their non-invasive nature, high sensitivity, fast response time and real-time measurement capability. So, combined with fiber-optics and high sensitive detection strategies, compact and portable sensor system arc now appearing for a variety of applications. The objective of this research is to take advantage of distributed feed-back diode laser and measure the $CO_{2}$ concentration (by using direct absorption and wavelength modulation spectroscopy methods). In addition to survey spectra of $CO_{2}$ bands and spectroscopic parameters between 1565 and 1579 run were computed at temperatures between 296 and 1200 K (by using HITRAN 2000 database). It experimentally found out that the features of direct absorption and wavelength modulation spectroscopy methods.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.579-581
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• 2006

Flat panel image display devices such as TFT LCD and PDP have required more large area and high quality control components. To control the qualities of the components, measurements of the flatness of a plate glass has been required. In order to measure the shape of the specular objects, Non-Contact Optical Sensor using Hologram laser unit was proposed. The sensor has a optical system that is composed of a Hologram laser and objective lens. The temperature of the sensor body is controlled by TEC(Thermoelectric Cooler) to maintain the same wavelength of the diode laser. In this research, we proposed the calibration scheme to make sensor real time measuring sensor. From the experimental results we see that the proposed sensor unit can measure the position of the glass surface in rial time.

• International Journal of Precision Engineering and Manufacturing
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• v.8 no.2
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• pp.80-84
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• 2007

We propose a new displacement measurement method using a phase modulation homodyne interferometer and a tunable laser diode as a light source to determine an arbitrary length with a resolution in the order of 10 pm. In the proposed instrument, the displacement of a movable mirror in the interferometer can be converted to a frequency shift of the tunable laser diode. We discuss the principles of the proposed method, the instrumentation, and the experimental results, and compare the proposed method with two commercial displacement sensors. The commercial sensors used are a heterodyne interferometer, the interpolation error of which is also measured, and a capacitive sensor.

• Journal of Sensor Science and Technology
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• v.17 no.3
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• pp.157-161
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• 2008

An optical sensor was developed to detect nanoparticles, turbid materials and microorganisms in water simultaneously. Three different light sources like UV-LED, NIR-LED and laser diode have been employed to develop the optical sensor based on the scattering light and fluorescence light. The sensor system has high selectivity and sensitivity, that it can be used to monitor the quality of drinking water.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.11
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• pp.1992-1994
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• 2007

In this paper we propose a cryogenic sensor system which can measure the temperature at higher resolution at low temperature using temperature-dependent amplified spontaneous emission of erbium-doped fiber pumped by a 1480 nm laser diode. The measurement resolution of the sensor system could be enhanced through the modulation of injection current of the pump laser diode. The measurement resolution considering the fluctuation of the light source in the sensor system was ${\sim}0.4$ K in the room temperature regime and ${\sim}0.07$ K in the liquid nitrogen temperature regime.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.383-384
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• 2007

• Journal of the Korean Society for Precision Engineering
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• v.20 no.10
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• pp.141-147
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• 2003

This paper represents an absolute positioning system using a light navigation path for mobile robot. The absolute positioning system is composed of the projector unit which generates a laser beam using laser diode and mobile robot with the optical detector which has some optical sensors. The projector unit is fixed over the navigating plane of mobile robot to generate the light navigation path, and the optical detector located upper part of mobile robot detects the generated laser beam from the projector. The navigation of mobile robot is controlled by the micro-processor which compares the detected present position from the detector with the previously programmed navigation path. And experimental results show that our sensor system can be used for the absolute positioning system of the mobile robot.