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어븀:이터븀:유리 마이크로칩 레이저를 이용한 단펄스 거리측정기 설계
고해석,이창재,박충범,전형하,안필동,박도현,Koh, Hae Seog,Lee, Chang Jae,Park, Choong Bum,Jeon, Hyoung Ha,Ahn, Pil Dong,Park, Do Hyun 한국군사과학기술학회 2018 한국군사과학기술학회지 Vol.21 No.3
We present a passively Q-switched monolithic Er:Yb:glass microchip laser developed in our lab. The microchip laser can produce pulses at 1535 nm of the 'eye-safe' wavelengths with the pulse energy of 50 uJ and the pulse width of 4-6 ns. Using the laser we also designed and developed a pulsed Er:Yb:glass microchip laser rangefinder. Expressions for background and signal power, noise, and signal-to-noise ratio are reviewed. A computer simulation was used to optimize laser power, receiver aperture, and preamplifier bandwidth for the efficient system design of the laser rangefinder. Experimental results are presented to compare with the theory.
줌렌즈 광속확대기를 적용한 레이저 레이더용 송수광 내접형 광학계 설계
고해석,옥창민,홍진석,이창재,박찬근,김현규,Koh, Hae Seog,Ok, Chang Min,Hong, Jin Sug,Lee, Chang Jae,Park, Chan Geun,Kim, Hyun Kyu 한국광학회 2013 한국광학회지 Vol.24 No.1
In this paper, an optical system was designed for 3D imaging laser radar with optical scanner. In order to make it easy to scan, the system was designed to inscribe the transmitting objective lens in the receiving lens. In transmitting optics, the beam expander was designed to have a zoom mechanism so that the transmitted beam size would be 4.8 m or 6.8 m at 1 km distance, when the laser source's numerical aperture value is between 0.13 and 0.22. The beam diameter at the target 1 km away was confirmed by design program. The receiving optics for the returning beam from the target was designed for the $16{\times}16$ array detector with $100{\mu}m$ pixel width. The spot diameter in every pixel was designed and verified to be less than $55{\mu}m$. The receiving optics' obscuration ratio by transmitting optics was 11%. 송광광학계의 광원으로 사용되는 광섬유 레이저의 개구수, NA가 0.13~0.22의 범위에 있으면, 이 NA에 관계없이 1 km 전방에서 빔직경이 4.8 m 또는 6.8 m이 되도록 줌렌즈형 광속확대기를 적용한 송광광학계를 설계하였으며, 표적에서의 foot prints를 통하여 빔직경을 확인하였다. $16{\times}16$($100{\mu}m{\times}100{\mu}m$) 픽셀 검출기를 사용하는 수광광학계를 설계하였으며, 검출면의 픽셀 위치에 따른 spot diameter는 모두 $55{\mu}m$ 이하가 됨을 확인하였다. 스캔을 고려하여 송광광학계를 수광부 대물렌즈에 내접하도록 구성하였으며, 이때 송광부에 의하여 가려진 부분은 11%가 되었다.
신완순,고해석,박병서,강응철,Shin, Wan-Soon,Koh, Hae-Seog,Park, Byung-Suh,Kang, Eung-Cheol 한국군사과학기술학회 2012 한국군사과학기술학회지 Vol.15 No.5
The purpose of this study is to develop the model to estimate the penetration rate of metal under a high power continuous wave laser irradiation. To estimate it, an empirical modeling is more practical when the penetration phenomena of metal by laser irradiation is too complex to be analyzed by the numerical simulation. When several methods published earlier were applied to our results, we found out that their methods were not appropriate as the model. Therefore, we suggested the new empirical method considering effective intensity as a key variable. As a result, we confirmed that the new method was effective to model the penetration rate of SUS304 metal and expected that it could be available to other metals.
라만매질 CH₄의 전후방 1.54 ㎛ 유도라만 산란광의 비대칭적 발생
최영수(Young Soo Choi),고해석(Hae Seog Koh),강응철(Eung Cheol Kang) 한국광학회 1999 한국광학회지 Vol.10 No.2
파장 1.06 ㎛ Nd:YAG 펌프레이저의 인가에너지와 라만매질 CH₄의 압력변화에 따른 전방과 후방 1.54 ㎛ 유도라만 산란광(stimulated Raman scattering)의 출력 특성을 동시에 측정하여 전후방 유도라만 산란광 발생을 위한 1.06 ㎛ 인가문턱에너지, 라만변환의 기울기 효율 및 라만이득계수(Raman gain coefficient)의 측정값과 이론값을 비교 분석하였다. 압력 1000 psi에서 후방 기울기 효율은 약 34%이고 전방은 약 18%를 보였다. 라만매질 CH₄의 압력이 증가할수록 전방과 후방 라만이득은 비선형적으로 증가할 뿐만 아니라, 후방 대 전방 라만이득비도 증가하였다. 압력 1200 psi 이상에서 후방 대 전방 라만이득비는 약 1.4배가 되었고, 압력 1400 psi에서 후방 라만이득계수는 0.32 ㎝/GW이고 전방에서는 0.23 ㎝/GW로 나타났다. 이와 같은 비대칭적 발생은 전방 라만증폭이 펌프광의 국부적 세기와 작용하는 반면 후방은 펌프광의 평균세기와 상호작용하기 때문이다. The 1.54 ㎛ forward and backward stimulated Raman scattering (SRS) have been studied in CH₄ gas pumped by 1.06 ㎛ Nd:YAG laser. The forward and backward SRS output energy in a single pass were measured at different CH₄pressures. Under steady state conditions, the pump input threshold energies and Raman gains in forward and backward directions were measured and calculated at various CH₄pressures for a tight focusing geometry. The forward and backward slope efficiency for Raman conversion were 18% and 34% respectively. The pump input threshold energy of the backward SRS was lower than that of the forward. In backward SRS, the experimental input laser threshold and Raman gain values were in good agreement with the calculated values at different pressures of CH₄. The ratio of the backward to the forward SRS gain was approximately 1.4 times above 1200 psi. We obtained that the backward Raman gain coefficient was 0.32 ㎝/GW, and the forward Raman gain coefficient 0.23 ㎝/GW at 1400 psi. Asymmetry of the forward and backward Raman gain is caused by the interaction between different pump intensities of each direction during the amplification of the Stokes. The backward Raman gain is proportional to the average pump intensity. However, the forward SRS output grows by depleting the local pump intensity.