共查询到20条相似文献,搜索用时 31 毫秒
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建立了光强分布为高斯型的抽运光端面单程抽运时薄片激光器的温度模型, 实验测量了不同抽运功率下薄片介质表面的 温度分布、温度随时间的变化特性以及介质表面的温度差. 采用Hartmann法测量了薄片介质的热焦距. 考虑热焦距随抽运功率的变化, 基于四能级系统薄片激光器的速率方程组, 建立了薄片激光器热效应对输出功率影响的物理模型, 薄片激光器输入-输出功率曲线与实际相符. 所得结果对薄片激光器的设计和优化具有一定的指导意义. 相似文献
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Thermal-lens measurement of a quasi steady-state repetitively flashlamp-pumped Cr, Tm, Ho:YAG laser 总被引:1,自引:0,他引:1
A simple technique using cavity stability conditions is demonstrated to measure the effective dynamic thermal lensing of a flashlamp-pumped Cr, Tm, Ho:YAG laser operated in a low repetition-rate regime of 4–7 Hz. By measuring the flashlamp energy where a stable resonator becomes unstable, the effective focal length of the laser rod can be calculated. When no mode restricting aperture is used in the cavity, the thermal lens behaviour displays a significant deviation from the commonly assumed thin lens approximation. 相似文献
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Metal thin film ablation with femtosecond pulsed laser 总被引:2,自引:0,他引:2
Micromachining thin metal films coated on glass are widely used to repair semiconductor masks and to fabricate optoelectrical and MEMS devices. The interaction of lasers and materials must be understood in order to achieve efficient micromachining. This work investigates the morphology of thin metal films after machining with femtosecond laser ablation using about 1 μm diameter laser beam. The effect of the film thickness on the results is analyzed by comparing experimental images with data obtained using a two-temperature heat transfer model. The experiment was conducted using a high numerical aperture objective lens and a temporal pulse width of 220 fs on 200- and 500-nm-thick chromium films. The resulting surface morphology after machining was due to the thermal incubation effect, low thermal diffusivity of the glass substrate, and thermodynamic flow of the metal induced by volumetric evaporation. A Fraunhofer diffraction pattern was found in the 500-nm-thick film, and a ripple parallel to the direction of the laser light was observed after a few multiple laser shots. These results are useful for applications requiring micro- or nano-sized machining. 相似文献
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大气热晕效应引起的激光焦移的计算与分析 总被引:1,自引:0,他引:1
采用薄透镜组合的半解析近似方法,研究了大气中的热晕效应对激光聚焦的影响.用该计算方法得出结论:大气热晕效应对高功率激光聚集光束传输的影响与其初始功率、发射口径、传输路径及大气吸收系数有关.在吸收系数随距离增加而减少的光程上(如上行传输),热晕将导致焦点向远离发射点方向移动,而在吸收系数随传输距离增加而增加的光程上(如下行传输),热晕将导致焦点向靠近发射点方向移动. 相似文献
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Summary A mathematical model of the far-field diffraction pattern of a laser beam with laser heating self-phase modulation through
an optically thin film is presented. We deal with the steady-state temperature field generated by the weak absorption of a
laser beam in an optically and thermally thin film bounded by two transparent plates, the cell walls, whose thermal exchange
to the surrounding ambient has been assumed to be linear in the temperature difference to the ambient. These hypotheses describe
the application of the steady-state ?thermal lens? spectroscopy to the detection of the optical or thermal properties of liquid
samples. We give a very simple expression for the diffracted intensity that appears suitable for fast computer calculations.
The good accuracy of the technique is shown by comparison with the results given by more intricate approaches.
To speed up publication, the authors of this paper have agreed to not receive the proofs for correction. 相似文献
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When an autostereoscopic three dimensional (3D) display based on a single lenticular lens keeps working for a long period, the thermal expansion of lenticular lens results in serious crosstalk and 3D image deterioration. To overcome this problem, a combined lenticular lens is proposed. The combined lenticular lens is composed of a single lenticular lens used in the traditional autostereoscopic 3D display, a transparent glue layer and a glass substrate. The design method of the combined lenticular lens and analysis of thermal expansion effect is given. A 42-inch autostereoscopic 3D display based on the combined lenticular lens is developed. The experiment results verify that the proposed combined lenticular lens effectively avoids the crosstalk and 3D image deterioration happened in the traditional autostereoscopic 3D display. 相似文献
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端侧面组合抽运DPL热透镜效应研究 总被引:1,自引:0,他引:1
通过数值计算发现:在端侧面组合抽运DPL中,晶体横截面上的温度分布接近于轴对称分布,并且端面抽运功率占有率越大,温度分布越接近于轴对称分布。将端侧面组合抽运DPL中的热效用等效薄透镜近似,给出了等效热透镜焦距的计算方法,分析了组合抽运引起的热透镜效应对基横模振荡光的光斑尺寸和衍射损耗的影响。在总抽运功率一定的情况下,端面抽运功率占有率的变化对热透镜焦距有一定的影响,占有率越大,热透镜焦距越长。提高端面抽运功率占有率,可在一定程度上减小热透镜效应对振荡光束尺寸和衍射损耗的影响。 相似文献
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本文分析了自准法测定薄凸透镜的焦距实验教学中的一个“奇怪”现象,导出把薄凸透镜的第二球面作为反射面时的成像公式,利用它可以很好地解释实验教学中的问题。并可以测定薄凸透镜的曲率半径和焦距。 相似文献
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Qinghong Zhou 《Optics Communications》2011,284(18):4207-4214
With the FEA and matrix methods, the thermal lenses induced by the thermooptic effect, thermally induced mechanical strain and end face bulging in a Ti:sapphire crystal are analyzed. The results show that there is an unignorable strain-induced lens in a high pump power region. With the thermal lens effect, an injection-locked cw Ti:sapphire laser is numerically simulated. We find that the poor mode matching between the lasing and pump beams due to thermal lens will cause the slope efficiency decreasing. The calculated results agree with the reported experimental data, and we also predict that the thermal lens is obviously active at a certain pump power level. 相似文献
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Correlated two-photon imaging with true thermal light 总被引:4,自引:0,他引:4
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A cryogenically cooled Ti:sapphire regenerative ring amplifier was developed as a laser for generating a laser-produced plasma light source. With a 10 kHz 180 W pump laser, the amplifier output is 40 W before compression and 26 W after compression. We believe it to be the current highest average-power output from a single stage Ti:sapphire amplifier. The effective focal length of the thermal lens is measured to be 2.2 m at 100 K for 180 W of pump power. With a 1 m focal length lens placed in the resonator, the effect of a thermal lens on the resonator mode is suppressed. High conversion efficiency is achieved for the whole pumping power range without any additional measures for thermal compensation. 相似文献