• Journal of the Optical Society of Korea
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• 제13권1호
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• pp.80-85
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• 2009

An experimental study of energy absorption and x-ray emission from ultrashort laser pulse irradiation of in-situ produced solid clusters has been performed. Silver clusters produced by a 30 mJ, 300 ps laser pulse were irradiated up to an intensity of $3{\times}10^{17}\;W/cm^2$ by a 70 mJ, 45 fs compressed laser pulse from the same Ti:sapphire laser. Absorption of the laser light exceeding 70% was observed, resulting in an x-ray yield (>1 keV) of ${\sim}60{\mu}J$ pulse. This may constitute a much simpler means of intense x-ray generation using ultrashort laser pulses as compared to the irradiation of structured / pre-deposited cluster targets, and it offers higher x-ray conversion efficiency than that from gas clusters and planar solid targets.

• 한국광학회:학술대회논문집
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• 한국광학회 1991년도 제6회 파동 및 레이저 학술발표회 Prodeedings of 6th Conference on Waves and Lasers
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• pp.64-64
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• 1991

The interaction of high-intensity, focused, nanosecond laser light with matter results in the production of high-temperature plasma, which in turn emits an intense pulse of x rays. The x-ray spectrum consists of strong line components of several keV photon energy and broad continuum. Such an x-ray source provides many advantages over conventional ones for many applications. Pulse nature of the x-ray emission is well-suited for studying transient phenomena and for imaging living biological specimen. Recent experiments have also shown that the laser plasma x ray may be used for x ray lithography. These studies and other applications will be discussed in detail.

• 한국정보통신학회논문지
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• 제14권7호
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• pp.1687-1692
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• 2010

본 논문에서는 Blu-ray 디스크의 기록을 위한 Laser Diode의 온도특성을 고려한 기록품질의 개선방법에 대해 연구했다. 주변 온도변화에 따라 Blu-ray Laser Diode는 전류-전압 관계로부터 미분저항이 변화하게 되는데 이러한 미분저항이 저온에서 기록품질에 미치는 영향에 대해 분석하고 개선하는 방법을 제안한다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2009년도 추계학술대회
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• pp.503-505
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• 2009

본 논문에서는 Blu-ray 디스크의 기록을 위한 Laser Diode의 온도특성을 고려한 기록품질의 개선방법에 대해 연구했다. 주변 온도변화에 따라 Blu-ray Laser Diode는 전류-전압 관계로부터 미분저항이 변화하게 되는데 이러한 미분저항이 기록품질에 미치는 영향에 대해 분석하고 개선하는 방법을 제안한다.

• Journal of the Optical Society of Korea
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• 제13권1호
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• pp.60-64
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• 2009

We attempted the first measurement of the spectral width of the nickel-like molybdenum x-ray laser (${\lambda}\;=\;18.895\;nm$) by use of a high-resolution spectrometer in order to determine the strength of the magnetic field required for the generation of a circularly polarized x-ray laser. The spectral width was measured to be ${\Delta}{\lambda}\;=\;18\;m{\AA}$ under the substantial lasing condition. The magnetic field required for the generation of a circularly polarized x-ray laser was 40 T. The splitting of the x-ray laser line was clearly obtained under 15 T external magnetic field. The strength of the magnetic field estimated from the splitting of the x-ray laser line was large compared with the external magnetic field. It implies that there might be an alternative mechanism for enhancement of the magnetic field in the gain medium plasma.

• Journal of the Korean Physical Society
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• 제73권12호
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• pp.1834-1839
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• 2018

A tabletop ultrafast soft x-ray has been generated from the laser-produce plasma with a femtosecond pulsed Ti:Sapphire laser. The estimated total flux of Al $K{\alpha}$ is of $2.2{\times}10^9photons/sec$ in $4{\pi}$ radian and the parameters related to the optical performance were obtained. The tungsten/silicon multilayer, flat quartz and bent thallium acid phthalate (TLAP) crystal were used for monochromatization of soft x-ray to refine the aluminum $K{\alpha}$ radiation and compared the respective value of $E/{\Delta}E$. To estimate the size of the x-ray source beam generated by a fs laser, the approximation using the FWHM obtained from the x-ray beam scan near the focal point was discussed, and the size of the diameter was about $9.76{\mu}m$.

• 한국기계가공학회지
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• 제6권3호
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• pp.16-23
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• 2007

An experimental investigation with diode laser system was carried out to study the effect of surface heat treatment on the die materials(SM45C, SKD11, SK3). The surface heat treatment characteristics of the laser beam are evaluated using hardness tests, optical microscopy, X-ray diffraction and energy dispersive X-ray spectroscopy(EDS). Results indicated that the beam size, focal length, feed rates are changed surface hardened characteristics. SM45C is higher hardness than other materials and composed to martensite grain at hardened zone, whereas other materials(SKD11, SK3)are low hardness than expected and composed to austenite and allayed martensite at hardened zone. The intensive X-ray diffraction patterns of (110)-(200)-(211) is detected hardened surface and the hardened surface distributed plenty of carbon density than metal zone.

• Journal of the Optical Society of Korea
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• 제7권4호
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• pp.230-233
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• 2003

This study describes the conceptual design of a soft x-ray microscope system based on a laserbased source for biomedical application with high resolution (${\leq}$50nm). The laboratory scale soft x-ray microscope consists of high power laser plasma x-ray source and grazing incidence mirrors with high reflectivity. The laser plasma source used for developing this system employs Q-switched Nd-YAG pulsed laser. The laser beam is focused on a tantalum (Ta) target. The Wolter type I mirror was used as condenser optics for sample illumination and as objective mirror for focusing on a detector. The fabrication of the Wolter type I mirror was direct internal cutting using ultraprecision DTM. A hydrated biological specimen was put between the two silicon wafers, the center of which was $Si_3N_4$ windows of 100㎚ thickness. The main issues in the future development work are to make a stable, reliable and reproducible x-ray microscope system.

• 한국광학회지
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• 제3권1호
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• pp.67-72
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• 1992

7년전 두 개의 그룹에 의해 강한 증폭된 자발 방출이 200.angs. 영역에서 관찰된 이래, 증폭도의 증가와 작동 파장영역의 확장등에서 세계적으로 많은 X-선 레이저 연구가 이루어져 왔다. X-선 레이저의 개발은 살아있는 생체조직을 고분해능으로 관찰할 수 있는 X-선 현미경 기술, 세포의 3차원 상을 가능케 하는 X-선 홀로그래피 기술, 고밀도 플라즈마의 진단 등의 여러 분야에 응용될 것이다. 국내에서도 기초적인 X-선 레이저 개발에 대한 연구가 과학기술원과 포항공과대학에서 시작되고 있어 곧 고무적인 연구결과가 나올 것으로 기대된다.

• Journal of the Optical Society of Korea
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• 제14권2호
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• pp.146-151
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• 2010

A comprehensive real-time spectral phase interferometry for direct electric field reconstruction (SPIDER) apparatus for characterizing femtosecond laser pulses is demonstrated. The SPIDER provides the temporal profiles of femtosecond laser pulses, reconstructed at the speed of 3.5 Hz, with parameters of the spectral phase such as group delay dispersion and third-order dispersion. The apparatus is applied successfully to optimize the spectral dispersion of a kHz femtosecond Ti:Sapphire laser by adjusting a grating compressor in real time.